Measures of frequency used in cohorts studies to evaluate the suicidal behaviour in young people (12-26 years): A systematic review.

INTRODUCTION: A priority for the WHO by 2020 is to have reduced the rates of suicide; they indicate difficulties in giving precise estimations due to a wide variety of factors, which include aspects related to the statistical measurements themselves of suicidal behaviour. The proportion of deaths from suicide is 8.5% among young people between 15-29 years of age.

OBJECTIVE: To review the methodology used to express the frequency of suicidal behaviour in young people and to describe the methodological characteristics of the studies reviewed.

METHOD: A systematic review of longitudinal studies registered on PROSPERO. The extracted information included the following: year of publication, journal, population size, sample, country, design, age, percentage of men, follow-up time and losses, suicidal behaviour, risk factors, ethical aspects, fundamentally, evaluating the measures of frequency used.

RESULTS: Eighty-two articles were selected from 37,793 documents. None of the studies define the measure of frequency used for suicidal behaviour, there are currently up to 9 different ways of measuring it. The populations are students or the general population (66%), birth cohorts (16%) and specific groups. Follow-up was from 24 weeks to 30 years. Only 24.1% of the studies took ethical aspects into consideration.

CONCLUSIONS: Researchers must make an effort to reach an agreement on the measures of frequency used in suicidal behaviour studies, as the methodological and terminological variability currently used impedes making any comparisons between different studies or understanding the real dimension of the problem.