Aim, design and setting of the study

The CAMP study (Chronic health Assessment and Mapping of Proximity needs) is designed as a cross-sectional, observational, non-interventional study employing a mixed-methods approach. It will be conducted in multiple rural and semi-rural municipalities within the Campania region of Southern Italy, in collaboration with local health authorities and social services. For the purposes of this study, underserved rural/semi-rural areas are defined as municipalities with a medium/low population density (<150 inhabitants/km²), located more than a 30-minute drive from the nearest tertiary care hospital, and with below-average availability of health and social services, based on regional planning indicators. The classification also considers additional socioeconomic vulnerability factors, such as population aging and per capita income below the regional average. These operational criteria ensure transparency and replicability in the selection of recruitment areas.

The primary aim is to assess the health and social care needs of adults with chronic conditions residing in underserved areas, to inform future proximity-based care planning.

Sample size, inclusion and exclusion criteria

The sample size was calculated assuming a 30% prevalence of patients reporting significant barriers to healthcare access, with a 5% margin of error and 95% confidence level. This prevalence was adopted as a conservative assumption, consistent with recent European evidence reporting unmet healthcare needs in the range of 25–35% among chronically ill and rural populations [5; 7,8]. Considering a potential dropout or non-response rate of 20–25%, we aim to enroll approximately 400–500 participants.

Inclusion criteria

Age ≥ 18 years;

Clinical diagnosis of one or more chronic diseases (e.g., COPD, diabetes, heart failure, chronic kidney disease, dementia);

Registered with a general practitioner (GP) in the selected territories;

Ability to provide informed consent (directly or with caregiver assistance).

Exclusion criteria

Current hospitalization or acute clinical instability;

Severe cognitive impairment without caregiver support, assessed on the basis of an existing clinical diagnosis documented in medical records or confirmed by the general practitioner. In doubtful cases, GP clinical judgment will be used to exclude patients who are unable to provide informed consent or actively participate in data collection;

Refusal to participate.

Characteristics of participants and sample selection

Eligible participants will be identified through GP registries and social service records in the participating municipalities. There is no randomization or blinding, given the observational nature of the study. Recruitment will be coordinated by GPs and social workers, who will provide information sheets and collect written informed consent. We acknowledge that GP workload and the difficulty of reaching the most isolated individuals may represent practical barriers to recruitment. To mitigate these challenges, additional strategies will be implemented, including outreach activities through community organizations, collaboration with municipal health coordinators, and the use of snowball sampling when appropriate. These measures aim to maximize recruitment feasibility and ensure the inclusion of hard-to-reach populations.

Study procedures and outcomes

This study does not include any interventions, experimental treatments, or comparison arms. It solely involves administering validated questionnaires and conducting interviews. After providing written informed consent, participants will be offered the choice to complete data collection either immediately at the GP’s office or social services site, or at a later scheduled appointment with the research team. Quantitative questionnaires and qualitative interviews may be administered during the same session or, when more convenient for the participant, in separate encounters within a two-week period. While the preferred mode is face-to-face, flexibility is ensured through the availability of telephone or videoconference options, particularly for participants residing in remote areas or with mobility limitations. These procedures aim to maximize feasibility, inclusiveness, and adherence across diverse rural settings.

Quantitative data will be gathered using the following validated instruments:

SF-36: to assess health-related quality of life [11].

EQ-5D: to measure health status and utility [12].

Barthel Index: to evaluate functional autonomy in activities of daily living [13].

MSPSS: to assess perceived social support [14].

Qualitative data will be collected through semi-structured interviews focused on patients’ experiences with care access, perceived needs, and expectations [15]. For the qualitative component, a purposive subsample of approximately 40–50 participants will be selected to ensure diversity in age, sex, type of chronic condition, and degree of geographic isolation. Interviews will be conducted until thematic saturation is reached, defined as the point at which no new codes or themes emerge from successive interviews. The semi-structured interview guide will include broad thematic areas such as: (i) experiences and barriers in accessing healthcare and social services; (ii) perceptions of care coordination and integration; (iii) psychosocial and family support needs; (iv) expectations and suggestions for proximity-based care models (e.g., community hospitals, telemedicine). The final wording of questions may be refined following piloting, but these domains directly reflect the study objectives and gaps identified in the literature on unmet needs among rural populations.

The primary and secondary outcomes of the study are summarized in Table 1.

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Table 1. Primary and secondary outcomes of the study.

https://doi.org/10.1371/journal.pone.0335196.t001

Data management

All data will be anonymized and entered into a secure electronic database with controlled access, compliant with EU GDPR regulations. Data will be stored for at least 5 years following study completion.

Safety considerations

No interventions or experimental treatments will be performed. Participants will only complete questionnaires and interviews, ensuring minimal risk.

Statistical analysis

Descriptive statistics (means, SDs, frequencies) will summarize participant characteristics. Bivariate analyses (t-tests, ANOVA, chi-square) will explore associations among clinical and social variables. Multivariable logistic and linear regression models will identify predictors of poor quality of life, reduced autonomy, and limited access to care. Qualitative data from interviews will be analyzed using thematic analysis with independent coders to ensure triangulation. The study will adopt a sequential explanatory mixed-methods design. Quantitative analyses will first provide prevalence estimates and associations between clinical, functional, and social variables. Subsequently, qualitative interviews will be used to contextualize and deepen the understanding of these findings. Integration will occur at the interpretation stage through triangulation, whereby themes emerging from the qualitative analysis will be compared and contrasted with quantitative results to identify convergences, divergences, and complementarities. This approach ensures that the qualitative strand enriches the quantitative findings, providing a more comprehensive understanding of unmet needs in rural chronic care.

Ethical considerations

The study was approved by the Campania 2 Ethics Committee (Approval no. 0013474−2025, 21 May 2025). All participants will provide written informed consent. The study was registered on the Open Science Framework (DOI: https://doi.org/10.17605/OSF.IO/YHD87).

Study status and timeline

At the time of manuscript submission, participant recruitment has not yet begun. The recruitment phase is planned to start in September 2025, with an estimated end by December 2025. Data collection will continue until March 2026, and results are expected to be available by June–July 2026. No recruitment or data collection activities have been undertaken prior to registration or submission. Qualitative interviews will be conducted with a purposive subsample of approximately 40–50 participants rather than with the entire cohort, thereby reducing the workload. Should recruitment or interview scheduling take longer than anticipated, the timeline allows for a potential three-month extension (until June 2026) to ensure adequate coverage. This contingency plan is designed to safeguard feasibility without compromising data completeness or methodological rigor.