Primary care outcomes questionnaire: psychometric testing of a new instrument

Background Patients attend primary care for many reasons and to achieve a range of possible outcomes. There is currently no Patient Reported Outcome Measure (PROM) designed to capture these diverse outcomes, and trials of interventions in primary care may thus fail to detect beneficial effects. Aim This study describes the psychometric testing of the Primary Care Outcomes Questionnaire (PCOQ), which was designed to capture a broad range of outcomes relevant to primary care. Design and setting Questionnaires were administered in primary care in South West England. Method Patients completed the PCOQ in GP waiting rooms before a consultation, and a second questionnaire, including the PCOQ and seven comparator PROMs, after 1 week. Psychometric testing included exploratory factor analysis on the PCOQ, internal consistency, correlation coefficients between domain scores and comparator measures, and repeated measures effect sizes indicating change across 1 week. Results In total, 602 patients completed the PCOQ at baseline, and 264 (44%) returned the followup questionnaire. Exploratory factor analysis suggested four dimensions underlying the PCOQ items: health and wellbeing, health knowledge and self-care, confidence in health provision, and confidence in health plan. Each dimension was internally consistent and correlated as expected with comparator PROMs, providing evidence of construct validity. Patients reporting an improvement in their main problem exhibited small to moderate improvements in relevant domain scores on the PCOQ. Conclusion The PCOQ was acceptable, feasible, showed strong psychometric properties, and was responsive to change. It is a promising new tool for assessment of outcomes of primary care interventions from a patient perspective.