Chronic respiratory diseases (CRDs), such as asthma and chronic obstructive pulmonary disease (COPD), are among the leading non-communicable diseases (NCDs) worldwide. However, diagnosing CRDs in low-income and middle-income countries (LMICs) remains challenging due to limited access to spirometry and trained professionals. Aggravating the burden, CRDs often coexist with other NCDs, increasing healthcare costs, reducing quality of life and elevating mortality. These challenges highlight the need for simple case-finding approaches for CRDs, such as the COPD in Low-Income and Middle-Income Countries Assessment (COLA-6) questionnaire, to support prompt identification and appropriate care within NCD services in LMICs.

To evaluate the discriminative accuracy, feasibility and implementation of the COLA-6 questionnaire in identifying and managing CRDs in Brazilian Primary Healthcare (PHC) services for NCDs.

The Multimorbidity Approach for REspiratory Solutions (MARES) study consists of three work packages to be conducted in PHC services in São Carlos/SP and São Paulo/SP, Brazil.

MARES-1: A cross-sectional observational study enrolling 859 individuals with at least one NCD receiving care in PHC. The COLA-6 questionnaire will be administered by the research team and compared with quality-assured spirometry. The Chronic Airways Assessment Test (CAAT), Asthma Control Questionnaire (ACQ-7) and fractional exhaled nitric oxide (FeNO) will also be assessed. The diagnostic performance of COLA-6 for identifying CRDs—including COPD, asthma, preserved ratio impaired spirometry, restriction and overlaps—will be assessed using area under receiver operating characteristic curves and 95% CIs.

MARES-2: A cross-sectional observational study enrolling 20 healthcare professionals (physicians, physiotherapists, community health agents and nurses) from five PHC services. These professionals will apply the COLA-6 during routine NCD care to a total sample of 1000 patients. Qualitative interviews will be conducted to explore barriers and facilitators to the implementation of COLA-6, using deductive thematic analysis.

MARES-3: A longitudinal, prospective observational study in which patients from MARES-1 and MARES-2 will be reassessed at 6-month follow-up. A total sample of 473 participants with abnormal spirometry, a diagnosis of CRD or high risk for CRDs is expected. Participants will undergo spirometry, and a subset will be interviewed to explore their healthcare experiences through qualitative thematic analysis. Access to diagnostic and treatment services in Brazil will be assessed. Changes in spirometry values, FeNO, CAAT and ACQ-7 scores from baseline to 6 months in patients from MARES-1 will be analysed.

This study has been approved by the Ethics Committees of Federal University of São Carlos and University of Santo Amaro (UNISA). Ethical approval was also granted by the University College London. Results will be disseminated through peer-reviewed medical journals and presentations at international conferences. Results will improve identification of CRDs, addressing a significant gap in current PHC settings.

NCT07050823/NCT07093021/NCT07134855.