Trends and Between-Physician Variation in Laboratory Testing: A Retrospective Longitudinal Study in General Practice

Area of Science:

• Primary care
• Clinical pathology
• Health services research

Background:

• General practitioners (GPs) frequently order laboratory tests, but trends and variations in their utilization are not well understood.
• Understanding these patterns is crucial for optimizing healthcare resource allocation and ensuring consistent medical practice.

Purpose of the Study:

• To analyze time trends and between-GP variation in the utilization of 15 common laboratory tests ordered by Swiss GPs from 2009 to 2018.
• To identify specific laboratory tests with significant temporal increases and high inter-physician variability.

Main Methods:

• Retrospective longitudinal study analyzing over six million GP consultations in Switzerland (2009-2018).
• Calculation of specific laboratory testing rates (sLTR) for 15 test types.
• Mixed-effect logistic regression for age- and sex-adjusted trend analysis, accounting for patient clustering within GPs.
• Quantification of between-GP variation using intraclass correlation coefficients (ICC).

Main Results:

• Nine of the 15 analyzed laboratory tests showed significant temporal increases over the decade.
• Most prominent increases were observed for vitamin D (OR 1.88) and glycated hemoglobin (OR 1.87).
• Vitamin D, glycated hemoglobin, C-reactive protein, and vitamin B12 exhibited both substantial increases in use and high between-GP variation (ICC ranging from 0.075 to 0.202).

Conclusions:

• Laboratory test ordering by GPs has increased significantly, with notable rises in vitamin D and glycated hemoglobin testing.
• Substantial variation in the use of certain tests among GPs indicates potential inconsistencies in medical practice.
• Findings suggest a need for further investigation into the drivers of increased testing frequency and inter-physician variability to address potential overuse.