ObjectivesAn ageing society includes high patient complexity. Various biopsychosocial problems result in a high burden for health-related professionals. The direct relationship between the burden and patient complexity, however, has not been reported. We aimed to examine correlations between the burden for the attending physicians and nurses, and Patient Centred Assessment Method (PCAM) scores of patient complexity.DesignProspective cohort study.SettingA regional secondary care hospital in Japan.ParticipantsWe included all inpatients admitted to our acute care unit between 1 July 2014 and 30 September 2014. Exclusion criteria were age <20 years, refusal to participate in the study and length of stay fixed at the time of admission.Main predictorPCAM total score in the initial phase of hospital admission.Main outcomeThe burden for each profession (measured on a Visual Analogue Scale).ResultsIn total, 201 inpatients participated [female/male=98/103, mean (SD) age of 77.4±11.9 years]. Spearman’s rank correlation coefficients between the burden and the PCAM score ranged from 0.23 to 0.32. All p values were <0.05. Multivariate analysis was conducted using multilevel mixed-effects linear regression to determine the association between the burden and the PCAM score in two models. Model 1 used the total PCAM score as the predictive variable. Model 2 used the PCAM factors, patient-oriented complexity and medicine-oriented complexity, as predictive variables. In Model 2, with the burden of physicians, medicine-oriented complexity was statistically significant, whereas with the burden of nurses, both age and patient-oriented complexity were statistically significant.ConclusionsPCAM scores correlated with the burden for physicians and nurses. Individual PCAM factors affected the burden for each profession differently.