BackgroundHigher continuity of GP care (CGPC), that is, consulting the same doctor consistently, can improve doctor–patient relationships and increase quality of care; however, its effects on patients with dementia are mostly unknown.AimTo estimate the associations between CGPC and potentially inappropriate prescribing (PIP), and with the incidence of adverse health outcomes (AHOs) in patients with dementia.Design and settingA retrospective cohort study with 1 year of follow-up anonymised medical records from 9324 patients with dementia, aged ≥65 years living in England in 2016.MethodCGPC measures include the Usual Provider of Care (UPC), Bice–Boxerman Continuity of Care (BB), and Sequential Continuity (SECON) indices. Regression models estimated associations with PIPs and survival analysis with incidence of AHOs during the follow-up adjusted for age, sex, deprivation level, 14 comorbidities, and frailty.ResultsThe highest quartile (HQ) of UPC (highest continuity) had 34.8% less risk of delirium (odds ratio [OR] 0.65, 95% confidence interval [CI] = 0.51 to 0.84), 57.9% less risk of incontinence (OR 0.42, 95% CI = 0.31 to 0.58), and 9.7% less risk of emergency admissions to hospital (OR 0.90, 95% CI = 0.82 to 0.99) compared with the lowest quartile. Polypharmacy and PIP were identified in 81.6% (n = 7612) and 75.4% (n = 7027) of patients, respectively. The HQ had fewer prescribed medications (HQ: mean 8.5, lowest quartile (LQ): mean 9.7, P<0.01) and had fewer PIPs (HQ: mean 2.1, LQ: mean 2.5, P<0.01), including fewer loop diuretics in patients with incontinence, drugs that can cause constipation, and benzodiazepines with high fall risk. The BB and SECON measures produced similar findings.ConclusionHigher CGPC for patients with dementia was associated with safer prescribing and lower rates of major adverse events. Increasing continuity of care for patients with dementia may help improve treatment and outcomes.