Comparison of Quantile Regression and Gaussian (Z-scores) Percentiles to BSA in Growth Charts With a Pakistani Population.

Introduction

In the current study, we construct growth charts of body surface area (BSA) for adults using the quantile regression (QR) approach and growth charts of different Gaussian Percentiles (Z-scores) against age.

Methods

A cross-sectional data consisting of 3,473 individuals aged 5 or more, both males and females were taken from Multan city. Quantile regression (QR) was used to construct BSA growth charts. Growth charts for different Z-scores were also constructed.

Results

For our data set, the mean BSA is 0.48750. The BSA percentiles show a trending higher after the age of 5 until the age of 22, then decrease between age 22 and 35, and then finally increase after age 35. The Z-score curve increases slightly after age 5 and then proceeds higher until age 22. After age 22 and before 35 it plateaus and then increases slightly after age 35.

Conclusion

Since the use of empirical BSA percentiles and Z-scores with grouped age provides a discrete approximation for the population percentiles and Z-scores, it is more accurate to use continuous BSA percentile and Z-score, curves against given ages while using quantile regression and Z-score approach. Furthermore, this approach can also be adopted to construct many other growth charts for physiological and medical sciences.