The Italian version of the Mouth Handicap in Systemic Sclerosis scale (MHISS) is valid, reliable and useful in assessing oral health-related quality of life (OHRQoL) in systemic sclerosis (SSc) patients

In systemic sclerosis (SSc), mouth and face involvement leads to problems in oral health-related quality of life (OHRQoL). Mouth Handicap in Systemic Sclerosis scale (MHISS) is a 12-item questionnaire specifically quantifying mouth disability in SSc, organized in 3 subscales. Our aim was to validate Italian version of MHISS, by assessing its test-retest reliability and internal and external consistency in Italian SSc patients. Forty SSc patients (7 dSSc, 33 lSSc; age and disease duration: 57.27 +/- A 11.41, 9.4 +/- A 4.4 years; 22 with sicca syndrome) were evaluated with MHISS. MHISS was translated following a forward-backward translation procedure, with independent translations and counter-translation. Test-retest reliability was evaluated, comparing the results of two administrations, with intraclass correlation coefficient (ICC). Internal consistency was assessed by Cronbach's alpha and external consistency by comparison with mouth opening. MHISS has a good test-retest reliability (ICC: 0.93) and internal consistency (Cronbach's alpha:0.99). A good external consistency was confirmed by correlation with mouth opening (rho: -0,3869, p: 0.0137). Total MHISS score was 17.65 +/- A 5.20, with scores of subscale 1 (reduced mouth opening) of 6.60 +/- A 2.85 and scores of subscales 2 (sicca syndrome) and 3 (aesthetic concerns) of 7.82 +/- A 2.59 and 3.22 +/- A 1.14. Total and subscale 2 scores are higher in dSSc than in lSSc. This result may be due to the higher presence of sicca syndrome in dSSc than in lSSc (p = 0.0109). Our results support validity and reliability in Italian SSc patients of MHISS, specifically measuring SSc OHRQoL.