The Association of Cold Ambient Temperature With Fracture Risk and Mortality: National Data From Norway - A Norwegian Epidemiologic Osteoporosis Studies (NOREPOS) Study

Abstract

Norway is an elongated country with large variations in climate and duration of winter season. It is also a high-risk country for osteoporotic fractures, in particular hip fractures, which cause high mortality. Although most hip fractures occur indoors, there is a higher incidence of both forearm and hip fractures during wintertime, compared with summertime. In a nationwide longitudinal cohort study, we investigated whether cold ambient (outdoor) temperatures could be an underlying cause of this high incidence and mortality. Hospitalized/outpatient forearm fractures (ICD-10 code S52) and hospitalized hip fractures (ICD-10 codes S72.0-S72.2) from 2008-2018 were retrieved from the Norwegian Patient Registry. Average monthly ambient temperatures (degrees Celsius, °C) from the years 2008-2018 were provided by the Norwegian Meteorological Institute and linked to the residential area of each inhabitant. Poisson models were fitted to estimate the association (Incidence Rate Ratios (IRR), 95% Confidence Intervals (CI)) between temperature and monthly incidence of total number of forearm and hip fractures. Flexible parametric survival models (Hazard ratios (HR), 95% CI) were used to estimate the association between temperature and post hip fracture mortality, taking the population mortality into account. Monthly temperature ranged from -20.2°C to 22.0°C, with a median of -2.0°C in winter and 14.4°C in summer. At low temperatures (

The Association of Cold Ambient Temperature With Fracture Risk and Mortality: National Data From Norway - A Norwegian Epidemiologic Osteoporosis Studies (NOREPOS) Study