OBJECTIVES: Patients can freely choose health care providers without referral under Taiwan’s National Health Insurance (NHI), therefore, hospital outpatient departments were crowded with patients whose chronic conditions can be treated in an primary care setting. Hypertension is the most common condition which can be treated in primary care setting but treated in hospitals instead. This study aimed at developing an algorithm for identifying patients with hypertension whose ambulatory care visits are treatable in primary care setting.

METHODS: Claim data from one million of randomly sampled beneficiaries enrolled in Taiwan’s NHI in 2010 was used to develop an algorithm of classifying ambulatory care visits made by patients with hypertension into various primary care groups. Each group had the same probability of visiting office-based physicians, similar comorbidities, and same level of previous health care utilization pattern such as hospitalization, the numbers of emergency department visits, the numbers of drugs prescribed and continuity of care. Classification and regression tree (CART) in SAS enterprise miner 13.1 was applied as the classification method.

RESULTS: There were 293,624 visits made by patients with essential hypertension. About 56% of these visits were treated in hospitals. 25 groups with various probability of getting care from primary care setting were constructed after classification tree analysis and the classification error rate was 35%. The most predictive factors to identify visits treatable in primary care setting were the absence of previous hospitalization, comorbidities, and the number of emergency visits in 6 months. The proportion of patients with hypertension treatable in primary care setting among hospitals ranged from 44% to 63%.

CONCLUSIONS: A large proportion of patients with hypertension treated in hospitals had similar conditions as those who were treated in primary care settings. A health policy to redirect these patients into primary care settings is warranted to improve the efficiency and equity.