Association between discharge planning department staffing levels and the average length of stay in acute care wards: a nationwide cross-sectional study in Japan

Objectives To investigate the association between staffing levels, particularly the number and combination of nurses and medical social workers (MSWs) in the discharge planning department, and the average length of stay (LOS) at the ward level in acute care hospitals in Japan.Design Cross-sectional study.Methods We used nationwide administrative hospital-level and ward-level data from fiscal year 2021, encompassing 4989 acute care wards in 923 hospitals across 216 secondary medical areas.Participants A total of 1036 wards in designated special function hospitals, 3398 general acute care wards with a 7:1 patient-to-nurse ratio (7:1 acute care wards) and 555 general acute care wards with a 10:1 patient-to-nurse ratio (10:1 acute care wards) were included in the analysis.Primary outcome measure Average LOS per ward.Methods Two-level multilevel linear regression models with random intercepts were stratified by ward type. The analysis was adjusted for ward-level, hospital-level and region-level covariates. We examined both the total staffing level (the total number of nurses and MSWs per 100 hospital beds) and the staffing combinations (high/low numbers of nurses and MSWs) in the discharge planning department.Results In multilevel models, no statistically significant associations were observed between discharge planning department staffing and ward-level average LOS across any ward type. In special function wards, wards with high nurse/low MSW staffing (coefficient: −1.07; 95% CI −2.39 to 0.25; p=0.11) and high nurse/high MSW staffing (coefficient: −1.16; 95% CI −2.45 to 0.13; p=0.08) tended to have shorter LOS than did those with low nurse/low MSW staffing. In 7:1 acute care wards, higher total staffing was not significantly associated with LOS (coefficient: −0.14; 95% CI −0.30 to 0.03; p=0.10). No clear associations were observed for 10:1 acute care wards.Conclusions This nationwide cross-sectional study found no statistically significant association between discharge planning department staffing levels and ward-level LOS in Japanese acute care hospitals. While LOS alone may not adequately capture the discharge planning relationship, the findings may inform staffing policies in healthcare systems facing population ageing.