Yield of laboratory tests for case-finding in the ambulatory general medical examination.
Level 3 - non-randomized controlled study
Prospective cohort study of diagnostic and therapeutic yield
PubMed 8757353 · doi:10.1016/s0002-9343(96)80068-4
What was done
A prospective cohort study evaluated 531 patients (mean age 63 ± 14 years; 57% female) across four Mayo Clinic general internal medicine divisions. Investigators evaluated 1,508 laboratory tests (comprising 7,008 individual components) ordered for case-finding during comprehensive ambulatory medical examinations, measuring the diagnostic yield (new diagnoses) and therapeutic yield (new therapies) of complete blood counts, chemistry panels, lipid profiles, thyroid tests, and urinalysis.
What was found
Of 1,508 case-finding tests, 36% (544/1,508) were abnormal; 6% (33/544) were repeated and 9% (47/544) led to further investigations. The overall diagnostic yield was 4.8% (73 new diagnoses) and therapeutic yield was 4.0% (60 new therapies). Therapeutic yield by test type was: lipid profile (16.5%), chemistry panel (2.8%), complete blood count (0.9%), urinalysis (0.8%), and thyroid tests (0.7%). Therapeutic yield was approximately twice as high in new versus established patients, with no association observed for age, gender, or referral distance.
Why it matters
Routine broad laboratory screening during ambulatory general exams offers minimal therapeutic return, indicating that case-finding efforts in this setting are primarily justified for lipid profiles rather than panels like complete blood counts, urinalysis, chemistry, or thyroid screens.
Limits
The study was conducted within a single academic health system (Mayo Clinic). Long-term clinical outcomes, direct and indirect costs, and potential harms resulting from further investigations of abnormal results were not assessed in the abstract.
Cited by
- contradicts The most common blood tests requested by a physician during a standard physical exam are a complete blood count (CBC), a metabolic panel, and an insulin test.