Translation, cross-cultural adaptation, and validation of the Mouth Handicap in Systemic Sclerosis questionnaire (MHISS) into the Dutch language

The Mouth Handicap in Systemic Sclerosis (MHISS) is a French-generic questionnaire evaluating mouth-opening restriction, dryness, and esthetic concerns. The aim of this study was to translate and adapt the MHISS questionnaire into the Dutch language and evaluate its psychometric properties. The MHISS was translated according to international guidelines, field-tested among 16 systemic sclerosis (SSc) patients, and adapted. Subsequently, the Dutch MHISS was administered to 52 SSc patients visiting the outpatient or day patient clinic of a university hospital and readministered after 2 weeks. Internal consistency was tested by computing Cronbach's alpha. Test-retest reliability was determined by computing the intraclass correlation coefficient (ICC) and validity by determining associations with measures of overall functioning (Health Assessment Questionnaire (HAQ)), maximum mouth opening (MMO, in millimeter), subjective xerostomia (visual analog scale), and objective xerostomia (Saxon test). Patients had mean +/- standard deviation (SD) age and disease duration of 55 +/- 21 and 7.2 +/- 7.3 years. Twenty-seven (52 %) patients had diffuse cutaneous SSc. The mean Dutch MHISS score was 17.5 (SD 10.0) with Cronbach's alpha being 0.862. Dutch MHISS scores differed significantly between patients with high and low disability levels (HAQ, MMO, and subjective and objective xerostomia divided according to the median; paired t test). Spearman rank correlations with HAQ (r = 0.599, p = 0.000), MMO (r = -0.518, p = 0.000), and subjective xerostomia (r = 0.536, p = 0.000) were moderate; correlation with objective xerostomia did not reach statistical significance. The ICC was 0.94. The Dutch version of the MHISS demonstrated good psychometric properties and is useful in assessing mouth disability in SSc patients.