Background: Though critical to primary care, continuity of care has rarely been examined in China. This study aims to assess the relationship between continuity of care and healthcare costs among patients with chronic diseases within primary care settings in China.

Methods: In this cross-sectional study, we used a social health insurance claims dataset of 1406 patients with hypertension and/or diabetes in Yuhuan City, Zhejiang Province collected in 2017-2019. We measured continuity of care using the Bice-Boxerman Continuity of Care (COC) Index, Herfindahl Index (HI), Sequential Continuity of Care (SECON) Index, Usual Provider of Care (UPC), and a binary variable indicating whether a patient's UPC was a primary care provider. We examined the associations between continuity of care and healthcare costs in the same period and the subsequent year, using ordinary least squares regression for the outpatient costs and two-part regression for the inpatient costs. Based on the regression coefficients, we predicted costs saved if each continuity measure was set to 1 from the status quo.

Results: When optimum continuity were to be achieved, 7.12-27.29% of total outpatient costs and 55.38-73.35% of total inpatient costs could be saved compared to the status quo during the two-year study period. If optimum continuity were to be achieved in the first year, 7.47%-21.78% of total outpatient costs and 8.84-40.22% of total inpatient costs could be saved in the second-year.

Conclusions: Care continuity indicators were consistently associated with reduced outpatient costs and hospitalization risks. Future health reform in China should further enhance continuity of care in primary care.