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Objective: To evaluate the dependence of body mass index (BMI) values on pubertal stage in subjects similar in age., Design, Subjects and Measurements: Height and weight were recorded cross-sectionally in school subjects from three provinces in central Italy. The subjects were subdivided into three groups: (1) 4271 school subjects (2125 males and 2146 females; 8.5-15.5 y old), in whom the pubertal development was also recorded, were selected to subdivide BMI values according to pubertal stage and age; (2) 6345 females (10.5-14.5 y old), who were asked whether or not they had had their first menstrual period, were selected to subdivide BMI values according to age in pre-menarche and post-menarche girls, separately; and (3) 1919 females (10.5-14.5 y old), who had presented their menarche within the previous 6 months, were selected to subdivide short-term post-menarche BMI values according to age., Results: The medians and interquartile ranges of BMI varied according to age and pubertal stage. Kruskall-Wallis test performed in subjects similar in age demonstrated that significant differences existed among the medians of BMI values of subjects at different pubertal stages in 12-14-y-old males (P<0.05), and in 11-14-y- old females (P<0.001). The difference also proved to be significant between stage I and stage II (P<0.05) in 10-y-old females, but not in 10-11-y-old males. The Kruskal-Wallis test performed in subjects similar in pubertal stage demonstrated that significant differences among the medians of BMI at different ages existed only in females at stages II and III. A significant positive trend was observed in both genders according to pubertal stage for BMI values of subjects similar in age (z-test for trend, P<0.01). On the contrary, a negative age trend proved to be significant in females at stages I (P<0.01), II (P<0.01) and III (P<0.001), but not in males when the subdivision of BMI was made according to age in subjects similar in pubertal stage. BMI values were significantly higher in post-menarche girls as compared to pre-menarche girls similar in age (P<0.001). However, at partial regression analysis BMI values were influenced by pubertal stage and, to a lesser extent, by age, but not by menarcheal status. An inverse association between short-term post-menarche BMI and age was observed, with the highest values in girls presenting menarche at 11 y of age (P<0.05). The negative trend was demonstrated at the z-test for trend (P<0.001)., Conclusions: BMI values depend on pubertal degree of maturation, especially in girls. This influence should be taken into account when BMI is evaluated in adolescents., Sponsor: University of Perugia, Region of Umbria.

Objective: The influence of weight excess reduction on height and height velocity of obese subjects should be evaluated on the basis of appropriate standards, since the pattern of growth of obese subjects is different from that of normal weight subjects., Design, Subjects and Measurements: Height, weight and triceps skinfold thickness were recorded from 17987 school subjects (9256 males and 8731 females), 3-18 y of age, from three provinces of central Italy, and a growth reference curve of height was constructed. Using BMI (as computed using the tables of Rolland-Cachera et al) and triceps skinfold thickness, normal-weight subjects (NWS) and obese subjects (OS) were identified and specific reference curves (mean+/-s.d. every sixth month of age) were developed for both groups. Centiles of height were also calculated for OS. Various (2-4) measurements of height in school subjects were performed and a graph of height velocity (HV) was constructed in NWS and in OS using the JPPS method. The yearly mean +/-s.d. of HV was also calculated, based on square root transformed data (in order to realise a Gaussian distribution), deriving from successive measurements in total subjects, in NWS and in OS. The z-scores of height and of the square root of HV were calculated in 217 obese subjects (125 males and 92 females) before and during a weight excess reduction programme (WERP). Obese subjects in WERP who showed a reduction of z-score of BMI were considered as 'responsive'; those who either maintained or showed an increase of z-score of BMI were considered as 'non-responsive'. Obese subjects in WERP were followed for 1-4 y, giving the following results: 0-1 y, 142 responsives and 75 non-responsives; 0-2 y, 76 responsives and 33 non-responsives; 0-3 y, 35 responsives and 30 non-responsives; 0-4 y, 24 responsives and 18 non-responsives., Results: Compared to NWS, OS showed a significantly greater HV in 4-9y males and in 4-8y females, but in older children the pubertal spurt was reduced and more precocious. As a result, the height of OS, which was greater in 3-13 year-old males and in 3-11.5 year-old females, subsequently showed a reduction, as compared to that of NWS, in 16-18 year-old males and in 13-18 year-old females. In both responsive and non-responsive groups of obese subjects in WERP, the z-scores of height showed a reduction during WERP when evaluated using the reference curve of the total school population. In contrast, when their growth was evaluated according to the obese-specific reference curve, no significant variation was observed comparing both z-scores before and during the WERP., Conclusions: More appropriate information on the growth of obese subjects may be obtained when evaluating the height and HV according to obese-specific reference standards from the same population of origin. Adopting this modality, no significant variation of height resulted during WERP in obese children.