Association of medical tests use with care continuity in primary care service: evidence from the Department of Veterans Affairs.

Background: Continuity of care (CoC) is an important component of health care delivery that can have cost implications and improve patient outcomes. We analysed data obtained from the Department of Veterans Affairs to examine the relationship between CoC and use of image-oriented diagnostic tests in patients with comorbid chronic conditions.

Methods: A longitudinal, retrospective cohort study involving participants ≥18 years old, with comorbid diabetes and chronic kidney disease. We used a multivariate linear regression model to test whether greater care continuity, measured using a care continuity index (CCI), is associated with less frequent use of diagnostic tests.

Results: Total of 267,442 patients and 8,142,036 tests were included. Of the diagnostic tests we chose to evaluate, the 4 most frequently ordered tests were X-ray (45.6%), electrocardiogram (EKG, 16.8%), computerized tomography (CT, 13.4%), and magnetic resonance imaging (MRI, 3.4%). Overall, greater CCI was associated with fewer use of tests (P < 0.001). A 1 standard deviation (SD, 0.27) increase in CCI was associated with 4.2% decrease (P < 0.001) in number of tests. But a mixed pattern existed. For X-ray and EKG, greater continuity was associated with less testing, 6.2% (P < 0.001) and 3.3% (P < 0.05) reductions, respectively. Whereas, for CT and MRI, greater continuity was associated with more testing, 2.3% (P < 0.001) and 1.4% increases (P < 0.01), respectively.

Conclusion: Overall, greater CoC was associated with fewer use of tests, representing a greater presumed efficiency of care. This has implications for designing health care delivery.