The continuity and regularity of primary care were associated with ambulatory care utilization: evidence from community healthcare centers in China

Abstract Background Continuity, acknowledged as one of the four core functions of primary care, has garnered extensive research attention; in contrast, the role of regularity has been less explored. Studies may omit the unique contributions of each by not considering them conjointly. More importantly, continuity and regularity might exert synergistic effects on health service utilization. This study extends the literature on the association between continuity of primary care and ambulatory care utilization by introducing regularity as an additional layer of primary care quality measurement, aiming to explain the association on healthcare utilization more accurately. Methods In this retrospective cohort study, we used secondary data extracted from electronic health records (EHR) of 10,122 patients with hypertension or diabetes in the T community healthcare center (CHC) in Shanghai, collected in 2017–2018. We measured continuity of care for patients and their general practitioners (GPs) using the Continuity of Care Index (COCI GP ,), Usual Provider of Care (UPC GP ), and Sequential Continuity of Care Index (SECON GP ), and produced an integrated continuity of care index (iCOC GP ) using principal component analysis (PCA). The modified regularity index (RI) was used to depict the regularity of care. Different models were selected to analyze the correlation between the continuity and regularity and the ambulatory care utilization. Results Three indicators were used to measure continuity of care, yielding median values of 0.47 (UPC GP ), 0.25 (COCI GP ), and 0.57 (SECON GP ). Regularity was measured using the RI, yielding median values of 0.29. The iCOC GP and the RI were not associated with the outpatient expenditure at general secondary and tertiary hospitals. For every 1% increase in RI, the probability of such visits increased by 1.1% (95% CI:0.3%-1.9%). Emergency department visits increased by 0.4% (95% CI: 0.2%-0.7%) for every 1% increase in iCOC GP but decreased by 0.6% (95% CI:0.1%-1.2%) for RI. Every 1% rise in iCOC GP was associated with a 2.9% (95% CI:2.5%-3.3%) increase in the probability of follow-up for chronic diseases, whereas it decreased by 1.4% (95% CI:0.6%-2.1%) for RI. Conclusion Continuity and regularity differentially affect the utilization of ambulatory care. Both continuity and regularity of care should be considered as key variables in future studies examining primary care and GP services.