Impact of mental illness on care for somatic comorbidities in France: a nation-wide hospital-based observational study.

People with a mental illness have a shorter lifespan and higher rates of somatic illnesses than the general population. They also face multiple barriers which interfere with access to healthcare. Our objective was to assess the effect of mental illness on the timeliness and optimality of access to healthcare for somatic reasons by comparing indicators reflecting the quality of prior somatic care in hospitalised patients. An observational nation-wide study was carried out using exhaustive national hospital discharge databases for the years 2009-2013. All adult inpatient stays for somatic reasons in acute care hospitals were included with the exception of obstetrics and day admissions. Admissions with coding errors were excluded. Patients with a mental illness were identified by their admissions for a psychiatric reason and/or contacts with psychiatric hospitals. The quality of prior somatic care was assessed using the number of admissions, admissions through the emergency room (ER), avoidable hospitalisations, high-severity hospitalisations, mean length of stay (LOS) and in-hospital death. Generalised linear models studied the factors associated with poor quality of primary care. A total of 17 620 770 patients were included, and 6.58% had been admitted at least once for a mental illness, corresponding to 8.96% of hospital admissions. Mentally ill patients were more often hospitalised (+41% compared with non-mentally patients) and for a longer LOS (+16%). They also had more high-severity hospitalisations (+77%), were more often admitted to the ER (+113%) and had more avoidable hospitalisations (+50%). After adjusting for other covariates, regression models found that suffering from a mental illness was significantly associated with a worse state for each indicator of the quality of care except in-hospital death. Inadequate primary care of mentally ill patients leads to more serious conditions upon admission to hospital and avoidable hospitalisations. It is, therefore, necessary to improve primary care and prevention for those patients.