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Validation of the Primary Care Patient Measure of Safety (PC PMOS) questionnaire
  1. Sally J Giles1,
  2. Sahdia Parveen2,
  3. Andrea L Hernan3
  1. 1 NIHR Greater Manchester Primary Care Patient Safety Translational Research Centre, University of Manchester, Manchester, UK
  2. 2 Faculty of Health Studies, University of Bradford, Bradford, UK
  3. 3 Deakin Rural Health, Deakin University, Warrnambool, Victoria, Australia
  1. Correspondence to Dr Sally J Giles, NIHR Greater Manchester Primary Care Patient Safety Translational Research Centre, University of Manchester, Manchester M13 9PL, UK; sally.giles{at}


Background The Primary Care Patient Measure of Safety (PC PMOS) is designed to capture patient feedback about the contributing factors to patient safety incidents in primary care. It required further reliability and validity testing to produce a robust tool intended to improve safety in practice.

Method 490 adult patients in nine primary care practices in Greater Manchester, UK, completed the PC PMOS. Practice staff (n = 81) completed a survey on patient safety culture to assess convergent validity. Confirmatory factor analysis (CFA) assessed the construct validity and internal reliability of the PC PMOS domains and items. A multivariate analysis of variance was conducted to assess discriminant validity, and Spearman correlation was conducted to establish test–retest reliability.

Results Initial CFA results showed data did not fit the model well (a chi-square to df ratio (CMIN/DF) = 5.68; goodness-of-fit index (GFI) = 0.61, CFI = 0.57, SRMR = 0.13 and root mean square error of approximation (RMSEA) = 0.10). On the basis of large modification indices (>10), standardised residuals >± 2.58 and assessment of item content; 22 items were removed. This revised nine-factor model (28 items) was found to fit the data satisfactorily (CMIN/DF = 2.51; GFI = 0.87, CFI = 0.91, SRMR = 0.04 and RMSEA = 0.05). New factors demonstrated good internal reliability with average inter-item correlations ranging from 0.20 to 0.70. The PC PMOS demonstrated good discriminant validity between primary care practices (F = 2.64, df = 72, p < 0.001) and showed some association with practice staff safety score (convergent validity) but failed to reach statistical significance (r = −0.64, k = 9, p = 0.06).

Conclusion This study led to a reliable and valid 28-item PC PMOS. It could enhance or complement current data collection methods used in primary care to identify and prevent error.

  • patient safety
  • quality improvement
  • primary care
  • validation
  • surveys

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  • Contributors SJG and ALH conceived and designed the study. SJG obtained funding for the study and was responsible for practice and patient recruitment and data collection. SP was responsible for the data analysis, and writing specific sections of the manuscript. SJG and ALH created the first draft of the manuscript and were responsible for its revisions. All authors read and approved the final version of the manuscript.

  • Funding This research was funded by the NIHR Greater Manchester Patient Safety Translational Research Centre.

  • Disclaimer The National Institute for Health Research (NIHR) Greater Manchester Patient Safety Translational Research Centre (Greater Manchester PSTRC) is a partnership between The University of Manchester and Salford Royal NHS Foundation Trust. This manuscript summarises independent research funded by the NIHR Greater Manchester PSTRC. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

  • Competing interests None declared.

  • Patient consent Obtained.

  • Ethics approval NHS Health Research Authority (HRA) approval (project no. 16/SS/0096).

  • Provenance and peer review Not commissioned; externally peer reviewed.