A patient-reported experience measure for community pharmacy including development of a short-form: The perceived service quality scale.

Background: The perceived service quality scale (pSQS) is a patient-reported experience measure (PREM) previously developed for measuring perceived service quality (pSQ) in community pharmacies. While measuring pSQ is feasible, further psychometric evaluation of the pSQS is warranted. In addition, the length of the 20-item pSQS may lead to fatigue among patients. It remains to be determined whether a short form of the pSQS has acceptable psychometric properties.

Objectives: The aim of this study was to psychometrically test the pSQS with a specific focus on making scoring recommendations and developing a short form pSQS with acceptable psychometric properties.

Methods: Participants were recruited either in community pharmacies or via an online panel to complete a questionnaire including the pSQS. Confirmatory factor analyses (CFA) were conducted using robust statistics, including tests of factorial invariance. Alternative models were tested including a bifactor model. Spearman's correlation was used to conduct test-retest analyses on responses obtained one month apart.

Results: Data were analysed from 319 participants recruited in-store and 303 participants recruited online, 86 participants providing test-retest reliability. Tests of factorial invariance indicated that the pSQS is stable across settings. The most parsimonious and best-fitting solution was obtained with a 19-item bifactor model with 5 factors plus a "general" factor. Factor scores obtained from the "general" factor explained sufficient variance and are unlikely to be excessively biased in regression models. A short-form 6-item scale (pSQ-SF6) demonstrated acceptable psychometric properties and similar predictive capacity to the original pSQS for patient loyalty intentions. Test-retest analyses indicated acceptable reliability for pSQS and PSQ-SF6.

Conclusion: This study confirms that the pSQS has acceptable psychometric properties including temporal stability. It is recommended that a 19-item pSQS be used to obtain a comprehensive overview of patients' pSQ. The short-form pSQ-SF6 is suitable as a community pharmacy PREM.