Reliability and validity of adapted Turkish Version of Scoliosis Research Society-22 (SRS-22) questionnaire.

STUDY DESIGN

Outcome study to determine the internal consistency, and validity of adapted Turkish version of Scoliosis Research Society-22 (SRS-22) Instrument.

OBJECTIVES

To evaluate the validity and reliability of adapted Turkish Version of SRS-22 questionnaire.

SUMMARY OF BACKGROUND DATA

The SRS-22 questionnaire is a widely accepted questionnaire to assess the health-related quality of life for scoliotic patients in the United States. However, its adaptation in languages other than the source language is necessary for its multinational use.

METHODS

Translation/retranslation of the English version of the SRS-22 was done, and all steps for cross-cultural adaptation process were performed properly by an expert committee. Later, SRS-22 questionnaires and previously validated Short Form-36 (SF-36) outcome instruments were mailed to 82 patients who had been surgically treated for idiopathic scoliosis. All patients had a minimum of 2 years follow-up. Fifty-four patients (66%) responded to the first set of questionnaires. Forty-seven of the first time respondents returned their second survey. The average age of the 47 patients (12 male, 35 female) was 19.8 years (range, 14-31 years). The two measures of reliability as internal consistency and reproducibility were determined by Cronbach alpha statistics and intraclass correlation coefficient, respectively. Concurrent validity was measured by comparing with an already validated questionnaire (SF-36). Measurement was made using the Pearson correlation coefficient (r).

RESULTS

The study demonstrated satisfactory internal consistency with high Cronbach alpha values for the four of the corresponding domains (pain, 0.72; self-image, 0.80; mental health, 0.72; and satisfaction, 0.83). However, the Cronbach alpha value for function/activity domain (0.48) was considerably lower than the original questionnaire. The intraclass correlation coefficient for the same domains was 0.80, 0.82, 0.78, 0.81, and 0.76, respectively, demonstrating a satisfactory test/retest reproducibility. Considering concurrent validity, two domains had excellent correlation (r = 0.75-1), while 9 had good correlation (r = 0.50 to 0.75), and 6 had moderate correlation (r =0.25-0.50). Based on these results, question 18 in the function/activity domain with lower Cronbach alpha value was revised while question 15 was excluded. The revised SRS-22 was given to 30 adolescent idiopathic scoliosis patients not included in the index study. The revision could improve the Cronbach alpha value for function/activity domain from 0.48 to 0.81.

CONCLUSION

This study demonstrated that, if measures are to be used across cultures, the items must not only be translated well linguistically but also must be culturally adapted to maintain the content validity of the instrument at a conceptual level across different cultures. This may necessitate several validation studies to ensure and improve consistency in the content and face validity between source and target versions of a questionnaire due to difficulty in detecting subtle differences in the living habits of different cultures.