Statistic* | North London Eye Study cohort | Population of England and Wales |
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*Calculations: | ||

a, observed number of deaths/total person years at risk = (222/5210.1). | ||

b, for NLES, derived from a using exp(−0.0427 × 1.0) × 10^{3}. | ||

For population, derived from Office for National Statistics 1996 mortality statistics. | ||

c, calculated by direct standardisation, using the study cohort sex and age specific cumulative incidence rates, and the population sex-age structure as the standard. | ||

f, For population, taken from Office for National Statistics 1996 mortality statistics. | ||

g, calculated by applying the population sex and age specific death rates (Pi) to the study cohort. | ||

k, variance of the SMR taken as 10^{4} × ΣniPiQi/(ΣniPi)^{2} as outlined by Armitage,^{12} when the purpose is to see whether the SMR differs significantly from 100% (ni is the number in sex-age group i in the study cohort, and Qi=1−Pi). | ||

a Death rate per 1000 PYAR | 42.6 | |

b 1 year cumulative incidence (per 1000) | 41.7 | 56.3 |

c Standardised cumulative incidence | 42.1 | |

d Number of people aged 65 and older | 1502 | 8258800 |

e Total PYAR | 5210.1 | |

f Observed number of deaths | 222 | 465102 |

g Expected deaths if population rates applied | 281.3 | |

h Standardised mortality ratio: f/g (%) | 78.9 | |

k 95% confidence limits for SMR | 67.8 to 90.1 |