Development of the quality‐of‐life questionnaires for use in Thailand: Translation and reliability test

Supornchai Kongpatanakul, Chulaluk Komoltri, Brian L. Strom

Research output: Contribution to journalArticle


In preparation for a clinical trial to be performed in Thailand, a study was undertaken to evaluate the reliability of a Thai version of the General Well‐Being Adjustment Scale (GWB) and Physical Symptoms Distress Index (PSDI) questionnaires previously used in an important US clinical trial of the effects of antihypertensive therapy on quality‐of‐life. Included were 46 consecutive patients with no major clinical complaints, attending general internal medicine clinic for regular follow‐up. Those who might have a significant alteration in their clinical course, e.g. change of medications, were not included. Thai version questionnaires were first translated, back‐translated, and assessed for cultural equivalence to the original version. Questionnaires were then completed by the patients twice, 7 days apart, and then a third time during the same day as the second administration. The item numbers on the third set of questionnaires were randomly reassigned to minimize patients' recall of their previous response. Internal consistency, intra‐day reliability, and inter‐day reliability of each subscale of GWB and the total PSDI questionnaires were analysed using the Cronbach's alpha and intra‐class correlation coefficients. Items in the General Health subscale of the GWB showed somewhat low internal consistency. However, for whole instruments, all parameters showed satisfactory results; the internal consistency of the whole GWB range from 0.90 to 0.93 for the three tests. Inter‐day and intra‐day reliability were 0.78 and 0.95, respectively. For the Thai version of PSDI questionnaires, internal consistencies were over 0.80 for all tests while inter‐day reliability was 0.78 and intra‐day reliability was 0.93. In conclusion, the Thai version of both questionnaires appeared to be reliable. Further study of the criterion validity of the questionnaires, however, is still needed before they can be used more broadly in Thailand.

Original languageEnglish (US)
Pages (from-to)343-349
Number of pages7
JournalPharmacoepidemiology and drug safety
Issue number6
StatePublished - Jan 1 1995

All Science Journal Classification (ASJC) codes

  • Epidemiology
  • Pharmacology (medical)


  • antihypertensive
  • clinical trial
  • cross‐cultural
  • health status questionnaire
  • quality‐of‐life
  • reliability
  • translation

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