Due to examinations, career events or industrial action by educators, 350 students were unavailable. Of the remaining 924 students, 65 declined to participate, so a total of 859 students were given the questionnaire to complete. Because some questions pertaining to the experience of playing problems were unanswered, 128 questionnaires were deemed incomplete. Therefore, 731 students (460 females) aged 7 to 17 years completed the questionnaire and survey appropriately. The school selection process ensured a representative range of instrument types, LY294002 concentration socioeconomic areas and age groups, as presented in Figure 1. Further details of the cohort are reported

elsewhere.18 All instrumental classes at the selected schools were sampled, with no exclusion criteria. Primary outcome: Respondents could indicate playing-related musculoskeletal symptoms (ie, the experience of mild aches and pains, experienced during and following playing, that may or may not affect performance). These were elicited by the question: ‘In the last month, did you feel any soreness anywhere when you played a musical instrument? Secondary outcome: Respondents could also indicate playing-related musculoskeletal disorders (ie, the experience of pain, weakness, lack of control, numbness, tingling

or other symptoms that interfered with the ability to play the instrument as usual). These were elicited by the question: ‘Did you feel MI-773 any instrument-playing-related soreness, tingling or weakness that stopped you from playing your instrument as well as

you usually Vasopressin Receptor play? The definitions that were used for disorders best determine rates of serious problems in adults.12 However, symptoms were chosen as the primary outcome because symptoms in children should be acknowledged early, so that the relevant risk factors can be identified and the appropriate intervention programs can be implemented to prevent development of disorders.13 A descriptive analysis was performed to characterise the non-music activities of the sample. To ensure adequate numbers for analysis, some categories of variables were combined, as presented in Table 1. A new variable – non-music-activity exposure – combined the frequency of participation and usual duration of participation, to establish categories of pattern of participation (eg, daily for 1 to 2 hours), and an exposure matrix27 assigned levels of exposure (low, moderate-low, moderate, high) for the patterns of non-music-activity participation, as presented in Table 2. Chi-square analysis was used to examine differences between males and females for categorical variables. ANOVA and bivariate Pearson correlation analysis examined the relationship between age and categorical variables. A series of logistic regression models were estimated with playing symptoms or playing disorders as the outcome variable.