Measuring the impact of step down intermediate care on delayed discharge: an interrupted time series analysis

Background Intermediate care (IC) acts as a bridging service between hospital and home, for those deemed medically fit for discharge but who are delayed in hospital. The aim of this study was to measure the effect of IC and a 72-hour discharge target on days delayed. Methods Rate of days delayed per 1000 population aged 75 years+ in Glasgow City was compared before and after onset of IC with a 6-month phase-in period, using segmented linear regression. Inverclyde and West Dunbartonshire (IWD) was a control. Autoregressive and moving average terms were included in the model, as well as a Fourier term to adjust for seasonality. Results Prior to IC, rate of days delayed increased in both Glasgow City and the rest of Scotland. There was a large reduction in rate of days delayed in Glasgow during the phase-in period, greater than the rest of Scotland but comparable with that observed in IWD, with subsequent increases thereafter. Adjusting for changes in IWD, the impact of IC and the discharge target in Glasgow City was a level change of -15.20 (95% CI -17.52 to -12.88) and a trend change of -0.29 (95% CI -0.55 to -0.02). This is equivalent to a predicted reduction due to IC of -16.04 days delayed per 1000 population per month, in June 2016, and a relative reduction of 35%. Conclusion IC and the 72-hour discharge target were associated with a reduction in days delayed. Rate of days delayed continued to increase over time, although at a slower rate than if IC had not been implemented.