The authors have declared that no competing interests exist.
Conceived and designed the experiments: TF KDS MO SK EKN JU. Performed the experiments: TF KDS MO DNN LGA YN FZ JU. Analyzed the data: TF. Contributed reagents/materials/analysis tools: TF KDS MO DNN LGA YN FZ SK EKN JU. Wrote the paper: TF JU.
Burden of disease estimates are widely used for priority setting in public health and disability-adjusted life years are a powerful “currency” nowadays. However, disability weights, which capture the disability incurred by a typical patient of a certain condition, are fundamental to such burden calculation and their determination remains a widely debated issue.
A cross-sectional epidemiological survey was conducted in the recently established Taabo health demographic surveillance system (HDSS) in south-central Côte d'Ivoire, to provide new, population-based evidence on the disability caused by schistosomiasis and soil-transmitted helminthiasis. Parasitological results from stool, urine, and blood examinations were juxtaposed to quality of life (QoL) questionnaire results from 187 adults. A multivariable linear regression model with stepwise backward elimination was used to identify significant associations, considering also sociodemographic characteristics obtained from the Taabo HDSS database.
Prevalences for hookworm,
We found consistent and significant results on the negative effects of schistosomiasis and soil-transmitted helminthiasis on adults' self-rated QoL, also when taking sociodemographic characteristics into account. Our results warrant further investigation on the disability incurred by helmintic infections and the usefulness of generic QoL questionnaires in this endeavor.
In public health, "burden" estimates should capture the human suffering caused by certain health states, and the estimates are often used for priority setting. However, such "burden" estimates need to assess not only the number of affected people by certain conditions, but also the disability incurred by the average patient, and the determination of the degree of disability remains a widely debated issue. In order to provide new, population-based evidence on the disability caused by infections with parasitic worms, we administered a quality of life (QoL) questionnaire to 187 adults in rural Côte d'Ivoire and concurrently examined them for parasitic worm infections. We also considered sociodemographic characteristics in our analysis. In comparison with their non-infected counterparts, infected people reported a 13–16 points lower QoL on a scale from 0 (worst QoL) to 100 points (best QoL). At the same time, a one unit increase in a calculated wealth index revealed a 1-point increase in the participants' QoL. The results are consistent and warrant further investigation on the disability induced by parasitic worm infections and the usefulness of QoL questionnaires in this endeavor.
Efforts are underway for a comprehensive revision of the global burden due to major diseases, injuries, and risk factors
An undeniable merit of the global burden of disease concept is the renewed interest in descriptive epidemiology and population health measurement. Not surprisingly though, the concept also stimulated considerable controversies. Amongst other issues, criticism about the disability weights, which should measure the disability caused by a certain condition on a continuous scale from 0 (perfect health) to 1 (death), was raised as the original disability weights were solely based on expert opinion
In order to provide new, setting-specific, population-based evidence on the disability caused by schistosomiasis and soil-transmitted helminth infections, we conducted a cross-sectional survey among adults in the Taabo health demographic surveillance system (HDSS), in south-central Côte d'Ivoire. Generic quality of life (QoL) questionnaires and standardized, quality-controlled parasitological methods were applied and the results juxtaposed, taking into consideration readily available sociodemographic data from the Taabo HDSS database as potential confounders. To our knowledge, only few studies employed generic QoL questionnaires to assess disability attributable to helminth infections
The study protocol was approved by the institutional research commissions of the Swiss Tropical and Public Health Institute (Swiss TPH; Basel, Switzerland) and the Centre Suisse de Recherches Scientifiques en Côte d'Ivoire (CSRS; Abidjan, Côte d'Ivoire). Ethical clearance was provided by the ethics committee of Basel (EKBB; reference no. 316/08) and the Comité National d'Ethique et de la Recherche (CNER) in Côte d'Ivoire (reference no. 1086 MSHP/CNER).
The Taabo HDSS was set-up in mid-2008, located in the Taabo area in the south-central part of Côte d'Ivoire. While establishing the Taabo HDSS, district and village authorities and the general public were informed about its purpose, operational procedures, potential risks, and benefits. The present study was carried out in June 2010, readily embedded in the second cross-sectional epidemiological survey pursued once every year. Written informed consent was obtained from all participants. It was emphasized that participation was voluntary, and hence people could withdraw anytime without further obligation. All results were coded and kept confidential. At the end of the study, all people living in the Taabo HDSS were invited for deworming with albendazole (400 mg single oral dose) and ivermectin (∼200 µg/kg using a dose pole) irrespective of participants' infection status
The Taabo HDSS covers most of the rural Sous-Préfecture Taabo. Its main office is located in Taabo Cité, 160 km northwest of Abidjan. The region's tropical climate follows a seasonal pattern with a long dry season between November and April and two rainy seasons, a long one between April and July and a shorter one in September and October
The study was carried out in June 2010, readily embedded in the second annual cross-sectional epidemiological survey of the Taabo HDSS.
Vital statistics (i.e., pregnancy, birth, death, in-migration, and out-migration) and the health of some 38,500 individuals registered in the Taabo HDSS are monitored longitudinally. People are mainly engaged in subsistence farming of manioc, yams, and banana, while cacao and coffee are farmed as cash crops
For the present study, sociodemographic data on individual and household level were obtained from the Taabo HDSS database. Individual data included sex, age, relationship with the head of household, education, and main occupation. Household-level data contained information on the households' location, the number of household members, housing construction material, availability of certain facilities, and the possession of equipment.
All collaborators, including local health personnel, were trained and informed about the purpose, procedures, potential risks, and benefits of the cross-sectional survey and the deworming. Subsequently, key informants, field enumerators, and supervisors of the Taabo HDSS and the local health personnel informed all heads of households to visit, together with their families, a predefined, nearby survey location on a specified date and time to receive anthelmintic treatment. In addition, approximately 7% of all households in the Taabo HDSS were selected by stratified random sampling. These households were visited the day before the treatment and two plastic containers were distributed to all household members for collection of a lemon-sized fresh morning stool and a urine sample the next day.
On the day of treatment, people not selected for in-depth clinical and parasitological examinations received albendazole and ivermectin and they could continue with their daily chores (
The study was carried out in June 2010, readily embedded in the second annual cross-sectional epidemiological survey of the Taabo health demographic surveillance system (HDSS). In the frame of this second annual cross-sectional epidemiological survey, the whole population of the Taabo HDSS was offered anthelmintic treatment with albendazole and ivermectin. At the same time, people selected for an in-depth clinical and parasitological examination were invited to visit a series of different posts, including a quality of life (QoL) questionnaire for heads of households and a second adult household member of the opposing sex.
Blood, stool, and urine samples were transferred to the laboratory of the hospital in Taabo Cité and worked up the same day using standardized, quality-controlled techniques as described elsewhere
We used previously employed questionnaires in Côte d'Ivoire
The initial version of the questionnaire after translation into French was discussed with the field enumerators and supervisors of the Taabo HDSS. These field enumerators and supervisors are locals, who live in the different communities of the Taabo HDSS, are able to read, write, and speak French as well as the local languages Baoulé, Dioula, or Senufo. The questionnaire was further adapted based on their comments, then pre-tested in a nearby village and again refined in order to obtain the finally applied version (
Data were double-entered and cross-checked in EpiInfo version 3.5.1 (Centers for Disease Control and Prevention; Atlanta, United States of America) and analyzed in STATA version 10.1 (STATA Corp.; College Station, United States of America). For convenience, the myriad of main occupations obtained from the Taabo HDSS database were categorized into primary economic sector (i.e., making direct use of natural resources, such as farming), secondary economic sector (i.e., producing manufactured and other processed goods), and tertiary economic sector (i.e., producing services, such as education and health care), with housewives included in the primary sector as they are usually involved in (subsistence) farming. Socioeconomic household data were used to calculate an asset-based wealth index and deduce the inhabitants' socioeconomic status, according to an approach put forth in a World Bank publication
A Kruskal-Wallis test was performed to check for statistically significant (
Wilcoxon rank sum and Kruskal-Wallis test, χ2 and Fisher's exact test were employed, as appropriate, to check for statistically significant univariable associations between the different sociodemographic, parasitological, and Qol indicators. The outcome on QoL was further scrutinized in a multivariable linear regression analysis with sociodemographic data (i.e., age, sex, education, occupation, and socioeconomic status) and parasitological findings (i.e., schistosomiasis, soil-transmitted helminth infections, and malaria) as explanatory variables, considering also potential clustering of the results in interviewers and residential areas. A stepwise backward elimination procedure of non-significant explanatory factors was adopted to identify those variables most significantly influencing the participants' scores on QoL. In each iteration, the explanatory variable with the highest
Only participants with signed written informed consent and complete data records (i.e., responses to all questions, duplicate Kato-Katz thick smears, urine filtration, and RDT for malaria) were included in the final analysis. Participants with completed written informed consent and questionnaire, but incomplete parasitological results were included in an attrition analysis.
Overall, 255 adults were invited to participate in the study (
The study was carried out in June 2010, readily embedded in the second annual cross-sectional epidemiological survey of the Taabo health demographic surveillance system.
The educational level and the main sector of occupation are summarized in
Age | Sex | Number | Educational level | Main sector of occupation | |||||
(years) | asked | None | Primary | Secondary | Higher | Primary |
Secondary |
Tertiary |
|
school | school | education | |||||||
18–40 | Male | 37 | 15 | 11 | 9 | 2 | 31 | 1 | 5 |
Female | 29 | 19 | 5 | 4 | 1 | 23 | 0 | 6 | |
41–60 | Male | 36 | 12 | 10 | 13 | 1 | 26 | 1 | 9 |
Female | 48 | 30 | 8 | 8 | 2 | 29 | 4 | 15 | |
60+ | Male | 25 | 17 | 1 | 7 | 0 | 19 | 1 | 5 |
Female | 12 | 7 | 4 | 1 | 0 | 8 | 1 | 3 | |
All | Male | 98 | 44 | 22 | 29 | 3 | 76 | 3 | 19 |
All | Female | 89 | 56 | 17 | 13 | 3 | 60 | 5 | 24 |
All | Both | 187 | 100 | 39 | 42 | 6 | 136 | 8 | 43 |
Educational level and main sector of occupation among 187 adults interviewed in the Taabo health demographic surveillance system, south-central Côte d'Ivoire, in June 2010. Results are stratified by age and sex.
Participants being farmer, fisher, hunter, or housewife.
Participants being builder or artisan.
Participants being driver, housekeeper, watchman, merchant, trader, hairdresser, gastronome, healer, nurse, teacher, student, office worker, or policeman.
Results from the socioeconomic analysis are shown in
Asset | Percentage of participants possessing the asset | |||||
Total | Wealth quintiles | |||||
Most | Very | Poor | Less | Least | ||
poor | poor | (n = 38) | poor | poor | ||
(n = 39) | (n = 36) | (n = 37) | (n = 37) | |||
Type of housing | ||||||
Traditional hut | 31.0 | 66.7 | 63.9 | 18.4 | 5.4 | 0.0 |
Barrack | 1.1 | 5.1 | 0.0 | 0.0 | 0.0 | 0.0 |
Collective dwelling | 1.1 | 0.0 | 0.0 | 0.0 | 2.7 | 2.7 |
Simple house | 7.0 | 0.0 | 0.0 | 2.6 | 8.1 | 24.3 |
Row house | 18.7 | 0.0 | 2.8 | 5.3 | 40.5 | 46.0 |
Modern house | 22.5 | 0.0 | 11.1 | 42.1 | 32.4 | 27.0 |
Other housing | 18.7 | 28.2 | 22.2 | 31.6 | 10.8 | 0.0 |
People per sleeping room |
2.1 | 2.3 | 1.9 | 1.8 | 2.5 | 2.2 |
Main lighting at home | ||||||
Lantern | 29.4 | 87.2 | 58.3 | 0.0 | 0.0 | 0.0 |
Fix electric lighting | 65.8 | 0.0 | 30.6 | 100.0 | 100.0 | 100.0 |
Other lighting | 4.8 | 12.8 | 11.1 | 0.0 | 0.0 | 0.0 |
Energy source for cooking | ||||||
Wood | 80.8 | 100.0 | 94.4 | 100.0 | 81.1 | 27.0 |
Wood+coal | 10.7 | 0.0 | 0.0 | 0.0 | 13.5 | 40.5 |
Coal | 3.7 | 0.0 | 0.0 | 0.0 | 5.4 | 13.5 |
Gas+coal | 1.6 | 0.0 | 5.6 | 0.0 | 0.0 | 2.7 |
Gas | 3.2 | 0.0 | 0.0 | 0.0 | 0.0 | 16.2 |
Equipment | ||||||
Hand barrow | 9.6 | 0.0 | 11.1 | 5.3 | 13.5 | 18.9 |
Cistern | 32.6 | 30.8 | 22.2 | 50.0 | 29.7 | 29.7 |
Mobile phone | 67.4 | 20.5 | 80.6 | 65.8 | 78.4 | 94.6 |
Radio | 64.2 | 46.2 | 69.4 | 55.3 | 64.9 | 86.5 |
TV | 33.2 | 0.0 | 0.0 | 23.7 | 54.1 | 89.2 |
Pirogue | 6.4 | 2.6 | 8.3 | 10.5 | 8.1 | 2.7 |
Bicycle | 73.8 | 76.9 | 72.2 | 79.0 | 73.0 | 67.6 |
Moped | 13.9 | 0.0 | 0.0 | 13.2 | 13.5 | 43.2 |
Ventilator | 27.8 | 0.0 | 0.0 | 13.2 | 46.0 | 81.1 |
Fridge | 5.9 | 0.0 | 0.0 | 0.0 | 2.7 | 27.0 |
Freezer | 5.9 | 0.0 | 0.0 | 0.0 | 0.0 | 29.7 |
Overview of asset possession and the calculated socioeconomic status among 187 adults interviewed in the Taabo health demographic surveillance system, south-central Côte d'Ivoire, in June 2010.
Reports the average number of people per sleeping room in the respective wealth quintile.
Sex- and age-specific prevalence and intensity of helminth infection and
Parasitic infection (in %) | 18–40 years old | 41–60 years old | 60+ years old | All ages | ||||||
Male | Female | Male | Female | Male | Female | Male | Female | Both sexes | ||
(n = 37) | (n = 29) | (n = 36) | (n = 48) | (n = 25) | (n = 12) | (n = 98) | (n = 89) | (n = 187) | ||
|
Negative | 100.0 | 100.0 | 100.0 | 93.7 | 96.0 | 100.0 | 99.0 | 96.6 | 97.9 |
Light | 0.0 | 0.0 | 0.0 | 6.3 | 4.0 | 0.0 | 1.0 | 3.4 | 2.1 | |
Heavy | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
|
Negative | 97.3 | 100.0 | 100.0 | 93.7 | 100.0 | 100.0 | 99.0 | 96.6 | 97.9 |
Light | 2.7 | 0.0 | 0.0 | 4.2 | 0.0 | 0.0 | 1.0 | 2.3 | 1.6 | |
Moderate | 0.0 | 0.0 | 0.0 | 2.1 | 0.0 | 0.0 | 0.0 | 1.1 | 0.5 | |
Heavy | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
Hookworm |
Negative | 56.8 | 62.1 | 63.9 | 64.6 | 52.0 | 66.7 | 58.1 | 64.0 | 61.0 |
Light | 43.2 | 37.9 | 33.3 | 35.4 | 40.0 | 33.3 | 38.8 | 36.0 | 37.4 | |
Moderate | 0.0 | 0.0 | 2.8 | 0.0 | 8.0 | 0.0 | 3.1 | 0.0 | 1.6 | |
Heavy | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
|
Negative | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
Light | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
Moderate | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
Heavy | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
|
Negative | 94.6 | 96.5 | 100.0 | 100.0 | 96.0 | 91.7 | 96.9 | 97.8 | 97.3 |
Light | 5.4 | 3.5 | 0.0 | 0.0 | 4.0 | 0.0 | 3.1 | 1.1 | 2.2 | |
Moderate | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 8.3 | 0.0 | 1.1 | 0.5 | |
Heavy | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
Negative | 78.4 | 79.3 | 88.9 | 89.6 | 68.0 | 75.0 | 79.6 | 84.3 | 81.8 | |
Positive | 21.6 | 20.7 | 11.1 | 10.4 | 32.0 | 25.0 | 20.4 | 15.7 | 18.2 |
Prevalence and intensities of helminth and
Prevalence obtained by urine filtration method (one urine sample per person, single filtration).
Prevalence obtained by Kato-Katz method (one stool sample per person, duplicate Kato-Katz thick smears per sample).
Prevalence obtained by rapid diagnostic test (one RDT per person).
Thirteen different field enumerators and supervisors of the Taabo HDSS were involved in interviewing the study participants, with no statistically significant inter-observer variation in reported mean QoL scores (
The study was carried out in June 2010, readily embedded in the second annual cross-sectional epidemiological survey of the Taabo health demographic surveillance system. The different domain and overall quality of life (QoL) scores were obtained through questionnaire-based QoL interviews with the study participants. The participants' scores were measured on a scale from 0 to 100, as detailed on the y-axis of the figure, with higher scores indicating higher wellbeing. Domain 1, environmental wellbeing; domain 2, psychological wellbeing; domain 3, physical wellbeing; domain 4, social wellbeing. Box plot: the ends of the box represent the 25th and 75th percentile of the scores; the middle line represents the median; the lower whisker represents the lowest value between the lower quartile and the lower quartile−1.5*(interquartile range); the upper whisker represents the highest value between the upper quartile and the upper quartile+1.5*(interquartile range); the small squares, triangles, and crosses indicate outliers.
The mean domain and overall QoL scores in relation to sociodemographic and parasitological variables are shown in
Sociodemographic or | Mean domain and overall quality of life score | |||||||||
parasitological determinants | Domain 1 | Domain 2 | Domain 3 | Domain 4 | Quality of life | |||||
Sex: male | 49.2 | 64.5 | 73.0 | 86.7 | 65.0 | |||||
Sex: female | 52.1 | 0.275 | 60.5 | 0.180 | 69.5 | 0.267 | 83.7 | 0.496 | 62.8 | 0.385 |
Age: 18–40 years | 48.9 | 63.5 | 74.0 | 87.6 | 65.2 | |||||
Age: 41–60 years | 50.3 | 61.0 | 70.1 | 82.3 | 62.5 | |||||
Age: over 60 years | 54.2 | 0.424 | 64.3 | 0.467 | 69.4 | 0.614 | 87.8 | 0.554 | 65.0 | 0.618 |
Education: no | 51.1 | 62.7 | 68.9 | 87.8 | 63.3 | |||||
Education: primary school | 45.9 | 62.6 | 76.6 | 83.8 | 64.7 | |||||
Education: secondary school | 50.9 | 61.3 | 71.4 | 81.4 | 63.3 | |||||
Education: higher education | 70.4 | 0.043 |
68.9 | 0.859 | 77.0 | 0.423 | 80.6 | 0.234 | 73.0 | 0.393 |
Occupation: primary sector | 48.3 | 61.9 | 70.5 | 84.8 | 62.8 | |||||
Occupation: secondary sector | 56.9 | 64.2 | 70.8 | 91.7 | 66.1 | |||||
Occupation: tertiary sector | 56.6 | 0.050 | 64.5 | 0.717 | 74.0 | 0.464 | 85.7 | 0.980 | 67.2 | 0.192 |
Socioeconomic status: most poor | 47.2 | 64.1 | 75.3 | 91.0 | 65.4 | |||||
Socioeconomic status: very poor | 46.6 | 59.8 | 72.6 | 82.4 | 62.6 | |||||
Socioeconomic status: poor | 47.2 | 61.8 | 65.9 | 85.5 | 60.6 | |||||
Socioeconomic status: less poor | 49.4 | 58.0 | 68.3 | 79.3 | 60.7 | |||||
Socioeconomic status: least poor | 62.6 | 0.006 |
69.0 | 0.091 | 74.4 | 0.071 | 87.8 | 0.392 | 70.3 | 0.063 |
50.6 | 62.8 | 71.7 | 85.8 | 64.2 | ||||||
47.2 | 0.926 | 50.0 | 0.168 | 56.0 | 0.126 | 62.5 | 0.375 | 51.9 | 0.223 | |
50.9 | 62.8 | 71.7 | 85.8 | 64.3 | ||||||
33.3 | 0.251 | 50.0 | 0.191 | 56.0 | 0.114 | 62.5 | 0.180 | 47.7 | 0.130 | |
Hookworm: negative | 54.4 | 62.6 | 71.9 | 87.9 | 65.4 | |||||
Hookworm: positive | 44.6 | 0.002 |
62.6 | 0.895 | 70.5 | 0.702 | 81.3 | 0.143 | 61.6 | 0.114 |
50.6 | 62.6 | 71.3 | 85.3 | 63.9 | ||||||
NA | NA | NA | NA | NA | NA | NA | NA | NA | NA | |
64.4 | 77.3 | 79.1 | 93.3 | 75.8 | ||||||
50.2 | 0.070 | 62.2 | 0.105 | 71.1 | 0.233 | 85.1 | 0.434 | 63.6 | 0.060 | |
50.2 | 62.6 | 70.8 | 85.8 | 63.8 | ||||||
52.1 | 0.514 | 62.6 | 0.979 | 73.5 | 0.510 | 82.8 | 0.308 | 64.7 | 0.494 |
Mean domain and overall quality of life scores in relation to sociodemographic determinants among 187 adults in the Taabo health demographic surveillance system, south-central Côte d'Ivoire, in June 2010.
Domain 1, environmental wellbeing; domain 2, psychological wellbeing; domain 3, physical wellbeing; domain 4, social wellbeing.
NA, not applicable.
= statistically significant (
The wealth index (
Explanatory variable | Coeff. | 95% CI | |
Sex |
−3.5 | (−7.3, 0.2) | 0.067 |
Working in secondary or tertiary sectors |
3.8 | (−0.7, 8.3) | 0.094 |
Wealth index |
1.2 | (0.1, 2.3) | 0.034 |
−16.4 | (−29.2, −3.7) | 0.011 |
|
Hookworm infection of any intensity |
−3.9 | (−8.0, 0.2) | 0.061 |
−12.6 | (−24.4, −0.9) | 0.035 |
A multivariable linear regression model with a stepwise backward elimination procedure was adopted in order to identify those explanatory variables, which most significantly influence the study participants' quality of life (QoL) scores. The explanatory variables and indicators of the multivariable linear regression model at each step of the backward elimination procedure are shown in the supporting information (
CI, confidence interval.
= statistically significant (
Reference category: male.
Reference category: primary sector.
Continuous variable.
Reference category: no
Reference category: no hookworm infection.
Reference category: no
Comparison of participants who were included in the final analysis and participants who gave written informed consent and completed the questionnaire, but dropped out due to incomplete parasitological data, revealed no statistically significant differences in sociodemographic characteristics (
Sociodemographic factor | Included | Excluded | |
(n = 187) | (n = 61) | ||
Sex: male | 98 | 25 | |
Sex: female | 89 | 36 | 0.121 |
Age: 18–40 years | 66 | 27 | |
Age: 41–60 years | 84 | 28 | |
Age: over 60 years | 37 | 6 | 0.163 |
Education: no | 100 | 34 | |
Education: primary school | 39 | 18 | |
Education: secondary school | 42 | 8 | |
Education: higher education | 6 | 1 | 0.277 |
Occupation: primary sector | 136 | 50 | |
Occupation: secondary sector | 8 | 0 | |
Occupation: tertiary sector | 43 | 11 | 0.164 |
Socioeconomic status: most poor | 33 | 18 | |
Socioeconomic status: very poor | 35 | 14 | |
Socioeconomic status: poor | 42 | 8 | |
Socioeconomic status: less poor | 39 | 10 | |
Socioeconomic status: least poor | 38 | 11 | 0.189 |
The sociodemographic determinants of the 248 individuals who participated in the questionnaire survey were collected in the Taabo health demographic surveillance system, south-central Côte d'Ivoire, in June 2010.
Quality of life indicator | Included | Excluded | |
(n = 187) | (n = 61) | ||
Domain 1: environmental wellbeing | 50.6 | 49.6 | 0.770 |
Domain 2: psychological wellbeing | 62.6 | 60.9 | 0.464 |
Domain 3: physical wellbeing | 71.3 | 68.0 | 0.213 |
Domain 4: social wellbeing | 85.3 | 83.3 | 0.632 |
Overall quality of life | 63.9 | 62.3 | 0.468 |
The domain and overall quality of life (QoL) scores of the 248 individuals who participated in the questionnaire survey were collected in the Taabo health demographic surveillance system, south-central Côte d'Ivoire, in June 2010.
We present an analysis from a QoL questionnaire survey conducted alongside the 2010 cross-sectional epidemiological survey and deworming campaign in the Taabo HDSS in south-central Côte d'Ivoire. Results of a multivariable linear logistic regression model revealed that adults' QoL is reduced considerably among those infected with different species of helminths, regardless of the intensity of infection. Indeed, we found that the perceived QoL among adults infected with
Our results have to be interpreted with caution, but raise many interesting issues. As a first critical point, it has to be considered that the sampling of the current study depended on a stratified random sampling. Starting in mid-2009, our team pursued a yearly cross-sectional epidemiological survey among approximately 7% of the people who were under demographic and health surveillance in the Taabo HDSS. The present study was linked to the June 2010 cross-sectional survey, using a sub-sample (i.e., all head of households plus a second randomly selected person of the same household but the opposite sex to maintain gender balance). Given our sampling approach and in view of operational and financial considerations, no formal sample size calculation was made for the present study.
Second, our final sample size of 187 individuals was relatively small and the compliance rate of 73.3% suboptimal. However, somewhat higher drop-out rates had to be expected as the participants were adults, many of whom were illiterate. Compared to school-aged children, adults seemed to be somewhat reluctant or ashamed to provide any stool or urine samples. Importantly though, the attrition analysis revealed no statistically significant differences in the available indicators between the included and excluded adults, and hence no selection bias seems to have been introduced by the drop-outs.
Third, the absence of a statistically significant inter-observer variation suggests that our questionnaire results are reliable. Cronbach's alpha as well as the highly significant positive correlation between the calculated summary scores on QoL based on all questions and the QoL ratings directly expressed by the participants in the final question of the questionnaire indicate internal consistency and validity of the QoL scores.
Fourth, the parasitological diagnosis was based on single stool and urine samples with duplicate Kato-Katz thick smear examinations and single urine filtration, respectively. There is a large body of work demonstrating that multiple sampling or a combination of diagnostic methods result in more accurate diagnosis
Fifth, the mean domain and overall QoL scores displayed in
Sixth, the effects of the sociodemographic determinants on the mean domain and overall QoL scores were somewhat less clear in the univariable comparison as summarized in
Seventh, there were only a few people infected with
Eighth, the here presented decrease of 16 points on the 0 to 100 QoL scale due to
In conclusion, we found consistent and significant results on the effect of schistosomiasis, soil-transmitted helminthiasis, and sociodemographic determinants on adults' QoL in rural Côte d'Ivoire. It is conceivable that helminth-infected adults in the present study suffered from advanced chronic infections and therefore reported notable losses in QoL. Our results warrant further investigation on the disability induced by helmintic infections and further probing of the usefulness and applicability of generic QoL questionnaires in this regard. Future studies should adhere to a more rigorous sampling strategy and sample size calculation, optimally in a randomized trial design, which allows for an improved control of potential confounders and the assessment of interactions due to combined infections. Furthermore, they should consider additional qualitative research to further explore the local residents' concept about QoL, additional verification of the QoL questionnaire's reliability and validity (e.g., test-retest comparison, comparison of questionnaire results with objectively measurable indicators
(DOC)
(DOC)
(DOC)
(DOC)
We thank all the individuals living in the Taabo HDSS for their participation in the annual cross-sectional epidemiological survey pursued in mid-2010, and particularly for participating in the present study. We are indebted to all the local political and health authorities for their kind collaboration. Furthermore, we would like to acknowledge the invaluable support from all the laboratory technicians and the entire Taabo HDSS staff. We are grateful to Dr. Mirko Winkler for assistance with figure layout. The final version of this manuscript benefited from thorough reviews and a series of helpful comments and suggestions from three anonymous reviewers.