OBJECTIVES

: Although defining patients is importantly recognized as fastening the first button of the study, little is known about how to properly define the patients in health insurance (HI) claims data. This study aimed to compare prevalence and the economic burden according to the different approaches to define the patients focused on cardiovascular (CV) diseases in Korea.

METHODS

: A total of 388,492 patients diagnosed with a heart failure (HF) (I50, I11.0, I13.0, or I13.2) or a stroke (I60-I64) based on ICD-10 were defined as the study subjects from 2016 HI claims sample data. The base-case group was defined as patients with a CV disease (≥once) as a primary or secondary diagnosis. The conservative group was defined as patients with a CV disease (≥3 times) as a primary diagnosis order. The extended-definition patient group was defined as patients with a CV disease (≥once) regardless of a diagnosis order. Prevalence and the economic burden were compared in all patient-definition groups using multiple comparison methods.

RESULTS

: The prevalence of HF was estimated at 10.2 per 1,000 people in 2016, and 43.1% were male in the base-case group. The prevalence of HF has increased about eight-fold (2.9 to 22.5 per 1,000) and the annual average cost per patient of HF has increased twice ($1,020 to $1,929) as the definition of HF has expanded from being conservative. Meanwhile, the prevalence of stroke was 16.4 per 1,000 people and the variation of prevalence was lower (9.4 to 21.7 per 1,000) than HF. Contrary to the HF cost, the annual average cost of stroke in the conservative group was relatively high ($4,576) compared to the extended group ($3,507).

CONCLUSIONS

: This study’s findings suggested that defining patients in different approaches leads to substantially different outcomes in HF and stroke. Researchers who use claims data should be cautious to determine patient group.