CALCULATION OF KNEMOMETRIC GROWTH-RATES IN GROUP STUDIES OF CHILDREN TREATED WITH EXOGENOUS GLUCOCORTICOIDS

Calculation of growth rates in short-term knemometry studies is often based on linear regression analysis. The method, however, has not been compared to the conventional method for calculation of growth rates ( increase in length divided by the time interval) in glucocorticoid-tre ated populations. The aim of the present study was to assess whether t he conventional method for calculation of growth rates is as sensitive as the linear regression method in the assessment of short-term lower leg growth in group studies of children treated with exogenous glucoc orticoids. Three different studies were conducted during which knemome try was performed once or twice weekly. Six boys and six girls aged 5- 12 years, with atopic dermatitis, participated in an open longitudinal study with three periods of 2 weeks duration. Ten boys and four girls aged 12-16 years, with asthma, were studied in a randomized double-bl ind, placebo-controlled two-period crossover trial, with treatment per iods of 4 weeks. Thirteen boys and 11 girls aged 5-12 years, with asth ma, were enrolled in a randomized double-blind two-period crossover tr ial with treatment periods of 4 weeks. During active treatment periods topical budesonide was given. Mean lower leg growth rates and the res ults of significance tests based on the two methods for calculation of growth rates were similar in all studies. Significant correlations be tween the growth rates based on the two methods were found in the non- glucocorticoid and glucocorticoid treatment periods in all studies (Pe arson correlation r coefficient varied from 0.81 to 0.97, p from <0.00 1 to < 0.0001). The conventional method for calculation of lower leg g rowth rates is as reliable as linear regression analysis. By using the conventional method the number of visits required for knemometric gro wth rate assessment in group studies of systemic activity of exogenous glucocorticoids can be reduced.