Identification of asthma cases in Japan using health insurance claims data: Positive and negative predictive values of proposed discrimination criteria: A single-center study.

BACKGROUND

Asthma cases have been increasingly investigated using claims data. However, the validity of defining asthma cases using health insurance claims in Japan is unclear. This study aims to assess the positive and negative predictive values of our proposed discrimination criteria for asthma.

METHODS

We developed discrimination criteria for asthma based on both the International Statistical Classification of Diseases and Related Health Problems (ICD)-10 disease codes for asthma and health insurance claims data for prescriptions and the treatment of asthma. Inclusion criteria were patients aged ≥16 years with at least one health insurance claim from April 2018 to March 2019 in all departments of our hospital. Physician-diagnosed asthma documented in the charts was used as the reference standard. Positive and negative predictive values of the discrimination criteria for physician-diagnosed asthma were estimated and compared with those estimated from discrimination criteria based solely on ICD-10 codes.

RESULTS

The new discrimination criteria had a high positive predictive value (PPV) of 86.0%, which was significantly higher than the PPV for the criteria defined solely by the ICD-10 codes (61.5%) (P < 0.01). The negative predictive values for both criteria were 100%. Allergic rhinitis and chronic cough were frequently misclassified as asthma using the discrimination criteria based solely on ICD-10 codes but were more likely to be appropriately classified using our proposed criteria.

CONCLUSIONS

Our proposed criteria adequately identified asthma subjects using health insurance claims data in Japan with a high PPV. Further studies are needed for external validation of these criteria.