Agreement found between self-reported and health insurance data on physician visits comparing different recall lengths

ObjectiveTo analyze the impact of different recall lengths on agreement between self-reported physician visits and those documented in health insurance data applying an experimental design.Study Design and SettingWe randomly assigned 432 patients with diabetes to one of two versions of a written survey, each asking about the number of physician visits over a 3- or 6-month recall period. Health insurance data were linked individually.ResultsIn both groups, the mean number of self-reported physician visits per month was lower than in the insurance data, with a larger difference in the 6-month group (−0.9; 95% CI −1.0, −0.7) than in the 3-month group (−0.5; −0.7; −0.2), difference between the two groups: 0.4 (0.1-0.7; P = 0.009). The percentage of participants with correct reporting was small and did not differ largely between the two groups (6.5% and 9.3%). However, there was more overreporting in the 3-month group (25.6% vs. 11.1%).ConclusionsShorter recall periods may produce more accurate results when estimating the mean number of physician visits. However, this may be driven not by a more accurate reporting, but by a higher proportion of respondents that overreported and a lower proportion of respondents that underreported, when compared to the longer reporting period.