Maximum Phonation Time Normative Values Among Malaysians and Its Relation to Body Mass Index

Summary Objective Maximum phonation time (MPT) is a test to measure glottic efficiency for laryngeal pathology screening and treatment monitoring. The normative value of MPT for South East Asia population has yet to be reported. It is postulated that MPT may be affected by body mass index (BMI) despite the paucity of evidence. Therefore, this study was designed to establish the normative value of MPT for a South East Asia population and investigate its relation to BMI. Design & Setting This cross-sectional study was conducted in Universiti Kebangsaan Malaysia Medical Center between May and September 2017. Participants and Methods Three hundred males and females with mean age of 30.23 (±11.04) years were recruited in equal number for each gender (n = 150) and divided into 3 groups of 50 according to their BMI (n = 50). The three groups are non-obese (BMI≤22.9kg/m2); obese (BMI between 23 and 34.9 kg/m2); and morbidly obese (BMI >35kg/m2). BMI and Voice Handicap Index-10 (VHI-10) were obtained. The average of three readings of MPT was measured using a stopwatch while the participants phonate /a/, /i/ and /u/. Unpaired t-test and ANOVA were used to compare means between and across groups. Spearman correlation assessed the correlation between MPT and BMI. Main outcome measures The normative values of MPT of both genders and correlation with BMI were analyzed. Results The MPT normative values for males and females in the non-obese group were of 21.41 (±6.85) seconds and 18.05 (±5.06)seconds respectively for /a/. The MPT for all vowels were significantly higher in males across the BMI groups (P ≤ 0.05). There was low negative correlation between MPT and BMI in both genders. Conclusions This pioneering study documented the normative values of MPT among Malaysians showed that males had longer MPT than females across the BMI groups. Obesity affects the MPT in that as BMI increases, the MPT decreases.