Changes in body mass index and health related quality of life from childhood to adolescence

Objective . To determine longitudinal relationships between body mass index (BMI) and health-related quality of life (HRQoL) in an adolescent population sample.
Design. Data collected in 2000 and 2005 within the Health of Young Victorians longitudinal cohort study.
Setting. Originally a community sample of elementary school students in Victoria, Australia. Follow-up occurred in either secondary schools or individuals homes.
Participants. Cohort recruited in 1997 via a random sampling design from Victorian elementary schools. Originally comprising 1 943 children, 1 569 (80.8%) participated in 2000 (wave 2, 8 – 13 years) and 851 (54%) in 2005 (wave 3, 13 – 19 years).
Main outcome measures. In both waves participants and their parents completed the PedsQL, a 23-item child HRQoL measure, and BMI z-scores and status (non-overweight, overweight or obese) were calculated from measured height and weight. Associations were tested cross-sectionally and longitudinally (linear regression, adjusted for baseline values)
Results. A total of 81.6% remained in the same BMI category, while 11.4% and 7.0% moved to higher and lower categories, respectively. Cross-sectional inverse associations between lower PedsQL and higher BMI categories were similar to those for elementary school children. Wave 2 BMI strongly predicted wave 3 BMI and wave 2 PedsQL strongly predicted wave 3 PedsQL. Only parent-reported Total PedsQL score predicted higher subsequent BMI, though this effect was small. Wave 2 BMI did not predict wave 3 PedsQL.
Conclusions. This novel study confi rmed previous cross-sectional associations, but did not provide convincing evidence that
BMI is causally associated with falling HRQoL or vice versa across the transition from childhood to adolescence.

Maternal predictors of preschool child-eating behaviours, food intake and body mass index : a prospective study

This study extends McPhie et al. (2011)'s [Maternal correlates of preschool child eating behaviours and body mass index: A cross-sectional study. International Journal of Pediatric Obesity, Early Online, 1–5.] McPhie et al. (2011)’s cross-sectional research, by prospectively evaluating maternal child-feeding practices, parenting style and mother–child interactions as predictors of child-eating behaviours, food habits and weight. A sample of 117 mothers of preschoolers (63 girls, 54 boys) participated at two time-points, Time 1 (T1) and Time 2 (T2), 12 months apart. Results from the two path models revealed maternal pressure to eat at T1 positively predicted change in child enjoyment of food. Maternal warmth at T1 negatively predicted child unhealthy food habits at T2. At T1, family income and maternal control negatively predicted change in child body mass index z-scores (BMIz); maternal pressure to eat at T1 also positively predicted change in child BMIz. There were significant results specific to each model. Both final path models provided an adequate fit. Our findings suggest childhood obesity is predicted by a complex interplay of demographic, maternal and child variables.

The association between television viewing and preschool child body mass index : a systematic review of english papers published from 1995 to 2010

This paper is a conceptual and methodological review of the literature on the impact of TV on preschoolers' weight status. A systematic search, of papers published between January 1995 and January 2010, identified twenty-six relevant studies. Fifteen of these were cross-sectional in design and eleven adopted a prospective design; a positive association between hours of TV and child adiposity was found in all but three studies. Although assessed in a limited number of studies, diet may mediate the relationship between TV viewing and BMI. Another likely mediator may be the content of TV programs watched; only three studies examined this association and findings were inconsistent. Our review revealed that research examining mediating effects is limited, focusing more on simple cross-sectional or prospective relationships between TV habits and child body mass index. Further investigation of the mechanisms by which TV viewing affects preschool weight gain is needed.

The neighborhood social environment and body mass index among youth : a mediation analysis

Background

This study aimed to examine associations between aspects of the neighborhood social environment and body mass index (BMI) in youth both cross-sectionally and prospectively; and whether this association was mediated by physical activity, screen-time and sedentary time.
Methods

Data were collected in 2004 and 2006 in high and low socio-economic areas of Melbourne, Australia. In 2004, 185 children aged 8-9 years (47% boys) and 359 children aged 13-15 years (45% boys) participated. Parents reported their perceptions of aspects of the social environment (i.e. social networks and social trust/cohesion), and physical activity (i.e. time spent outdoors by their children; and their younger children's walking and cycling trips) and screen-time (i.e. TV viewing, computer use). The older children self-reported their walking and cycling trips and their screen-time. All children wore an accelerometer to objectively assess outside-school hours moderate- to-vigorous physical activity and sedentary time. BMI was calculated from height and weight measured in 2004 and 2006. Multilevel linear regression analyses were conducted to examine associations between the social environment and BMI. Mediation analyses using the products of coefficient method were conducted to determine whether associations between the social environment and BMI were mediated by the time spent in a range of physical activity and sedentary behaviors.
Results

Cross-sectional and prospective regression analyses showed that a more positive social network and higher social trust/cohesion was related to lower BMI among children. There was no evidence that time spent in physical activity or sedentary behaviors mediated this relation, despite significant associations between social networks and screen-time and between screen-time and BMI.
Conclusions

The findings suggest that the neighborhood social environment may be important for preventing overweight and obesity in children. Further research investigating the mechanisms through which the neighborhood social environment exerts its effect on BMI is needed.

Australian Unity wellbeing index survey 25.1 part A : report "The wellbeing of Australians - bushfires and floods : following up the effects of fires in Victoria and floods in Queensland"

The Australian Unity Wellbeing Index monitors the subjective wellbeing of the Australian population. Our first survey was conducted in April 2001 and this report concerns a special Survey 25.1, undertaken in October 2011. The survey was commissioned to detect whether the disastrous floods in North Queensland in the period December 2010 through February 2011, and fires in Victoria in the period January through February 2009, continued to affect the subjective wellbeing of people continuing to live in the disaster areas.

This survey involved 1,215 respondents, with 600 drawn from Victoria and 615 from Queensland. The questionnaire comprised only the Personal Wellbeing Index and a small set of demographic questions. In all other respects the methodology of the survey followed our normal procedures.1

Measurement of the refractive index of soft contact lenses during wear

Purpose: To determine whether the refractive index (RI) of a soft contact lens can be evaluated using refractometry while the lens remains on the eye and to compare this with more traditional ex vivo RI measurements.

Methods: A slitlamp apparatus was modified to incorporate a customized Atago hand refractometer. With a double-masked study design, nine adapted symptomatic soft contact lens wearers wore a contact lens in each eye (lotrafilcon B and etafilcon A) in a randomized order. In vivo RI was determined from the relative Brix scale measurements immediately after lens insertion and after 1 and 10 hr of lens wear. Ex vivo refractometry was performed after 10 hr of lens wear for comparison. Means ± standard errors of the means are reported.

Results: In vivo RI values at baseline were 1.422 ± 0.0004 (lotrafilcon B) and 1.405 ± 0.0021 (etafilcon A); after 1 hr of lens wear, values were 1.423 ± 0.0006 and 1.408 ± 0.0007, respectively; and after 10 hr of lens wear, values were 1.424 ± 0.0004 and 1.411 ± 0.0010, respectively. Ex vivo RI values at the end of the 10 hr wearing period were 1.424 ± 0.0003 (lotrafilcon B) and 1.412 ± 0.0017 (etafilcon A). The change in in vivo RI across the day was statistically significant for the etafilcon A lens (repeated-measures analysis of variance, P<0.01) but not for the lotrafilcon B lens (P>0.05).

Conclusions: This novel adaptation of refractometry was able to measure the RI of soft contact lenses during wear (without lens removal). End of day RI measurements using in vivo and ex vivo refractometry were comparable with each other. Future work is required to determine whether this in vivo method can improve our understanding of the relationships between soft contact lens RI, hydration, on-eye lens performance, and symptomology.

The development of the Melbourne low vision ADL index : a measure of vision disability

PURPOSE. To develop a new test of activities of daily living (ADLs) appropriate for the low-vision population: the Melbourne Low-Vision ADL Index (MLVAI).

METHODS. The MLVAI was designed as a desk-based clinical assessment, comprising 18 observed items on complex ADLs in part (a) and 9 questions on broad self-care ADLs in part (b). Each item was rated on a five-level descriptive scale from 0 to 4, based on independence, speed, and accuracy of performance. It was designed to be administered under standardized conditions with regard to the instructions, illumination, and working distances. The validity and reliability of the new MLVAI was determined for 122 subjects who were representative of the general low-vision population, in a cross-sectional study.

RESULTS. Two items were found to be redundant and were eliminated from the test. Thus, the final test comprised 25 items, with 100 being the highest possible score. Cronbach’s α indicated an internal reliability of 0.96, and an intraclass correlation coefficient indicated an overall reliability of 0.95. The SE of measurement was 4.5. According to Spearman’s correlation coefficient, the test–retest reliability was 0.94 (P < 0.001), and the interpractitioner reliability for five different pairs of practitioners was 0.90 or higher (P < 0.001). With regard to validity, there was a moderately high correlation with vision impairment (r = −0.68, P < 0.001). Using Rasch analysis, content validity was also demonstrated by good separation indexes (4.70 and 9.88) and high reliability scores (0.96 and 0.99) for the person and items parameters, respectively. Separate calculation of indexes and reliability scores for parts (a) and (b) indicated high content validity and reliability of each part. However, the separation indexes and reliability scores were higher for part (a) than for part (b). The correlation coefficient for part (a) and part (b) was 0.68.

CONCLUSIONS. The MLVAI is a highly valid and reliable standardized test of ADL performance for the general low-vision population. It may be used to assess patients with low vision and has the potential to be used as a measure of low-vision rehabilitation outcomes.