Ethnic Differences in the Presence of Secondary Sex Characteristics and Menarche Among US Girls: The Third National Health and Nutrition Examination Survey, 1988–1994
Wu T, Mendola P, Buck GM. Pediatrics 2002; 110: 752–757.
A study by HermanGiddens et al in 1997 (Pediatrics 1997; 99: 505–512) created a great deal of publicity and debate about the normal age of onset of puberty in girls. That study of 17,000 girls reported that the mean age at the onset of pubic hair development in African-American girls and white girls was 8.78 and 10.51 years, respectively. Breast development occurred at 8.87 and 9.96 years, respectively, and menarche occurred at 12.16 and 12.88 years, respectively. The controversy was related to the reports that 30% of African-American girls had breast and pubic hair development at 8 years and 30% of Caucasian girls had breast development at 8 years raising issues related to the earlier age of onset of puberty in girls. In order to evaluate secular trends in the ages of secondary sexual development related to race and ethnicity, the authors of this report evaluated data from the Third National Health and Nutrition Examination Survey (NHANES III) to determine the prevalence of pubic hair, breast development, and menarche in non-Hispanic white girls, African-American girls, and Mexican-American girls.
Methods and Results:
The NHANES III data were stratified to obtain representative health and nutrition information. Girls were evaluated by trained examiners. One thousand six hundred twenty-three girls aged 8–16 were included in the analysis for breast and pubic hair development and 1168 girls for the menarche assessments. There were similar numbers of non-Hispanic white girls, African-American girls, and Mexican-American girls. The results demonstrate that African-American girls and Mexican-American girls had earlier pubertal development than non-Hispanic white girls. The mean ages at onset of pubic hair, thelarche, and menarche were 9.5, 9.5, and 12.1 years for African-American girls; 10.3, 9.8, and 12.2 for Mexican-American girls; and 10.5, 10.3, and 12.7 years for non-Hispanic white girls. The data were also corrected for body mass index and socioeconomic variables. Even after this correction, the ethnic differences remained.
This study confirms studies that indicate that there are ethnic differences in the age of the onset of puberty, even after taking differences in body mass index into account. The reasons for these differences (genetic vs. environmental) are not known and are deserving of further investigation. (OP)
Clinical Use of Bone Densitometry
Cummings SR, Black DM. Scientific Review, JAMA 2002; 288: 1889–1897.
Bates DW, Black DM, Cummings SR. Clinical Applications, JAMA 2002; 288: 1898–1900.
Bone densitometry is a critical part of diagnosis and management of osteoporosis and has become more widely available. Its use is still limited, not only by cost but also by confusion on the part of physicians as to its interpretation.
These two articles from the UCSF Coordinating Center, which has been a leader in epidemiologic studies and clinical trials in osteoporosis, are an attempt to clarify the clinical issues and help the practitioner make effective, evidence-based decisions.
Materials and Methods:
The Scientific Review uses published data, including the evidence on fracture risk from the Study of Osteoporotic Fractures, to assess the relation of bone density, determined by DEXA of the spine and hip, to 5-year fracture risk. The recommendation for universal screening by hip or spine DEXA at the age of 65 originally put forward by the National Osteoporosis Foundation has now been reinforced by the US Preventative Services Task Force (Ann Intern Med 2002; 137: 526). The other methods for measuring BMD are also reviewed, and their limitations for making clinical decisions pointed out. The provision of 5-year fracture risk data for women older than 65 is particularly useful because it allows the clinician to reinforce the recommendations for or against antiresorptive therapy based on realistic estimates of both the increase in risk in the individual patient and the potential reduction of that risk by treatment. However, one problem in these estimates is that we really do not have adequate information on the long-term impact of a conservative regiment of calcium, vitamin D, and exercise in patients at low-to-moderate risk.
In the paper on Clinical Applications the authors provide a series of case vignettes to answer the questions, “Who should be tested?”, “What tests should be performed?”, and “What about the follow-up testing?” An algorithm for evaluating the osteoporosis-fracture risk is presented.
These well-written, succinct papers should be extremely useful to clinicians in providing guidance in the diagnosis and management of osteoporosis. The emphasis on using hip BMD is evidence-based; however, most bone densitometry centers measure both hip and spine at no extra cost. The spine measurement is useful in younger individuals who are less likely to have degenerative changes and clinical trials have been carried out using low spinal BMD and vertebral fractures as entry criteria. The authors correctly point out that screening is underutilized and makes some useful suggestions for increasing utilization in a primary care setting. (LR)