Association Between Health System Factors and Utilization of Routine Laboratory Tests in Clinical Teaching Units: a Cohort Analysis.

Abstract

Few studies have looked at health system factors associated with laboratory test use. To determine the association between health system factors and routine laboratory test use in medical inpatients. We conducted a retrospective cohort study on adult patients admitted to clinical teaching units over a 3-year period (January 2015 to December 2017) at three tertiary care hospitals in Calgary, Alberta. Patients were assigned to a Case Mix Group+ (CMG+) category based on their clinical characteristics, and patients in the top 10 CMG+ groups were included in the cohort. The examined health system factors were (1) number of primary attending physicians seen by a patient, (2) number of attending medical teams seen by a patient, (3) structure of the medical team, and (4) day of the week. The primary outcome was the total number of routine laboratory tests ordered on a patient during their admission. Statistical models were adjusted for age, sex, length of stay, Charlson comorbidity index, and CMG+ group. The final cohort consisting of 36,667 patient-days in hospital (mean (SD) age 62.5 (18.4) years) represented 5071 unique hospitalizations and 4324 unique patients. Routine laboratory test use was increased when patients saw multiple attending physicians; with an adjusted incidence rate ratio (IRR) of 1.46 (95% CI, 1.37-1.55) for two attending physicians, and 2.50 (95% CI, 2.23-2.79) for three or more attending physicians compared to a single attending physician. The number of routine laboratory tests was slightly lower on weekends (IRR 0.98, 95% CI, 0.96-0.99) and on teams without a senior resident as part of their team structure (IRR 0.89, 95% CI 0.830.96). The associations observed in this study suggest that breaks in continuity of care, including increased frequency in patient transfer of care, may impact the utilization of routine laboratory tests.