Erkki Kronholm1, Pekka Jousilahti2, Tiina Laatikainen2, Tea Lallukka3, Markku Peltonen2, Johanna Seppänen2, Lauri Virta4. 1. National Institute for Health and Welfare, Helsinki, Finland; Finnish Institute of Occupational Health, Turku, Finland. Electronic address: erkki.kronholm@ttl.fi. 2. National Institute for Health and Welfare, Helsinki, Finland. 3. Finnish Institute of Occupational Health, Helsinki, Finland; Department of Public Health, University of Helsinki, Finland. 4. The Social Insurance Institution, Turku, Finland.
Abstract
PURPOSE: Whether the association between hypnotic and increased mortality risk is created by causation or confounding, has been long debated. We further examined the possibility of confounding by indication with a comprehensive approach. METHODS: The National FINRISK Study cohorts of 1997, 2002, and 2007 (25,436 participants aged 25-74) were followed up until July 2012. There were 1822 deaths, and at least one gender, baseline age and cohort matched 'control' was found for 1728 'cases' yielding a final analytical sample of 3955 individuals. An index age, equivalent to the age at death of their respective cases' was set for each control. Hypnotic drug purchases were followed from the Finnish nationwide register during a 36-month run-up period before the date of death/index date. The prevalence and incidence of hypnotic purchases were compared between cases and matched controls. Moreover, latent developmental trajectories of purchases were modelled and their relations with specific and all-cause death risks were analysed. RESULTS: An increasing difference between cases and controls was observed as regards the use of hypnotic drugs. During the last 30 months before the date of death/index date, the rate ratio of incident purchases between cases and controls was 2.37 (95% CL, 1.79-3.12) among older and 3.61 (95% CL, 2.37-5.89) among younger individuals. The developmental trajectories of hypnotic drug purchases were differently and by interpretation plausibly associated with specific mortality risks. CONCLUSIONS: In most cases the association between hypnotics and mortality risk is created by symptomatic treatment when death is approaching.
PURPOSE: Whether the association between hypnotic and increased mortality risk is created by causation or confounding, has been long debated. We further examined the possibility of confounding by indication with a comprehensive approach. METHODS: The National FINRISK Study cohorts of 1997, 2002, and 2007 (25,436 participants aged 25-74) were followed up until July 2012. There were 1822 deaths, and at least one gender, baseline age and cohort matched 'control' was found for 1728 'cases' yielding a final analytical sample of 3955 individuals. An index age, equivalent to the age at death of their respective cases' was set for each control. Hypnotic drug purchases were followed from the Finnish nationwide register during a 36-month run-up period before the date of death/index date. The prevalence and incidence of hypnotic purchases were compared between cases and matched controls. Moreover, latent developmental trajectories of purchases were modelled and their relations with specific and all-cause death risks were analysed. RESULTS: An increasing difference between cases and controls was observed as regards the use of hypnotic drugs. During the last 30 months before the date of death/index date, the rate ratio of incident purchases between cases and controls was 2.37 (95% CL, 1.79-3.12) among older and 3.61 (95% CL, 2.37-5.89) among younger individuals. The developmental trajectories of hypnotic drug purchases were differently and by interpretation plausibly associated with specific mortality risks. CONCLUSIONS: In most cases the association between hypnotics and mortality risk is created by symptomatic treatment when death is approaching.