Kristin L. Sainani

Incidence patterns for ependymoma: a Surveillance, Epidemiology, and End Results study

OBJECT Previous small studies disagree about which clinical risk factors influence ependymoma incidence. The authors analyzed a large, population-based cancer registry to examine the relationship of incidence to patient age, sex, race, and tumor location, and to determine incidence trends over the past 3 decades. METHODS Data were obtained from the Surveillance, Epidemiology, and End Results (SEER-9) study, which was conducted from 1973 to 2003. Histological codes were used to define ependymomas. Age-adjusted incidence rates were compared by confidence intervals in the SEER*Stat 6.2 program. Multiplicative Poisson regression and Joinpoint analysis were used to determine annual percentage change and to look for sharp changes in incidence, respectively. RESULTS From the SEER database, 1402 patients were identified. The incidence rate per 100,000 person-years was significantly higher in male than in female patients (males 0.227 +/- 0.029, females 0.166 +/- 0.03). For children, the age at diagnosis differed significantly by tumor location, with the mean age for patients with infratentorial tumors calculated as 5 +/- 0.4 years; for supratentorial tumors it was 7.77 +/- 0.6 years, and for spinal lesions it was 12.16 +/- 0.8 years. (Values are expressed as the mean +/- standard error [SE].) Adults showed no difference in the mean age of incidence by location, although most tumors in this age group were spinal. Between 1973 and 2003, the incidence increased significantly among adults but not among children, and there were no sharp changes at any single year, both before and after age adjustment. CONCLUSIONS Males have a higher incidence of ependymoma than do females. A biological explanation remains elusive. Ependymoma occurs within the CNS at distinct locations at different ages, consistent with hypotheses postulating distinct populations of radial glial stem cells within the CNS. Ependymoma incidence appears to have increased over the past 3 decades, but only in adults.

Nutritional Factors That Influence Change in Bone Density and Stress Fracture Risk Among Young Female Cross-Country Runners

To identify nutrients, foods, and dietary patterns associated with stress fracture risk and changes in bone density among young female distance runners.

Both location and age predict survival in ependymoma: A SEER study

Studies have suggested that supratentorial ependymomas have better survival than infratentorial tumors, with spinal tumors having the best prognosis, but these data have been based on small samples. Using a population‐based registry of ependymomas, we analyzed how age, gender, location, race and radiotherapy influence survival in children.

Overuse Injuries in High School Runners: Lifetime Prevalence and Prevention Strategies

To evaluate lifetime prevalence and risk factors for overuse injuries in high school athletes currently participating in long‐distance running and provide recommendations for injury prevention strategies.

Identifying sex-specific risk factors for stress fractures in adolescent runners.

PURPOSE Adolescent females and males participating in running represent a population at high risk of stress fracture. Few investigators have evaluated risk factors for prospective stress fracture in this population. METHODS To better characterize risk factors for and incidence of stress fractures in this population, we collected baseline risk factor data on 748 competitive high school runners (442 girls and 306 boys) using an online survey. We then followed them prospectively for the development of stress fractures for a mean ± SD of 2.3 ± 1.2 total seasons of cross-country and track and field; follow-up data were available for 428 girls and 273 boys. RESULTS We identified prospective stress fractures in 5.4% of girls (n = 23) and 4.0% of boys (n = 11). Tibial stress fractures were most common in girls, and the metatarsus was most frequently fractured in boys. Multivariate regression identified four independent risk factors for stress fractures in girls: prior fracture, body mass index < 19, late menarche (age menarche ≥15 yr), and previous participation in gymnastics or dance. For boys, prior fracture and increased number of seasons were associated with an increased rate of stress fractures, whereas prior participation in basketball was associated with a decreased risk of stress fractures. CONCLUSIONS Prior fracture represents the most robust predictor of stress fractures in both sexes. Low body mass index, late menarche, and prior participation in gymnastics and dance are identifiable risk factors for stress fractures in girls. Participation in basketball appears protective in boys and may represent a modifiable risk factor for stress fractures. These findings may help guide future translational research and clinical care in the management and prevention of stress fractures in young runners.

The Problem of Multiple Testing

K o v 9 e D alse-positive results that arise as the result of chance are common in the medical literature 1-3]. By chance, every study sample will have slight imbalances that don’t reflect the whole opulation. If researchers look at enough characteristics of a given sample, they are bound o discover these quirks and conclude (mistakenly) that they have significance for the whole opulation. This is the problem of multiple testing—the more tests you run on a sample, the reater the likelihood of a chance finding. This article will formally describe the problem of ultiple testing and give readers tools for spotting chance findings in the literature.

Evaluating the Relationship of Calcium and Vitamin D in the Prevention of Stress Fracture Injuries in the Young Athlete: A Review of the Literature

Calcium and vitamin D are recognized as 2 components of nutrition needed to achieve and maintain bone health. Calcium and vitamin D have been clearly shown to improve bone density and prevent fractures at all ages. However, the literature is conflicting as to the role of these nutrients in young athletes ages 18 to 35 years, both for bone development and for the prevention of bone overuse injuries. Differences in findings may relate to study design. Although retrospective and cross‐sectional studies have had mixed results, the authors of prospective studies have consistently demonstrated a relationship of increased calcium intake with an improvement in bone density and a decrease in fracture risk. A randomized trial in female military recruits demonstrated that calcium/vitamin D supplementation reduced the incidence of stress fractures. A prospective study in young female runners demonstrated reduced incidence of stress fractures and increased bone mineral density with increased dietary calcium intake. Findings from both studies suggest female athletes and military recruits who consumed greater than 1500 mg of calcium daily exhibited the largest reduction in stress fracture injuries. To date, no prospective studies have been conducted in male athletes or in adolescent athletes. In most studies, males and nonwhite participants were poorly represented. Evidence regarding the relationship of vitamin D intake with the prevention of fractures in athletes is also limited. More prospective studies are needed to evaluate the role of calcium and vitamin D intake in prevention of stress fracture injuries in both male and female adolescent athletes, particularly those participating in sports with greater incidences of stress fracture injury.

Higher Caloric Intake in Hospitalized Adolescents With Anorexia Nervosa Is Associated With Reduced Length of Stay and No Increased Rate of Refeeding Syndrome

PURPOSE To determine the effect of higher caloric intake on weight gain, length of stay (LOS), and incidence of hypophosphatemia, hypomagnesemia, and hypokalemia in adolescents hospitalized with anorexia nervosa. METHODS Electronic medical records of all subjects 10-21 years of age with anorexia nervosa, first admitted to a tertiary childrens hospital from Jan 2007 to Dec 2011, were retrospectively reviewed. Demographic factors, anthropometric measures, incidence of hypophosphatemia (≤3.0 mg/dL), hypomagnesemia (≤1.7 mg/dL), and hypokalemia (≤3.5 mEq/L), and daily change in percent median body mass index (BMI) (%mBMI) from baseline were recorded. Subjects started on higher-calorie diets (≥1,400 kcal/d) were compared with those started on lower-calorie diets (<1,400 kcal/d). RESULTS A total of 310 subjects met eligibility criteria (age, 16.1 ± 2.3 years; 88.4% female, 78.5 ± 8.3 %mBMI), including 88 in the lower-calorie group (1,163 ± 107 kcal/d; range, 720-1,320 kcal/d) and 222 in the higher-calorie group (1,557 ± 265 kcal/d; range, 1,400-2,800 kcal/d). Neither group had initial weight loss. The %mBMI increased significantly (p < .001) from baseline by day 1 in the higher-calorie group and day 2 in the lower-calorie group. Compared with the lower-calorie group, the higher-calorie group had reduced LOS (13.0 ± 7.3 days versus 16.6 ± 9.0 days; p < .0001), but the groups did not differ in rate of change in %mBMI (p = .50) or rates of hypophosphatemia (p = .49), hypomagnesemia (p = 1.0), or hypokalemia (p = .35). Hypophosphatemia was associated with %mBMI on admission (p = .004) but not caloric intake (p = .14). CONCLUSIONS A higher caloric diet on admission is associated with reduced LOS, but not increased rate of weight gain or rates of hypophosphatemia, hypomagnesemia, or hypokalemia. Refeeding hypophosphatemia depends on the degree of malnutrition but not prescribed caloric intake, within the range studied.

The Importance of Accounting for Correlated Observations

Correlated data arise when pairs or clusters of observations are related and thus are more similar to each other than to other observations in the dataset. Observations may be related because they come from the same subject—for example, when subjects are measured at multiple time points (repeated measures) or when subjects contribute data on multiple body parts, such as both eyes, hands, arms, legs, or sides of the face. Observations from different subjects also may be related—for example, if the dataset contains siblings, twin pairs, husband-wife pairs, control subjects who have been matched to individual cases, or patients from the same physician practice, clinic, or hospital. Cluster randomized trials, which are performed to assign interventions to groups of people rather than to individual subjects (for example, schools, classrooms, cities, clinics, or communities), also are a source of correlated data because subjects within a cluster will likely have more similar outcomes than subjects in other clusters.

Incidence patterns of central nervous system germ cell tumors: a SEER Study.

Background Incidence patterns of central nervous system (CNS) germ cell tumors (GCTs) have been reported, but the influence of underlying host risk factors has not been rigorously explored. We aimed to determine in a large, population-based cancer registry how age, sex, and race, influence the occurrence of CNS GCTs in the pediatric population. Methods Using the Surveillance, Epidemiology, and End Results registry, we identified cases of histologically confirmed GCTs in children, adolescents, and young adults (age 0 to 29 y), diagnosed between 1973 and 2004. The cases were limited to only those with the International Classification of Childhood Cancer Xa: intracranial and intraspinal germ-cell tumors. Incidence rates (per 10,000) for each sex and race were plotted for single-age groups, and then stratified by tumor location and pathology subtype. Results The sample included a total of 638 cases (490 males). Males had significantly higher rates of CNS GCTs than females. Male and female rates diverged significantly starting at the age of 11 years and remained widely discrepant until the age of 30 years. There were more germinomas than nongerminomas in both sexes. Germinomas peaked in incidence during adolescence, whereas nongerminoma incidence remained relatively constant in children and young adults. Tumor location differed strikingly by sex (P<0.0001) with pineal location more common in males (61.0% vs. 15.5%). Asian race was associated with a higher rate of CNS GCTs than other races. Conclusions Males have higher incidence of CNS GCTs, primarily germinomas, than females, starting in the second decade. Pineal location is strongly associated with male sex, with pineal germinomas representing over half of all CNS GCTs in males. Asian-Americans have higher rates than other races. These findings suggest a robust but poorly understood influence of sex, either genetic or hormonal, and race on the occurrence of CNS GCTs.