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Methodological considerations in the assessment of direct and indirect costs of back pain: A systematic scoping review

  • Dawit T. Zemedikun ,

    Roles Writing – original draft, Writing – review & editing

    Affiliation Health Economics Unit, Institute of Applied Health Research, University of Birmingham, Birmingham, England, United Kingdom

  • Jesse Kigozi,

    Roles Supervision, Writing – review & editing

    Affiliation Health Economics Unit, Institute of Applied Health Research, University of Birmingham, Birmingham, England, United Kingdom

  • Gwenllian Wynne-Jones,

    Roles Conceptualization, Supervision, Writing – review & editing

    Affiliation Primary Care Centre Versus Arthritis, Research Institute for Primary Care & Health Sciences, Keele University, Staffordshire, Keele, England, United Kingdom

  • Alessandra Guariglia,

    Roles Supervision, Writing – review & editing

    Affiliation Department of Economics, University of Birmingham, Birmingham, England, United Kingdom

  • Tracy Roberts

    Roles Conceptualization, Supervision, Writing – review & editing

    Affiliation Health Economics Unit, Institute of Applied Health Research, University of Birmingham, Birmingham, England, United Kingdom

Methodological considerations in the assessment of direct and indirect costs of back pain: A systematic scoping review

  • Dawit T. Zemedikun, 
  • Jesse Kigozi, 
  • Gwenllian Wynne-Jones, 
  • Alessandra Guariglia, 
  • Tracy Roberts



Back pain is a common and costly health problem worldwide. There is yet a lack of consistent methodologies to estimate the economic burden of back pain to society.


To systematically evaluate the methodologies used in the published cost of illness (COI) literature for estimating the direct and indirect costs attributed to back pain, and to present a summary of the estimated cost burden.


Six electronic databases were searched to identify COI studies of back pain published in English up to February 2021. A total of 1,588 abstracts were screened, and 55 full-text studies were subsequently reviewed. After applying the inclusion criteria, 45 studies pertaining to the direct and indirect costs of back pain were analysed.


The studies reported data on 15 industrialised countries. The national cost estimates of back pain in 2015 USD ranged from $259 million ($29.1 per capita) in Sweden to $71.6 billion ($868.4 per capita) in Germany. There was high heterogeneity among the studies in terms of the methodologies used for analysis and the resulting costs reported. Most of the studies assessed costs from a societal perspective (n = 29). The magnitude and accuracy of the reported costs were influenced by the case definition of back pain, the source of data used, the cost components included and the analysis method. Among the studies that provided both direct and indirect cost estimates (n = 15), indirect costs resulting from lost or reduced work productivity far outweighed the direct costs.


Back pain imposes substantial economic burden on society. This review demonstrated that existing published COI studies of back pain used heterogeneous approaches reflecting a lack of consensus on methodology. A standardised methodological approach is required to increase credibility of the findings of COI studies and improve comparison of estimates across studies.


Cost of illness (COI) studies aim to identify and measure the economic impact of an illness including the direct and indirect costs [1, 2]. These studies are descriptive, and they quantify the costs without comparing alternative uses of healthcare resources. COI studies can, however, serve as a basis for further economic evaluations and they are particularly useful for chronic diseases that impact heavily on health expenditures [3, 4].

Back pain is a common health problem and is the leading cause of years lived with disability in most countries and age groups [57]. Although back pain has low impact in terms of mortality, it imposes great medical and non-medical related costs on patients, employers, and health care providers [1, 8, 9]. As society is aging worldwide, these costs are likely to rise putting further pressure on health care services.

Despite the substantial costs reported in COI studies of back pain, there is little guidance in the literature to support the choice of methodologies in those studies. Dagenais et al. [1] conducted a systematic review of COI studies in LBP focussing on the magnitude of the economic burden rather than the methodologies. Their review from 2007 was restricted to one biomedical database (Medline) and examined only studies published in the previous 10 years. In the intervening years, a number of studies have emerged across many countries. There is a clear lack of consensus about the appropriate methodologies to use to estimate the economic impact of back pain. The objective of this review was to systematically gather and characterise the body of literature on the direct and indirect costs of back pain in order to evaluate the methodological approaches used by researchers in developing COI studies of back pain. We also present the resulting national estimates of direct and indirect costs of back pain from the reviewed studies.


We conducted a systematic scoping review guided by the framework introduced by Arksey and O’Malley [10], and following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) [11] guidelines for reporting.

Search strategy

Six electronic databases (MEDLINE, Embase, CINAHL Plus, Web of Science, EconLit, and Centre for Reviews and Dissemination (CRD)) were searched for studies published in English from inception to February 2021. We focussed the search on OECD countries where access and structure of the healthcare systems are more comparable amongst these high-income countries. The literature searches were conducted using a combination of keyword searching and medical subject headings (MeSH). The searches were made robust by making use of wildcards, phrase searching and truncation of the search terms as appropriate (S1 File). Only full text articles were considered ensuring that studies with sufficient methodological detail were assessed.

Inclusion and exclusion criteria.

Studies had to meet the following inclusion criteria:

  1. Conducted in the UK and other high income countries (OECD members [12]).
  2. Concerned with economic burden of back pain or low back pain.
  3. Cost provided as monetary estimate of direct or indirect costs.
  4. Studies investigating adult patients.
  5. Reports written in English.

The exclusion criteria used were as follows:

  1. Musculoskeletal conditions other than back pain.
  2. Economic evaluations of interventions.
  3. Review articles.
  4. Abstracts or conference proceedings.

Selection of studies for review.

Eligibility of the identified studies was assessed using a two-stage categorisation process (Table 1) that have been described in detail elsewhere [1315]. The categorisation process was designed to be as inclusive as possible so that no study fell outside of the predefined groups. One reviewer (DZ) screened studies initially by title and then categorised them into six groups (A-F). This was followed by full text reading of potentially relevant studies and further classified them into eight groups (1–8). A second reviewer (JK) retrieved and reviewed a random sample of 25% of the studies at each stage of the selection process to assess agreement. Any discrepancies were resolved by discussion until a consensus was reached by all five authors. We did not exclude papers on quality grounds as the purpose of the review was to identify the range of methods that have been used to estimate the cost of back pain and to identify the entire range that has been apportioned to back pain, in order to inform a planned primary study.

For each study, a range of data including study characteristics, methodology used, and the results reported were extracted using an electronic template. The information was tabulated, and the methodology and findings of individual studies were compared narratively. For consistency and standardisation across studies, all costs were converted to 2015 US dollars using country-specific gross domestic product inflator index and purchasing power parity (PPP) conversion [16].


The search identified a total of 8,009 potential citations. After removing duplicates and title screening of the citations, 1,588 studies reached the initial categorisation stage. Following the initial categorisation by title and abstract, 55 studies were included in the second stage of the review process. These articles were read in full and further classified to determine their suitability for inclusion resulting in a total of 45 studies coded A(1), A(2), B(1), and B(2) that met the criteria for the review (Fig 1).

The 45 studies included 17 studies (39%) from the United States [1733], five (11%) from Sweden [3438], four (9%) from The Netherlands [3942], and three (7%) each from the UK [9, 43, 44], Germany [4547], and Japan [4850] (Table 2). The studies were published from 1995 to 2020, and the data collection spanned from 1987 to 2017. The age of data at the time of publication in the reviewed studies ranged from one year [30] to 11 years [18, 28]. There was also high heterogeneity among the studies in terms of the methodologies used for analysis and the resulting cost estimates reported.

The main methodological characteristics of the included studies are summarised below. A general description of the introductory concepts and approaches used in COI studies is first given (Table 3).

Back pain diagnostic criteria

International Classification of Diseases codes (ICD-9 or ICD-10 codes) or a variant of these were typically used to define back pain by over half of the studies, while self-reported back pain assessment was reported in 15 studies [1820, 26, 28, 35, 39, 45, 47, 49, 5155]. The diagnostic criteria used was not explicitly specified in some of the studies [19, 30, 50, 56, 57]. However, studies with diagnostic codes were often used to produce national cost estimates compared to studies with self-reported or non-specific back pain definition types that mainly provided either average costs per patient or indirect cost estimates.

Source of data

A diverse range of data sources were used including surveys, national databases, compensation claims and cost diaries. Multiple sources of data were typically used in many of the studies, and the reported direct or indirect costs were the result of combining and summing an array of data sources. Large-scale surveys, and claims databases dominated the source of utilisation data with the latter being used mainly in insurer perspective studies. The use of electronic health records (EHRs) and registry data was limited [34, 37, 38, 41, 43]. In the US, the Medical Expenditure Panel Survey (MEPS) database was the single most common source of data for analysing COI for back pain [22, 24, 28, 29].

Perspective of the analysis

The societal perspective which is preferred since it is the most comprehensive perspective was adopted by the majority of the studies (n = 29) while only two studies followed a healthcare perspective [43, 51]. Taking the viewpoint of insurance-based health care, the insurer perspective was the second most popular [17, 20, 21, 23, 25, 27, 31, 32, 46, 50, 56] perspective. It was apparent that most of the insurer perspective studies (9 out of 12) were US studies [17, 20, 21, 23, 25, 27, 3133] conducted using claims databases. Cost analysis from industry or employer perspective is limited in its scope and was less common [18, 19].

Cost components

No significant methodological differences were observed between studies that assessed both direct, and indirect costs (n = 23) and those that reported on direct costs only [17, 2123, 25, 27, 29, 31, 43, 46, 48, 51, 56] or indirect costs only [18, 20, 26, 28, 30, 40, 44]. This review examined the cost components reported with the aim of identifying the most important cost drivers. For direct costs, studies reporting all three major components of inpatient, outpatient, and pharmaceutical costs were summarised for comparison (Fig 2). Outpatient cost was the most important cost driver in the majority of the studies, followed by inpatient cost.

Fig 2. Allocation of direct costs in COI studies of back pain.

Legend: The figure illustrates the allocation of direct costs in studies that reported on all three major costs components (inpatient, outpatient, and pharmaceutical costs) of direct costs.

For indirect costs, this review compared studies reporting at least two of the three major cost components of absenteeism, presenteeism and early retirement (Fig 3). Absenteeism which was assessed in all the studies compared was the most relevant cost driver in most studies. Although presenteeism was only assessed in five of the studies, it was found to be the most significant cost component in three of them representing 44%, 70% and 85% of the total indirect costs.

Fig 3. Allocation of indirect costs in COI studies of back pain.

Legend: The figure illustrates the allocation of indirect costs in studies that reported on at least two of the three major costs components (absenteeism, presenteeism, and early retirement costs) of indirect costs.

Estimating resource utilisation

The bottom-up approach was a commonly adopted method (n = 29) to calculate the direct costs of back pain compared to the top-down approach [9, 34, 37, 41, 42, 5759]. The top-down approach was preferred in studies where cost data were widely available from national health statistics. Cost estimations were more detailed in bottom-up studies since individual-level data were aggregated to get the population-level estimates. However, the application of an incremental cost method using a matched-control or econometric methods was limited [17, 2225, 43].

Indirect cost estimation

The human capital (HC) approach was typically applied [26, 28, 30, 3438, 41, 42, 45, 47, 49, 52, 53, 55, 58, 60] in studies that estimated the indirect costs of back pain. The use of both HC and friction cost (FC) approaches was limited [9, 40, 54, 59]. In studies that applied both methods, the HC approach resulted in significantly higher estimates of the indirect costs of back pain. Hutubessy et al. [40] reported the indirect costs of back pain in The Netherlands in 1991 to be $1.5 billion using the FC method; but this increased by three-fold to $4.6 billion under the HC approach.

The annual national cost estimates of back pain from 26 studies that reported national estimates are summarised in Table 4. The total cost estimates in 2015 USD ranged from $259 million ($29.1 per capita) in Sweden to $71.6 billion ($868.4 per capita) in Germany. Direct comparison of costs between the studies is not feasible due to significant differences in the methodologies adopted. In studies that provided both direct and indirect cost estimates (n = 15), indirect costs generally far outweighed the direct costs (S2 File). Measures of precision or dispersion such as confidence intervals or standard deviations around cost estimates were rarely reported in the included studies, and those that reported were largely limited to studies that applied econometric methods for cost estimation [17, 23, 24, 43]. In addition, the measures given were generally for the sample estimates (average resource use or cost) rather than for the extrapolated national cost estimates. This review also uncovered that sensitivity analysis is often not conducted in COI studies with only few studies [9, 24, 39, 43, 47, 54, 58, 59] performing any sensitivity analysis. Moreover, the use of an alternative cost estimation method was considered only in a minority of the studies [9, 24, 40, 54, 59] but resulted in considerably different estimates, particularly for indirect costs. Irrespective of the analysis method used, the reported results reveal the significant economic burden of back pain on healthcare systems and society as a whole.

Table 4. National estimates of direct, indirect, and total costs of back pain.


This review examined 45 COI studies with the aim of assessing the methodologies used to estimate direct and indirect costs associated with back pain. The findings of the review indicated that there is little consensus in the methodologies used to derive cost estimates for back pain, and the reported costs were substantial and wide-ranging.

Summary of findings

Findings from the included studies confirm that back pain is a costly problem worldwide. The national cost estimates ranged from $259 million to $71.6 billion. It was clear from the studies reviewed that indirect costs were the main cost drivers for back pain and consequently, major cost savings could be obtained from interventions that bring about early return to work and reduce productivity losses. Outpatient costs were the main cost drivers of direct costs, while absenteeism represented the largest share of indirect costs. However, in the case of indirect costs, our review indicated that presenteeism is often underexplored but represents a significant proportion of the indirect costs of an illness. The significance of presenteeism for the value of lost production were also highlighted in previous literature [54, 61, 62]. A sound methodological framework for the assessment of presenteeism poses a challenge, but the potential impact of presenteeism on costs needs to be included in order to improve the reliability of results [61, 62].

Several factors were likely to have influenced the magnitude and accuracy of the estimates reported. Comparing and generalising these quantitative results is problematic because significantly different approaches had been adopted to estimate the economic burden of back pain. The validity of each method would be related to the available data and the proposed use of the findings. Hence, this review did not find any particular features that should be absolutely avoided to generate valid data. Almost all studies that assessed direct costs reported costs relating to inpatient, outpatient, and pharmaceutical costs; however, few studies included costs relating to emergency department, occupational therapy, or allied health care. Similarly, only few studies included all three major components of indirect costs potentially indicating lack of data source or standardised instruments for the assessment of some indirect cost components. Hence, a wide range of estimates were found across the included studies both nationally and internationally.

Key methodological challenges

The discrepancies in reported costs and methodologies did not appear to be attributed to the cost perspective taken since most studies adopted the societal perspective. The main sources of variations in the methodologies used in COI studies of back pain were the way in which back pain was defined, the sources of data used, the cost components included, and the approaches used to estimate both direct and indirect costs (e.g. Top-down vs. bottom-up or human capital vs. friction cost methods). There were also considerable discrepancies between the year of data used and the year of publication which should be carefully considered in order to avoid drawing conclusions from outdated data. Quantitative estimates reported should therefore be interpreted with caution taking into account any changes that may have taken place in the time period between pricing and publication.

Diagnosis of back pain should ideally be on clearly defined criteria so that studies might be comparable and replicated as necessary. Consensus on criteria and assessment of the reported cases may be a practical solution for addressing the discrepancies in case definitions [63]. The main data sources reported for direct cost estimates were large surveys and insurance claims databases. Self-reported measures for healthcare resource utilisation are known to have limitations with validity of the data due to recall bias [64, 65]. Since many episodes of back pain are recurrent and short lived [66], resource utilisation may crucially be under-reported in survey-based studies. In studies using insurance claims data, the claims might be subject to co-pays, and deductibles or the insurance coverage may vary from plan to plan or from employer to employer. Moreover, since cost estimations are conducted in relation to insured individuals, generalisation of the findings to the wider population may not be appropriate.

The number and type of cost components reported in the studies were highly heterogeneous for both the direct and indirect cost categories. Some studies focussed only on major cost components of consultations, prescriptions, and hospitalisations, whereas others also considered services such as diagnostic imaging, physiotherapy, and accident and emergency. This meant that significant discrepancies existed in reported costs, and studies with partial estimates of healthcare costs could not be compared with those reporting full COI estimates.

The way in which healthcare resource utilisation is valued could also impact on the reported costs. Most studies used a direct method of summing up back pain related costs which underestimated the true cost of back pain compared to an incremental cost approach. The incremental approach was more comprehensive and accounted for costs that would otherwise have been missed such as costs due to comorbidities resulting from back pain. Valuation of indirect costs using the human capital and friction cost approaches also resulted in widely different estimates with the HC method consistently producing significantly higher costs than the FC method. However, unlike the direct cost estimation methods, the justification for the choice of one method over the other is not clear and there is ongoing debate as to the best method [6769]. A review and assessment of the evidence suggests that a pragmatic approach is to use both the HC and FC approaches as sensitivity analyses [70].

Strengths, limitations, and comparison with other studies

This is the first review aimed at assessing the methodologies used in COI studies of back pain. The previous review [1], which focussed on synthesising results rather than methodologies, was from 2008 and the findings were slightly limited by only including studies published in the previous 10 years. A major strength of this review was that large number of studies were included that varied greatly by country and methodology, and the search was conducted with no restriction on publication date. Methodological differences that may not always be apparent but resulting in significant influence on COI estimates of back pain were revealed by this review. A potential limitation was that this review only considered studies conducted in developed countries and published in English. Nevertheless, the findings of this review can be considered robust given that such a large number of studies were examined.

It was noteworthy that several studies did not explicitly describe their methodologies posing challenges to assess them. This lack of clarity is also confirmed by other systematic reviews [1, 7173], and appears to be a common feature of COI studies. There was also a lack of consensus and guideline on the use of methodologies which may make the analyses prone to underestimation or overestimation of the true costs of the illness. This finding is consistent with that of other systematic reviews of COI analyses, and was not restricted to back pain [7477]. Another limitation was that the studies did not explicitly report on costs of complications such as revision surgery for infection which are a major source of treatment costs post-surgery. No such distinction was made between costs due to complications and other costs. Furthermore, sensitivity analysis does not appear to be a standard practice in current COI studies with only a minority of studies conforming to the norm. Sensitivity analysis is also rarely done in COI studies of other conditions [72, 74].

Key implications and recommendations

The lack of standardised and validated instrument and research methodology in COI studies meant that researchers must be careful with their terminology, data source, and methodology used for estimation. Certain types of approaches might be more appropriate than others which has implications for replicating and validating a specific study. The methodological considerations highlighted in this review offer practical guidance to researchers, decision makers, and funders in designing future COI studies. The trade-offs in the various methodological options available for performing the calculations and their effects on the resulting cost estimates should not be underestimated. Stakeholders should consider what degree of accuracy is required in COI analysis to ascertain the appropriate methods that will meet decision makers’ needs.

Based on the findings of this review, some important recommendations for good practice can be drawn which may help produce more reliable estimates for the costs of back pain with implications for COI studies in general:

  • As back pain imposes an enormous economic burden, costs must be estimated more accurately and inclusively, and a bottom-up approach using an incremental cost method is recommended as base case analysis.
  • Identification of cases should be based on a broad consensus on case definition of back pain, and the use of diagnostic codes is preferred.
  • Resource utilisation may be better estimated by following up a large sample of patients from electronic health records, and valuation of unit costs should be carefully assessed.
  • Patient characteristics, such as comorbidities, should be clearly reported. Where appropriate, separate cost estimates need to be reported for subgroups of patients.
  • Researcher should test the sensitivity of the analysis, give detailed descriptions, and discuss limitations of the methodological choices.
  • Finally, development of guideline and standardisation of the methodologies used for COI studies may not only enhance the reliability and interpretation of the estimates, but it also enables comparability of the results across studies.


COI studies may provide important information and serve as a basis for further economic evaluations and allocation of resources. In the absence of widely accepted standards and consensus on methodology, conducting a COI study capable of identifying and measuring the true cost of an illness remains a challenge. Methodological variations and the discrepancies that arise within them have direct impact on the comparability and credibility of COI studies. This review has reported a widespread heterogeneity in the methodologies used, and the substantial direct or indirect cost estimates produced for back pain. By informing the relative importance of this health problem, the information obtained here has important implications on the allocation of scarce resources and other health policy decision making.

This review also highlighted some factors that might have substantial impact on the reported cost estimates. Recommendations about good practice for COI studies of back pain have been suggested based on the findings of this review. These recommendations may help obtain reliable estimates of the true cost of the illness, improve the quality and reporting of the analysis, and provide validity to COI studies.

Supporting information

S1 File. Example of search strategy constructed with breakdown of hits obtained.


S2 File. Comparison of the direct and indirect costs of back pain and the cost components included.



The authors thank Dr Majid Artus PhD for his expertise on the clinical area, and the comments and feedback received on the draft manuscripts.


  1. 1. Dagenais S, Caro J, Haldeman S. A systematic review of low back pain cost of illness studies in the United States and internationally. Spine J. 2008;8(1):8–20. pmid:18164449
  2. 2. Jo C. Cost-of-illness studies: concepts, scopes, and methods. Clinical and molecular hepatology. 2014;20(4):327–37. pmid:25548737
  3. 3. Rice DP. Cost of illness studies: what is good about them? Inj Prev. 2000;6(3):177–9. pmid:11003181
  4. 4. Clabaugh G, Ward MM. Cost-of-illness studies in the United States: a systematic review of methodologies used for direct cost. Value Health. 2008;11(1):13–21. pmid:18237356
  5. 5. Murray CJ, Vos T, Lozano R, Naghavi M, Flaxman AD, Michaud C, et al. Disability-adjusted life years (DALYs) for 291 diseases and injuries in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet. ET AL. (GBD 2010 Collaborators) 2012;380(9859):2197–223. pmid:23245608
  6. 6. Vos T, Allen C, Arora M, Barber MR, Bhutta AZ, Brown A, et al. Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990–2015: a systematic analysis for the Global Burden of Disease Study 2015. Lancet. ET AL. (GBD 2015 Disease and Injury Incidence and Prevalence Collaborators) 2016;388(10053):1545–602. pmid:27733282
  7. 7. Hurwitz EL, Randhawa K, Yu H, Cote P, Haldeman S. The Global Spine Care Initiative: a summary of the global burden of low back and neck pain studies. Eur Spine J. 2018;27(Suppl 6):796–801. pmid:29480409
  8. 8. Hoy DG, Smith E, Cross M, Sanchez-Riera L, Buchbinder R, Blyth FM, et al. The global burden of musculoskeletal conditions for 2010: an overview of methods. Ann Rheum Dis. 2014b;73(6):982–9.
  9. 9. Maniadakis N, Gray A. The economic burden of back pain in the UK. Pain. 2000;84(1):95–103. pmid:10601677
  10. 10. Arksey H, O’Malley L. Scoping Studies: Towards a Methodological Framework. Int J Social Research Methodology. 2005;8(1):19–32.
  11. 11. Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gotzsche PC, Ioannidis JP, et al. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration. PLoS Med. 2009;6(7):e1000100. pmid:19621070
  12. 12. World-Bank. Doing Business 2019 Regional Profile: OECD High Income. 2019.
  13. 13. Jackson LJ, Auguste P, Low N, Roberts TE. Valuing the health states associated with Chlamydia trachomatis infections and their sequelae: a systematic review of economic evaluations and primary studies. Value Health. 2014;17(1):116–30. pmid:24438725
  14. 14. Jackson LJ, Roberts TE. Measuring Health and Quality of Life for Women Undergoing Testing and Screening for Chlamydia: A Systematic Review. Sex Transm Dis. 2016;43(3):152–64. pmid:26859802
  15. 15. Roberts T, Henderson J, Mugford M, Bricker L, Neilson J, Garcia J. Antenatal ultrasound screening for fetal abnormalities: a systematic review of studies of cost and cost effectiveness. Bjog-Int J Obstet Gy. 2002;109(1):44–56.
  16. 16. Shemilt I, Thomas J, Morciano M. A web-based tool for adjusting costs to a specific target currency and price year. Evidence & Policy. 2010;6:51–9.
  17. 17. Gore M, Sadosky A, Stacey BR, Tai KS, Leslie D. The burden of chronic low back pain: clinical comorbidities, treatment patterns, and health care costs in usual care settings. Spine. 2012;37(11):E668–77. pmid:22146287
  18. 18. Guo H, Tanaka S, Halperin WE, Cameron LL. Back pain prevalence in US industry and estimates of lost workdays. American Journal of Public Health. 1999;89(7):1029–35. pmid:10394311
  19. 19. Gustafson DH, Helstad CP, Hung CF, Nelson G, Batalden P. The total costs of illness: A metric for health care reform. Hospital and Health Services Administration. 1995;40(1):154–71. pmid:10172238
  20. 20. Hashemi L, Webster BS, Clancy EA. Trends in disability duration and cost of workers’ compensation low back pain claims (1988–1996). J Occup Environ Med. 1998;40(12):1110–9. pmid:9871888
  21. 21. Lind BK, Lafferty WE, Tyree PT, Sherman KJ, Deyo RA, Cherkin DC. The role of alternative medical providers for the outpatient treatment of insured patients with back pain. Spine. 2005;30(12):1454–9. pmid:15959379
  22. 22. Luo X, Pietrobon R, Sun SX, Liu GG, Hey L. Estimates and patterns of direct health care expenditures among individuals with back pain in the United States. Spine. 2004;29(1):79–86. pmid:14699281
  23. 23. Mapel DW, Shainline M, Paez K, Gunter M. Hospital, pharmacy, and outpatient costs for osteoarthritis and chronic back pain. J Rheumatol. 2004;31(3):573–83. pmid:14994407
  24. 24. Martin BI, Deyo RA, Mirza SK, Turner JA, Comstock BA, Hollingworth W, et al. Expenditures and health status among adults with back and neck problems. JAMA. 2008;299(6):656–64. pmid:18270354
  25. 25. Mehra M, Hill K, Nicholl D, Schadrack J. The burden of chronic low back pain with and without a neuropathic component: a healthcare resource use and cost analysis. Journal of Medical Economics. 2012;15(2):245–52. pmid:22136441
  26. 26. Ricci JA, Stewart WF, Chee E, Leotta C, Foley K, Hochberg MC. Back pain exacerbations and lost productive time costs in United States workers. Spine. 2006;31(26):3052–60. pmid:17173003
  27. 27. Ritzwoller DP, Crounse L, Shetterly S, Rublee D. The association of comorbidities, utilization and costs for patients identified with low back pain. BMC Musculoskelet Disord. 2006;7:72. pmid:16982001
  28. 28. Rizzo JA, Abbott TA 3rd, Berger ML. The labor productivity effects of chronic backache in the United States. Med Care. 1998;36(10):1471–88. pmid:9794341
  29. 29. Smith M, Davis MA, Stano M, Whedon JM. Aging baby boomers and the rising cost of chronic back pain: secular trend analysis of longitudinal Medical Expenditures Panel Survey data for years 2000 to 2007. J Manipulative Physiol Ther. 2013;36(1):2–11. pmid:23380209
  30. 30. Stewart WF, Ricci JA, Chee E, Morganstein D, Lipton R, Stewart WF, et al. Lost productive time and cost due to common pain conditions in the US workforce. JAMA: Journal of the American Medical Association. 2003;290(18):2443–54. pmid:14612481
  31. 31. Vogt MT, Kwoh CK, Cope DK, Osial TA, Culyba M, Starz TW. Analgesic usage for low back pain: impact on health care costs and service use. Spine. 2005;30(9):1075–81. pmid:15864162
  32. 32. Williams DA, Feuerstein M, Durbin D, Pezzullo J. Health care and indemnity costs across the natural history of disability in occupational low back pain. Spine. 1998;23(21):2329–36. pmid:9820914
  33. 33. Kim LH, Vail D, Azad TD, Bentley JP, Zhang Y, Ho AL, et al. Expenditures and Health Care Utilization Among Adults With Newly Diagnosed Low Back and Lower Extremity Pain. JAMA Netw Open. 2019;2(5):e193676. pmid:31074820
  34. 34. Ekman M, Johnell O, Lidgren L. The economic cost of low back pain in Sweden in 2001. Acta Orthop. 2005 (a);76(2):275–84. pmid:16097556
  35. 35. Ekman M, Jonhagen S, Hunsche E, Jonsson L. Burden of illness of chronic low back pain in Sweden: a cross-sectional, retrospective study in primary care setting. Spine. 2005 (b);30(15):1777–85. pmid:16094281
  36. 36. Hansson EK, Hansson TH. The costs for persons sick-listed more than one month because of low back or neck problems. A two-year prospective study of Swedish patients. Eur Spine J. 2005;14(4):337–45. pmid:15150703
  37. 37. Jonsson D, Husberg M. Socioeconomic costs of rheumatic diseases—Implications for technology assessment. International Journal of Technology Assessment in Health Care. 2000;16(4):1193–200. pmid:11155838
  38. 38. Olafsson G, Jonsson E, Fritzell P, Hagg O, Borgstrom F. Cost of low back pain: results from a national register study in Sweden. Eur Spine J. 2018;27(11):2875–81. pmid:30155730
  39. 39. Boonen A, van den Heuvel R, van Tubergen A, Goossens M, Severens JL, van der Heijde D, et al. Large differences in cost of illness and wellbeing between patients with fibromyalgia, chronic low back pain, or ankylosing spondylitis. Ann Rheum Dis. 2005;64(3):396–402. pmid:15271773
  40. 40. Hutubessy RCW, Van Tulder MW, Vondeling H, Bouter LM. Indirect costs of back pain in the Netherlands: A comparison of the human capital method with the friction cost method. Pain. 1999;80(1–2):201–7. pmid:10204732
  41. 41. Lambeek LC, Van Tulder MW, Swinkels ICS, Koppes LLJ, Anema JR, Van Mechelen W. The trend in total cost of back pain in the netherlands in the period 2002 to 2007. Spine. 2011;36(13):1050–8. pmid:21150697
  42. 42. van Tulder MW, Koes BW, Bouter LM. A cost-of-illness study of back pain in The Netherlands. Pain. 1995;62(2):233–40. pmid:8545149
  43. 43. Hong J, Reed C, Novick D, Happich M. Costs associated with treatment of chronic low back pain: an analysis of the UK General Practice Research Database. Spine. 2013;38(1):75–82. pmid:23038621
  44. 44. Watson PJ, Main CJ, Waddell G, Gales TF, Purcell-Jones G. Medically certified work loss, recurrence and costs of wage compensation for back pain: a follow-up study of the working population of Jersey. Br J Rheumatol. 1998;37(1):82–6. pmid:9487255
  45. 45. Becker A, Held H, Redaelli M, Strauch K, Chenot JF, Leonhardt C, et al. Low back pain in primary care: costs of care and prediction of future health care utilization. Spine. 2010;35(18):1714–20. pmid:21374895
  46. 46. Müller-Schwefe G, Freytag A, Höer A, Schiffhorst G, Becker A, Casser HR, et al. Healthcare utilization of back pain patients: results of a claims data analysis. Journal of Medical Economics. 2011;14(6):816–23. pmid:21992218
  47. 47. Wenig CM, Schmidt CO, Kohlmann T, Schweikert B. Costs of back pain in Germany. Eur J Pain. 2009;13(3):280–6. pmid:18524652
  48. 48. Itoh H, Kitamura F, Yokoyama K. Estimates of annual medical costs of work-related low back pain in Japan. Ind Health. 2013;51(5):524–9. pmid:23955653
  49. 49. Montgomery W, Sato M, Nagasaka Y, Vietri J. The economic and humanistic costs of chronic lower back pain in Japan. Clinicoecon Outcomes Res. 2017;9:361–71. pmid:28694702
  50. 50. Shinohara S, Okada M, Keira T, Ohwada M, Niitsuya M, Aizawa Y. Prognosis of accidental low back pain at work. Tohoku J Exp Med. 1998;186(4):291–302. pmid:10328161
  51. 51. Depont F, Hunsche E, Abouelfath A, Diatta T, Addra I, Grelaud A, et al. Medical and non-medical direct costs of chronic low back pain in patients consulting primary care physicians in France. Fundam Clin Pharmacol. 2010;24(1):101–8. pmid:19678853
  52. 52. Hemmilä HM. Quality of life and cost of care of back pain patients in Finnish general practice. Spine (03622436). 2002;27(6):647–53. pmid:11884913
  53. 53. Icatasiotlu A, Yumusakhuylu Y, Ketenci A, Toraman NF, Karatas GK, Kuru O, et al. Burden of chronic low back pain on turkish population, Kronik Bel Atrisinin Turk Toplumuna Maliyeti. [Turkish, English]. Turkiye Fiziksel Tip ve Rehabilitasyon Dergisi. 2013;59:287.
  54. 54. Wieser S. Cost of Low Back Pain in Switzerland in 2005. European Journal of Health Economics. 2011;12(5):455–67. pmid:20526649
  55. 55. Alonso-Garcia M, Sarria-Santamera A. The Economic and Social Burden of Low Back Pain in Spain: A National Assessment of the Economic and Social Impact of Low Back Pain in Spain. Spine (Phila Pa 1976). 2020;45(16):E1026–E32. pmid:32706566
  56. 56. Kim HS, Choi JW, Chang SH, Lee KS, Oh JY. Treatment duration and cost of work-related low back pain in Korea. J Korean Med Sci. 2005;20(1):127–31. pmid:15716617
  57. 57. van Zundert J, van Kleef M. Low back pain: From algorithm to cost-effectiveness? Pain Practice. 2005;5(3):179–87. pmid:17147580
  58. 58. Coyte PC, Asche CV, Croxford R, Chan B. The economic cost of musculoskeletal disorders in Canada. Arthritis Care Res. 1998;11(5):315–25. pmid:9830876
  59. 59. Walker BF, Muller R, Grant WD. Low back pain in Australian adults: the economic burden. Asia Pac J Public Health. 2003;15(2):79–87. pmid:15038680
  60. 60. Yumusakhuylu YB, H S., Aras H, Haliloglu S, Selimoglu E, Icagasioglu A. The Economic Cost of Chronic Low Back Pain. Bozok Med J. 2018;8(1):66–74.
  61. 61. Kigozi J, Jowett S, Lewis M, Barton P, Coast J. The Estimation and Inclusion of Presenteeism Costs in Applied Economic Evaluation: A Systematic Review. Value Health. 2017;20(3):496–506. pmid:28292496
  62. 62. Sogaard R, Sorensen J, Linde L, Hetland ML. The significance of presenteeism for the value of lost production: the case of rheumatoid arthritis. Clinicoecon Outcomes Res. 2010;2:105–12. pmid:21935319
  63. 63. Coggon D, Martyn C, Palmer KT, Evanoff B. Assessing case definitions in the absence of a diagnostic gold standard. Int J Epidemiol. 2005;34(4):949–52. pmid:16076861
  64. 64. Franklin M, Thorn J. Self-reported and routinely collected electronic healthcare resource-use data for trial-based economic evaluations: the current state of play in England and considerations for the future. BMC Med Res Methodol. 2019;19(1):8. pmid:30626337
  65. 65. Leggett LE, Khadaroo RG, Holroyd-Leduc J, Lorenzetti DL, Hanson H, Wagg A, et al. Measuring Resource Utilization: A Systematic Review of Validated Self-Reported Questionnaires. Medicine (Baltimore). 2016;95(10):e2759. pmid:26962773
  66. 66. Hoy D, Brooks P, Blyth F, Buchbinder R. The Epidemiology of low back pain. Best Pract Res Clin Rheumatol. 2010a;24(6):769–81.
  67. 67. Brouwer WB, Koopmanschap MA, Rutten FF. Productivity costs measurement through quality of life? a response to the recommendation of the Washington Panel. Health Econ. 1997;6(3):253–9. pmid:9226143
  68. 68. Koopmanschap MA, Rutten FF, van Inveld BM, van Roijen L. The friction cost method for measuring indirect costs of disease. J Health Econ. 1995;14(2):171–89. pmid:10154656
  69. 69. van den Hout WB. The value of productivity: human-capital versus friction-cost method. Ann Rheum Dis. 2010;69 Suppl 1:i89–91. pmid:19995754
  70. 70. Hanly P, Pearce A, Sharp L. The cost of premature cancer-related mortality: a review and assessment of the evidence. Expert Rev Pharmacoecon Outcomes Res. 2014;14:355–77. pmid:24746223
  71. 71. Bovolenta TM, de Azevedo Silva SMC, Arb Saba R, Borges V, Ferraz HB, Felicio AC. Systematic Review and Critical Analysis of Cost Studies Associated with Parkinson’s Disease. Parkinson’s Disease. 2017;2017:1–11. pmid:28357150
  72. 72. Molinier L, Bauvin E, Combescure C, Castelli C, Rebillard X, Soulie M, et al. Methodological considerations in cost of prostate cancer studies: a systematic review. Value Health. 2008;11(5):878–85. pmid:18494749
  73. 73. Pagano E, Brunetti M, Tediosi F, Garattini L. Costs of diabetes. A methodological analysis of the literature. Pharmacoeconomics. 1999;15(6):583–95. pmid:10538331
  74. 74. Costa N, Derumeaux H, Rapp T, Garnault V, Ferlicoq L, Gillette S, et al. Methodological considerations in cost of illness studies on Alzheimer disease. Health Econ Rev. 2012;2(1):18. pmid:22963680
  75. 75. Luppa M, Heinrich S, Angermeyer MC, Konig HH, Riedel-Heller SG. Cost-of-illness studies of depression: a systematic review. J Affect Disord. 2007;98(1–2):29–43. pmid:16952399
  76. 76. Verhaeghe N, Lievens D, Annemans L, Vander Laenen F, Putman K. Methodological Considerations in Social Cost Studies of Addictive Substances: A Systematic Literature Review. Front Public Health. 2016;4:295. pmid:28149834
  77. 77. Cooper NJ. Economic burden of rheumatoid arthritis: a systematic review. Rheumatology (Oxford). 2000;39(1):28–33. pmid:10662870