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Changes in statistical methods affected the validity of official suicide rates
Finn Gjertsen1, Lars Age Johansson
1Department of Suicide Research and Prevention, Norwegian Institute of Public Health, Nydalen, NO-Oslo, Norway. finn.gjertsen@fhi.no
Journal of Clinical Epidemiology
|April 12, 2011
Summary
Official suicide rates in Norway decreased significantly from 1988-1994, reflecting a real change. However, declining data quality since the late 1990s complicates accurate assessment of suicide trends.
Area of Science:
- Public Health
- Epidemiology
- Mortality Statistics
Background:
- Official suicide rates are crucial for public health surveillance.
- Changes in registration and coding practices can impact the accuracy of mortality statistics.
- Understanding these influences is vital for reliable trend analysis.
Purpose of the Study:
- To investigate the influence of registration and coding changes on Norwegian suicide rates between 1988 and 2002.
- To assess the reliability of official suicide statistics over time.
Main Methods:
- Utilized Poisson regression to analyze suicide rates and competing causes of death in Norway.
- Examined mortality data from 1988 to 2002.
Main Results:
- Suicide mortality significantly decreased by 23.7% from 1988 to 1994.
- Rates of causes potentially masking suicide remained stable or decreased during 1988-1994.
- From 1994 to 2002, suicide rates showed no significant change, while accidental poisoning (a potential mask for suicide) increased by 32.4%.
- "Ill-defined causes" of death increased by 16.7%, indicating declining data quality.
Conclusions:
- The 1988-1994 decrease in Norwegian suicide rates appears to be a genuine trend.
- Deterioration in mortality statistics quality since the late 1990s hinders accurate assessment of recent suicide trends.
- Inconsistent data quality, indicated by "ill-defined" causes, complicates international suicide rate comparisons.
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