A questionnaire as an assessment tool is acceptable, easy, practical and feasible for analyzing PA in children and adolescents in a developing country like India. PA questionnaires help gather qualitative information about the type, location and circumstances of activity that the individual engages in [7]. Hence, we developed a PA questionnaire called the Madras Diabetes Research Foundation – Physical Activity Questionnaire for Children and Adolescents [MPAQ(c)], which would be acceptable and easy to use for surveillance studies on children and adolescents aged 10 to 17 years in a developing country like India. The objective of research reported in this paper was to evaluate the reliability and validity of this questionnaire against objectively collected accelerometer data.

Children and adolescents belonging to the age group of 10-17 years from Chennai, Tamil Nadu, India were recruited. Participants were selected from 74 areas across the 15 zones of urban and rural areas of Chennai. Heterogeneity of the sampling framework was maintained throughout the recruitment procedure by randomly recruiting participants from schools, and known households in the selected areas by door-to-door recruitment. A purposive sampling technique was used to select equal number of boys and girls across two age groups (10 to 14 and 15 to 17 years). For all participants, written informed consent from parents with the assent from the child were obtained before the start of the study. The Institutional Ethics Committee at Madras Diabetes Research Foundation approved the study protocol.

Anthropometric measurements and blood pressure were recorded using standard techniques. Height was measured using a stadiometer (SECA Model 213, Seca Gmbh Co, Hamburg, Germany) to the nearest 0.1cm. Weight was measured using a digital weighing scale (Tanita BC – 601, Tanita Corp., Japan) and recorded to the nearest 0.1 kg. Body mass index (BMI) was calculated as per standard formula. Waist circumference was measured in centimetres using a non-stretchable fiber measuring tape. Blood pressure and pulse was recorded in a rested sitting posi-tion in the right arm using a digital machine (Omron Corp., Tokyo, Japan) and rounded off to the nearest 2 mm Hg.

Madras Diabetes Research Foundation – Physical Activity Questionnaire for Children and Adolescents [MPAQ(c)]: This questionnaire has been developed from a PA questionnaire called the Madras Diabetes Research Foundation - Physical Activity Questionnaire [Adult version, MPAQ(a)], which was developed to assess PA levels in Asian Indian adults [9]. The questionnaire captures various dimensions of PA based on habitual and culturally relevant activities for upto a year.

The physical activity of children and adolescents can be generally divided into two main categories – school related activities and non-school related PA. The MPAQ(c) questionnaire was developed and validated in the English language. The questionnaire consists of 74 multiple choice questions presented in a ten-page survey form (Web Appendix I). Participants were asked to recall information about activities undertaken in the following domains: at school/college, transport, activities of daily living, leisure and vacation/holiday time activity. For each activity, the average amount of time spent on the activity and frequency (daily/week/month/year) were documented. Thus intensity, duration and frequency data were collected and weekday versus weekend analysis were made possible. The results from MPAQ(c) were tabulated based on the type of activity viz, sedentary and moderate-to-vigorous physical activity (MVPA).

Accelerometry: Participants had the accelerometer worn on a belt around their waist for five complete days (4 weekdays and 1 weekend) during waking hours; however, the device was allowed to be removed while bathing, swimming and sleeping. Moderate to vigorous physical activity was objectively assessed using the Actigraph (Actilife 5) GT3X+ Triaxial Accelerometer (Actigraph, Pensacola, Florida, USA) [10,11]. The device was worn on the hip of the dominant side (right in most cases). The accelerometers were initialized to monitor and record data in 60-second ‘epochs’ as ‘activity counts’ and sample frequency at 100 Hz. While initializing, each device was given a unique number denoting the individual participant with their age, gender, height, weight, date of birth and race. The GT3X+ device collects data from all three axis of movement regardless of the configuration, with Axis 1 collecting the vertical axis acceleration activity data, Axis 2 the horizontal axis data and Axis 3 the perpendicular axis data.

The baseline administration of MPAQ(c) was done between November and December, 2017. This was followed by a repeat administration after 2 weeks (average of 2-4 weeks) for upto a month later for assessing reliability.

For assessing relative validity, the MPAQ(c) was administered in a random order by trained researchers. The sample was chosen to get individuals across a wide age range, both genders and all categories of activity. The duration (minutes per day) spent in different intensity activities was calculated based on the coding scheme provided by Compendium of Physical Activities that describes the energy costs in terms of METs for various activities in children and adolescents aged 6 to 17.9 years [12,13]. The MPAQ(c) was administered anytime during the period the participant was wearing the accelerometer. Data from the MPAQ(c) was computed for a typical day, and then converted to minutes/day to make comparisons with the accelerometer data more realistic.

For content validity, the MPAQ(c) was evaluated by expert committee members at Madras Diabetes Research Foundation (MDRF). At first, the questions from MPAQ(a) were modified to suit the age group of children and adolescents. For instance, the work domain in adult questionnaire was replaced with school domain, and seasonal activity in adults was substituted with vacation for children and adolescents. Questions concerning sport activities in school and during weekends, lunch and snack break timings were found to be highly relevant. The experts evaluated the items in the questionnaire based on the content validity index (CVI), such that 1 was unsatisfactory and 4 was very satisfactory. The mean score of MPAQ(c) was 3.67 with a CVI of 0.92. The MPAQ (c) was considered to be suitable to be used by researchers to assess physical activity and sedentary behavior in the age group of 10 to 17 years.

Being an interviewer-administered questionnaire, inter-rater reliability was measured to assess the agreement between the interviewers. One interviewer administered the questionnaire to the participant while the other interviewer passively observed and rated participant’s response independently. This procedure was completed for a total of 30 participants by two interviewers who collected the questionnaires. A kappa value of 0.82 indicated good agreement among the interviewers.

Statistical analyses: Statistical analyses were performed using SAS (Statistical Analysis System) statistical package version 9.0 (SAS Institute Inc., Cary, NC). Shapiro-Wilks test was used to determine the normality of data. Mann-Whitney U test was used for those variables which deviated from normal distribution. Reliability of the MPAQ(c) was examined by calculating the intra-class correlation (ICC) of the activities reported by age and gender. ICC values of <0.40 were considered as poor agreement, 0.40-0.59 as fair, 0.60-0.74 as good and 0.75-1.00 as excellent agreement [14]. For assessing criterion validity, the MPAQ(c) was compared next to the triaxial accelerometer as a criterion. Spearman correlation coefficients and 95% CI were used for comparisons. Total duration (min/d) of time spent in sedentary and moderate-vigorous PA as estimated from the MPAQ(c) were compared against those recorded by the accelerometer using recognized cut-points [15]. As the accelerometer measured data was computed for an 8-hour valid day criterion, the data obtained from the MPAQ(c) was also calculated for a day so as to make it comparable. Bland and Altman plots were used to assess the agreement between data obtained using the MPAQ(c) and accelerometer (within the 95% limits). A P value <0.05 was considered as significant for all statistical measures.

A total of 110 participants responded to the MPAQ(c) on two occasions for the reliability study. Children and adolescents with incomplete MPAQ(c) data (n=2) or technical errors in the accelerometer instrument (n=4) were excluded from analysis. A final sample of 104 (53 between 10-14 y) participants were included in the study, of whom 43 and 61 participants completed the second round of questionnaire within 3 weeks and in the fourth week of the initial administration, respectively. Baseline characteristics of the participants are shown in Table I.

Table I Baseline Characteristics of the Study Participants (N=104)

The test re-test reliability of the questionnaire on study participants as per gender and age-group is shown in Table II. The maximum time was spent in the sleep domain followed by school and recreation domains. The agreement between first and second round of MPAQ(c) for boys (n=49) was 0.81 and for girls, was 0.74. The ICC was 0.81 in the age group of 15-17 years which was higher than 0.73 in the age group of 10-14 years. Overall, ICC of total MET minutes per week between the two rounds of MPAQ(c) was 0.77.

Table II Test-retest Reliability of Madras Diabetes Research Foundation Physical Activity Questionnaire [MPAQ(c)]

Correlation coefficients (95% CI) for sedentary behavior and moderate-vigorous PA for MPAQ(c) against the accelerometer were 0.52 (0.36, 0.64) and 0.41 (0.23, 0.55), respectively.

A good agreement [mean (SD) bias =-4.9 (96.1) min/d] between MPAQ(c) and accelerometer for sedentary behavior of older and younger children was present. For moderate-vigorous PA, good agreement was observed [mean (SD) bias = 0.01 (0.44) min/d].

Our study showed good reliability of MPAQ(c) in both genders across the age range of 10 to 17 years. MPAQ(c) showed moderate correlation against objective accelerometer measurement.

The values of internal consistency obtained in this study were higher compared to another study with similar characteristics done in the Netherlands [16]. The reliability of MPAQ(c) seen in this study is similar to that reported in a systematic analysis by Chinapaw, et al. [17]. The authors in this systematic analysis summarized and appraised 61 questionnaires from 54 studies for measuring PA in children, adolescents and youth. Their results showed that the most reliable PA questionnaire in children aged 8 to 10 years, the Girls Health Enrichment Multisite Study Activity Questionnaire had an ICC of 0.82 (0.75 for boys and 0.82 for girls).

Using the triaxial accelerometer as criterion, validity has been done in several studies. In a study conducted at Toronto, among girls aged 8-9 years, correlation between moderate-vigorous data collected using Habitual Activity Estimation Scale and accelerometer was shown to be 0.24 [18]. Validity correlations for total PA in children and adolescents with congenital heart disease aged 9 to 18 years was 0.51 indicating moderate correlation [19] which is similar to our finding in the normal population.

According to the MPAQ(c) data analyzed against the accelerometer reading, both boys and girls over-reported sedentary behavior and MVPA. This over-reporting was also reported with adult women in Southern India [20]. A systematic review of 83 studies, which evaluated PA in the pediatric population, found that about 72% of MVPAs evaluated using a questionnaire were over-reported by children and adolescents when compared to the accelerometer [21]. Such inaccuracies are one of the main limitations of the study. The reason for such inaccurate responses by children can be attributed to several social and psychological factors. Another limitation is that accelerometers can underestimate the intensity of effort associated with walking, running and cycling and in activities that require the device to be removed such as swimming and sleep [23]. As the data collection was interview-based, there were high possibilities of data variance between the different interviewers, which could be another limitation, even though in our experience with proper training and practice this error can be negated. Though the validated questionnaire could be used for assessment in any part of the country, it was tested only with one particular group of children and adolescents in only one large metropolitan city. The high compliance and completion rate by the participants is the main strength of the study. The ethnic-specific questionnaire used has information about the type and schedule of PA while the movement sensors in accelerometer provide information on the actual quantity of PA, which will permit a better understanding for the validation of subjective instruments [24,25].

The present study has shown that the MPAQ(c) for children and adolescents has good test-retest reliability among the 10-17 years age group. It is an instrument that can be used to assess the levels of PA in children and adolescents in low and middle-income countries like India due to its good psychometric properties.

Ethical clearance: Institutional ethics committee of Madras Diabetes Research foundation; No. IRB00002640, December, 2014.

Contributors: TSM: involved in conduct of the study, writing the first draft of manuscript and carrying out consecutive revisions; HR: co-ordinated the study, helped in data analysis and revisions of the manuscript; CA: analyzed the data and helped in data interpretation; NJ: collected the data and gave inputs to the manuscript; MP,VM: contributed to critical revisions for intellectual content of the manuscript; RMA: conceptualized the study, contributed inputs to data analysis and revisions of the manuscript.

Funding: None; Competing interest: None stated.

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