Patterns of Clinical Care Subsequent to Nonindicated Vitamin D Testing in Primary Care.

Background: Exponential increases in nonindicated, low-value vitamin D testing have been reported over the past 15 years. Downstream effects of such testing have not been well quantified. Methods: The purpose of this study was to describe patterns of vitamin D testing within primary care of a large regional health system and to explore downstream health service utilization subsequent to nonindicated testing. Instances of vitamin D testing in 2015 were obtained by an electronic health record-automated search. A subset of patients for whom vitamin D testing was classified as nonindicated was identified, and vitamin D-related service utilization was tracked for 24 months. Results: Of the 77,836 adult primary care patient records identified in 2015, vitamin D tests were conducted on 8,042 (10.3%), with 24.3% of tests yielding abnormal results. In the nonindicated test subset (n = 574), substantial clinical variability was illustrated by 85 care pathways and 26 vitamin D prescriptions. Forty-five percent of abnormal vitamin D lab tests were not followed up with repeat vitamin D tests. Vitamin D-related services (laboratory tests, imaging, and prescriptions) occurred at an average rate of 1.6 services per patient during the 24 months following nonindicated vitamin D testing. Some of these services were also classified as nonindicated. Conclusions: Evidence of a health service cascade following nonindicated vitamin D testing exists. Opportunities for improved consistency and quality of care related to vitamin D were observed in our health system. These results may inform clinical pathways related the prevention, evaluation, and treatment of low vitamin D.