Comparison of two methods of collecting healthcare usage data in chiropractic clinics: patient-report versus documentation in patient files

BACKGROUND: The use of patient-reported questionnaires to collect information on costs associated with routine healthcare services, such as chiropractic, represents a less labour intensive alternative to retrieving these data from patient files. The aim of this paper was to compare patient-report versus patient files for the collection of data describing healthcare usage in chiropractic clinics. METHODS: As part of a prospective single cohort multi-centre study, data on the number of visits made to chiropractic clinics determined using patient-reported questionnaires or as recorded in patient files were compared three months following the start of treatment. These data were analysed for agreement using the Intraclass Correlation Coefficient (ICC) and the 95% Limits of Agreement. RESULTS: Eighty-nine patients that had undergone chiropractic care were included in the present study. The two methods yielded an ICC of 0.83 (95% CI = 0.75 to 0.88). However, there was a significant difference between the data collection methods, with an average of 0.6 (95% CI = 0.25 to 1.01) additional visits reported in patient files. The 95% Limits of Agreement ranged from 3 fewer visits to 4 additional visits in patient files relative to the number of visits recalled by patients. CONCLUSION: There was some discrepancy between the number of visits made to the clinic recalled by patients compared to the number recorded in patient files. This should be taken into account in future evaluations of costs of treatments.