The purpose of the study was to investigate the effect of mouth-opening exercise training with follow-up telephone calls for preventing postoperative trismus in patients with oral cancer. The specific aims were to test the intervention effects on enhancing mouth-opening exercise practice, MIO, and mandibular function. We hypothesized that the intervention group would show 1) better adherence to mouth-opening exercises, 2) greater MIO, and 3) better mandibular function over time, compared to the control group.
The study is a quasi-experimental design with repeated measures. A convenience sample of 44 oral cancer patients was recruited to control group the 38 patients was recruited to the intervention group Subjects in the control group received routine care including written mouth exercise instructions. Subjects in both groups received two 30-minute individual trainings on the mouth-opening exercises before discharge from the hospital. Patients in the experimental group were provided with two one-on-one oral exercise instruction courses after receiving the last two radiation treatments by nurse practitioner. Subjects in the intervention group received additional 2 follow-up phone calls from the interventionist to enhance mouth-opening exercise adherence. Data on MIO and mandibular function impairment were collected before surgery, at one-month, three-months and six month after radiotherapy, using the TheraBite Range-of-Motion scale and the Mandibular Function Impairment Questionnaire. The study was approved by the research ethics committee of the hospital where the data were collected.
All statistical analyses were carried out using the SPSS statistical package version 20.0 (SPSS Inc., Chicago, IL, USA). Characteristics of the subjects were summarized by percentages, means, and standard deviations (SDs). Chi-squared tests or Fisher's exact tests and two independent samples t-tests were used to examine group baseline equivalency. Value changes of study outcomes (MIO and mandibular function impairment) and mouth-opening exercises performed from T1, T2, to T3 were expressed in two study groups. A general linear model was used to model these outcomes as a function of main group effect and main time effect. An interaction term (group difference by time) was added into each model to investigate the synergistic effect of the intervention with time. Both the stability analysis and the analysis of repeated relationships were performed by generalized estimation equations (GEE).