Validating diagnoses from hospital discharge registers change risk estimates for acute coronary syndrome

Objectives

Hospital discharge registers are cost-efficient data sources; however, their usability is highly dependent on the quality of the registered data. No previous studies have examined the effect of validating discharge diagnoses on relative risk estimates.

We examined if a validation of acute coronary syndrome (ACS) diagnoses identified in a hospital discharge register changed the relative risk estimates of well-established risk factors for ACS.

Methods

All first-time ACS diagnoses (n=1138) in the Danish National Patient Registry were identified among male participants in the Danish cohort study "Diet, Cancer and Health" (n=26 946). Medical records were retrieved and reviewed using current European Society of Cardiology criteria for ACS. The ACS diagnosis was confirmed in a total of 781 participants.

Results

The relative risk estimates of ACS for a range of well-established cardiovascular risk factors appeared higher when using validated compared to crude hospital discharge data:

smoking: 2.47 (2.13 - 2.87) vs. 2.06 (1.83 - 2.31),

hypertension:  1.77 (1.57 - 1.98) vs. 1.74 (1.58 - 1.91),

hypercholesterolemia: 1.74 (1.42 - 2.14) vs. 1.68 (1.43 - 1.90)

diabetes mellitus: 1.57 (1.30 - 1.90) vs. 1.39 (1.18 - 1.64), respectively.

Conclusions

Use of hospital discharge diagnoses of ACS leads to underestimation of the impact of well established risk factors for ACS, compared to use of validated diagnoses.

Funding

The study was supported by MD Kopps Foundation, The Research Foundation of the Danish Medical Association in North Jutland and the Danish Heart Foundation.