Mitigating Chronic Respiratory Disease Through the Lens of Multi-Morbidity

This study aims to evaluate the discriminative capacity of the COLA-6 questionnaire in identifying individuals with chronic respiratory diseases (CRDs) who attend primary health care (PHC) services in Brasil, for the treatment of other long-term conditions (LTCs). To achieve this, the investigators will conduct a cross-sectional observational study enrolling 859 individuals with one or more existing LTCs who are receiving care in PHC services. The COLA-6 questionnaire will be administered, and its results will be compared to gold-standard post-bronchodilator spirometry. The performance of the case-finding tool will be assessed using the area under a receiver operating characteristic (ROC) curve.

This study will be conducted in PHC services, including Basic Health units (BHUs) and Family Health Units (FHUs), located in the municipalities of São Carlos and São Paulo, both situated in the state of São Paulo, Brasil. The municipality of São Carlos has a population of 254,857 inhabitants and a gross domestic product (GDP) of R$55,044.88 per capita, with 34 PHC units. In contrast, São Paulo, the state capital, has a population of 11,451,999 inhabitants and a per capita GDP of R$66,872.84, and is served by 471 PHC units.

Individuals will be recruited from PHC services, including BHUs and FHUs, located in the municipalities of São Carlos and São Paulo, Brasil. Eligible individuals with NCDs will be identified through three main strategies: (1) individuals attending BHUs/FHUs with an established LTC profile (e.g., scheduled consultations or monitoring for hypertension, diabetes, etc.); (2) individuals with LTCs identified by community health agents through proactive outreach; and (3) individuals with LTCs who attend PHC services and become aware of the study through passive recruitment methods such as posters, information shared by staff or other patients, and invitations extended during service days. Additionally, posters containing the research team's contact information will be displayed, and invitations will be extended during service days at the BHUs/FHUs. All recruitment procedures will be conducted in accordance with ethical principles, ensuring the protection of participants' rights to privacy and autonomy.

Data collection will be conducted in a single visit by a member of the UFSCar research team. All eligible participants will provide written Informed Consent prior study procedures. The following procedures will be carried out:

Initial assessment;

Application of case-finding tools questionnaires:

COLA-6 questionnaire; Symptom-Based questionnaire (SBQ); Exhaled fraction of nitric oxide (FeNO) measurement; Spirometry (pre- and post-bronchodilator);

Application of disease-specific questionnaires:

Chronic Airways Assessment Test (CAAT) for all individuals with abnormal spirometry; Asthma Control Questionnaire (ACQ-7) for individuals with isolated or overlapping asthma; provision of basic information on access to downstream healthcare services for diagnosis and treatment of participants identified with abnormal spirometry.

Participants will be classified based on spirometry and FeNO results into two groups, primarily according to the recommendations of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) and the Global Initiative for Asthma (GINA):

Abnormal Spirometry: Includes COPD, asthma, asthma-COPD overlap, PRISm, restriction patterns, asthma-PRISm overlap and asthma-restriction overlap.

Normal Spirometry: Participants without lung function abnormalities.

The sample size calculation was based on the performance of the COLA-6 questionnaire for diagnosing COPD in the investigators' previous GECo study where COPD prevalence was 9.4%. With these assumed values, a minimum sample size of n=859 individuals will allow the investigators to estimate the area under (AUC) the receiver operating characteristic (ROC) curve to within 4.5% (based on a 95% confidence interval). According to prevalence studies for CRDs in Brasil, the investigators calculate the ability to identify approximately N=146 individuals with COPD, N=77 with asthma, and N=86 with Preserved Ratio Impaired Spirometry (PRISm) in this study, therefore an estimated sample of N=309 with abnormal spirometry and N=550 with normal spirometry. The investigators will case-find in more people if the expected prevalence is lower to reach these targets.

The investigators will summarise the demographic, and clinical characteristics of participants overall and by those with normal and abnormal spirometry. Based on spirometry results, the investigators will report the prevalence of COPD, asthma, PRISm and restriction, alone and in combination, with 95% confidence intervals. For the primary analysis, the investigators will calculate the AUC of the ROC curves for COLA-6 compared with the gold standard spirometry diagnosis separately for combined CRDs, asthma, COPD and PRISm. Using the previously published threshold for COLA-6 scores of ≥4, the investigators will also calculate sensitivity, specificity, and negative and positive predictive values. In addition, based on the ROC curve the investigators will identify the COLA-6 score threshold that achieves sensitivity of at least 90%. All estimates will be reported with 95% confidence intervals.

Full ethical approval was obtained from the Ethics Committee of the Federal University of São Carlos and UNISA (reference number: MARES-1: 85805425.4.1001.5504) and UCL as described above.

The MARES project is funded by the UK NIHR (project reference 303125) using UK international development funding from the UK Government to support global health research. The views expressed in this publication are those of the the investigators and not necessarily those of the NIHR or the UK government.