‘Missingness’ in health care: Associations between hospital utilization and missed appointments in general practice. A retrospective cohort study

Are multiple missed appointments in general practice associated with increased use of hospital services and missingness from hospital care? This novel study explores this in a population representative sample for the first time. A large, retrospective cohort (n = 824,374) of patient records from a nationally representative sample of GP practices, Scotland, 2013-2016. Requested data were extracted by a Trusted Third Party for the NHS, anonymised and linked to a unique patient ID, in the NHS Safehaven for analysis using established NHS Scotland linkage. We calculated the per-patient number of GP missed appointments from individual appointments and investigated the likelihood of hospital appointment or admission outcomes using a negative binomial model offset by number of GP appointments made. These models also controlled for age, sex, Scottish Index of Multiple Deprivation (SIMD) and number of long- term conditions (LTCs). Hospital attendance: Outpatient clinic attendances; hospital admissions; Emergency Department (ED) attendances. Hospital missingness: 'Did not attend' (DNAs) outpatient clinic appointments, 'irregular discharges' from admissions, and 'left before care completed' ED care episodes. Attendance: Patients in the high missed GP appointment (HMA) category were higher users of outpatient services (rate ratio (RR) 1.90, 95% confidence intervals (CI) 1.88-1.93) compared to those who missed none (NMA) with a much higher attendance risk at mental health services (RR 4.56, 95% CI 4.31-4.83). HMA patients were more likely to be admitted to hospital; general admissions (RR 1.67, 95% CI 1.65-1.68), maternity (RR 1.24, 95% CI 1.20-1.28) and mental health (RR 1.23, 95% CI 1.15-1.31), compared to NMA patients. Missing GP appointments was not associated with ED attendance; (RR 1.00, CI 0.99-1.01). The pattern of 'missingness' is consistent from primary care to hospital care: patients who have patterns of missing GP appointments have patterns of missing many outpatient appointments and are more likely to experience 'irregular discharge' from in-patient care. Missingness from outpatient mental health services is very high.