The impact of diagnostic testing on therapeutic interventions.
OBJECTIVE
To gain insight into the usefulness of managing the earlier phase of decision making, we examined the relationship between selected diagnostic tests and the therapeutic interventions they might trigger.


METHODS
Medicare's National Claims History and Part B files were used to obtain summary information on 100% of all physician claims submitted from 1987 through 1993. We regressed the annual rates of selected therapeutic interventions on selected diagnostic tests, which had been previously paired based on the clinical expectation that the test might drive subsequent intervention.


METHODS
These data represent the physician services received by approximately 30 million elderly Americans in each of 7 years.


METHODS
Coefficient of determination (R2).


RESULTS
The annual rate for the diagnostic tests increased rapidly during the period (range, 1.4- to 3.0-fold increase) and accounted for the bulk of the variance in therapeutic intervention rates (R2>0.80, P<.01) for five diagnostic-therapeutic pairs: cardiac catheterization with cardiac revascularization procedures, imaging of the spine with back surgery, swallowing studies with percutaneous gastrostomy, mammography with breast biopsy and excision, and prostate biopsy with prostatectomy. Although the rate of abdominal ultrasound increased during the period, it was not related with either cholecystectomy or abdominal aortic aneurysm repair.


CONCLUSIONS
There has been a substantial increase in diagnostic testing in the United States that closely tracked the increase of clinically relevant downstream procedures. Managing diagnostic testing could be an important strategy for controlling the increase of therapeutic interventions.
Verrilli
D
D
Urban Institute, Washington, DC, USA.
Welch
H G
HG
D003955:Diagnostic Tests, Routine / Q000706:statistics & numerical data*; D016014:Linear Models; D016345:Medicare Part B / Q000706:statistics & numerical data; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D013812:Therapeutics / Q000706:statistics & numerical data*; D014481:United States; D014600:Utilization Review