Abstract
Background
A recent systematic review recommended time-varying methods for minimizing bias when estimating the excess length of stay (LOS) for healthcare-associated infections (HAIs); however, little evidence exists concerning which time-varying method is best used for HAI incidence studies.
Aim
To undertake a retrospective analysis of data from a one-year prospective incidence study of HAIs, in one teaching hospital and one general hospital in NHS Scotland.
Methods
Three time-varying methods – multistate model, multivariable adjusted survival regression, and matched case–control approach – were applied to the data to estimate excess LOS and compared.
Findings
The unadjusted excess LOS estimated from the multistate model was 7.8 (95% confidence interval: 5.7–9.9) days, being shorter than the excess LOS estimated from survival regression adjusting for the admission characteristics (9.9; 8.4–11.7) days, and the adjusted estimates from matched case–control approach (10; 8.5–11.5) days. All estimates from the time-varying methods were much lower than the crude time-fixed estimates of 27 days.
Conclusion
Studies examining LOS associated with HAI should consider a design which addresses time-dependent bias as a minimum. If there is an imbalance in patient characteristics between the HAI and non-HAI groups, then adjustment for patient characteristics is also important, where survival regression with time-dependent covariates is likely to provide the most flexible approach. Matched design is more likely to result in data loss, whereas a multistate model is limited by the challenge in adjusting for covariates. These findings have important implications for future cost-effectiveness studies of infection prevention and control programmes.
A recent systematic review recommended time-varying methods for minimizing bias when estimating the excess length of stay (LOS) for healthcare-associated infections (HAIs); however, little evidence exists concerning which time-varying method is best used for HAI incidence studies.
Aim
To undertake a retrospective analysis of data from a one-year prospective incidence study of HAIs, in one teaching hospital and one general hospital in NHS Scotland.
Methods
Three time-varying methods – multistate model, multivariable adjusted survival regression, and matched case–control approach – were applied to the data to estimate excess LOS and compared.
Findings
The unadjusted excess LOS estimated from the multistate model was 7.8 (95% confidence interval: 5.7–9.9) days, being shorter than the excess LOS estimated from survival regression adjusting for the admission characteristics (9.9; 8.4–11.7) days, and the adjusted estimates from matched case–control approach (10; 8.5–11.5) days. All estimates from the time-varying methods were much lower than the crude time-fixed estimates of 27 days.
Conclusion
Studies examining LOS associated with HAI should consider a design which addresses time-dependent bias as a minimum. If there is an imbalance in patient characteristics between the HAI and non-HAI groups, then adjustment for patient characteristics is also important, where survival regression with time-dependent covariates is likely to provide the most flexible approach. Matched design is more likely to result in data loss, whereas a multistate model is limited by the challenge in adjusting for covariates. These findings have important implications for future cost-effectiveness studies of infection prevention and control programmes.
Original language | English |
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Pages (from-to) | 44-51 |
Number of pages | 8 |
Journal | Journal of Hospital Infection |
Volume | 126 |
Early online date | 2 Jun 2022 |
DOIs | |
Publication status | Published - Aug 2022 |
Keywords
- healthcare-associated infections
- excess length of stay
- time-varying approaches
ASJC Scopus subject areas
- Microbiology (medical)
- Infectious Diseases