Introduction: For the evaluation of the health status different questionnaires hasbeen used. The World Health Survey (WHS) Individual questionnaire has been applied in different countries as a short and standard tool. This questionnaire measures the health status of the individual in 9 domains. The objective of the current study was to validate the WHS Individual questionnaire in Farsi.

Methods: In this validation study, forward-backward translation procedure was applied to the questionnaire. The validity of the questionnaire was assessed by 10 content and methodology experts and some potential participants. Inter Rater Agreement (IRA), relevancy and clarity for each item as well as comprehensiveness
of the questionnaire were calculated. Reliability was measured using Cronbach`s alpha and Intra Class Correlation coefficient (ICC) through test-re-test in 20 convenient samples. To assess the discriminant validity, mean scores were compared between people with different self-rated health (SRH) status (good SRH=1743people and bad SRH=183). The means scores of the current questionnaire were also compared in two groups regarding the objective health (healthy=991, unhealthy=923).

Results: Total clarity, relevancy and comprehensiveness of the questionnaire were 91%, 94% and 90%, respectively. ICC ranged between 0.68 and 1 with the median of 0.89. Chronbach`s Alpha  was 0.76. The average scores in groups with good and bad self -rated health were 14.3±13.2 and 41.9±17.9, respectively (p<001).Average scores of the questionnaire were 24.2 ±16.8 and 10.2 ±11.5 in unhealthy and healthy groups based on the disease, respectively (p<001).

Conclusion: This study has provided some preliminary evidence on the reliability and validity of the Iranian version of the World Health Survey Individual Questionnaire. 

Keywords: Content validity, reliability, World Health Organization, health status, questionnaire development