Shift characteristics | IRR* | 95% CI |

Delayed vital signs observations | ||

Proportion of RN-HPPD deriving from ≥12-hour shifts | 0.96 | 0.91 to 1.01 |

Proportion of HCA-HPPD deriving from ≥12-hour shifts | 1.05† | 1.00 to 1.10‡ |

Missed vital signs observations | ||

Proportion of RN-HPPD deriving from ≥12-hour shifts | 0.96 | 0.91 to 1.01 |

Proportion of HCA-HPPD deriving from ≥12-hour shifts | 1.04 | 0.99 to 1.09 |

Random effect: ward.

*Incidence rate ratio (all models include random effect for ward and RN-HPPD/HCA-HPPD).

†Statistically significant at p<0.05.

‡The lower bound 95% CI for proportion of HCA-HPPD deriving from ≥12-hour shifts is 1.0004, and it has been rounded to 1.00 for reporting purposes.

HCA-HPPD, healthcare assistant hours per patient day; RN-HPPD, registered nurse hours per patient day.