Effect of Automobile Travel Time Between Patients' Homes and Ophthalmologists' Offices on Screening for Diabetic Retinopathy.

PURPOSE: The accessibility of ophthalmologists appears to influence the quality of screening for diabetic retinopathy (DR). The principal objective of this study was to analyze the effect of automobile travel time to the closest ophthalmologist on the time to DR screening.

METHODS

This historical cohort study used reimbursement databases from the principal national health insurance fund. Patients were included if they had been reimbursed at least thrice for oral antidiabetic medications in the 12 months before the study start date. Patients were followed up from January 1, 2008, for 4 years. The expected event was a DR screening by an ocular fundus examination. The automobile travel time to the nearest ophthalmologist was calculated by the distance between communes, estimated by appropriate software. A Kaplan-Meier curve and a multivariate Cox model were used to model the effect of travel time on the time until DR screening. A sensitivity analysis of travel time described the results of the Cox model.

RESULTS

At the start of 2008, 6,573 patients living in 328 different municipalities were included. The multivariate model found that patients living 60 min or more away from an ophthalmologist had a lower instantaneous probability of DR screening than those living <30 min away (adjusted risk ratio = 0.82; 95% confidence interval 0.71-0.95; p = 0.009). The sensitivity analysis showed that this difference became significant at 35 min of travel time.

CONCLUSION

Increased automobile travel time for patients with diabetes to the nearest ophthalmologist was associated with a longer time to DR screening.