Dorothy Kim Waller

The population-based prevalence of achondroplasia and thanatophoric dysplasia in selected regions of the US†

There have been no large population‐based studies of the prevalence of achondroplasia and thanatophroic dysplasia in the United States. This study compared data from seven population‐based birth defects monitoring programs in the United States. We also present data on the association between older paternal age and these birth defects, which has been described in earlier studies. The prevalence of achondroplasia ranged from 0.36 to 0.60 per 10,000 livebirths (1/27,780–1/16,670 livebirths). The prevalence of thanatophoric dysplasia ranged from 0.21 to 0.30 per 10,000 livebirths (1/33,330–1/47,620 livebirths). In Texas, fathers that were 25–29, 30–34, 35–39, and ≥40 years of age had significantly increased rates of de novo achondroplasia among their offspring compared with younger fathers. The adjusted prevalence odds ratios were 2.8 (95% CI; 1.2, 6.7), 2.8 (95% CI; 1.0, 7.6), 4.9 (95% CI; 1.7, 14.3), and 5.0 (95% CI; 1.5, 16.1), respectively. Using the same age categories, the crude prevalence odds ratios for de novo cases of thanatophoric dysplasia in Texas were 5.8 (95% CI; 1.7, 9.8), 3.9 (95% CI; 1.1, 6.7), 6.1 (95% CI; 1.6, 10.6), and 10.2 (95% CI; 2.6, 17.8), respectively. These data suggest that thanatophoric dysplasia is one‐third to one‐half as frequent as achondroplasia. The differences in the prevalence of these conditions across monitoring programs were consistent with random fluctuation. Birth defects monitoring programs may be a good source of ascertainment for population‐based studies of achondroplasia and thanatophoric dysplasia, provided that diagnoses are confirmed by review of medical records.

Is maternal parity an independent risk factor for birth defects

BACKGROUND Although associations between maternal parity and birth defects have been observed previously, few studies have focused on the possibility that parity is an independent risk factor for birth defects. We investigated the relation between levels of parity and a range of birth defects, adjusting each defect group for the same covariates. METHODS We included infants who had an estimated delivery date between 1997 and 2007 and participated in the National Birth Defects Prevention Study, a multisite case-control study. Cases included infants or fetuses belonging to 38 phenotypes of birth defects (n = 17,908), and controls included infants who were unaffected by a major birth defect (n = 7173). Odds ratios (ORs) were adjusted for 12 covariates using logistic regression. RESULTS Compared with primiparous mothers, nulliparous mothers were more likely to have infants with amniotic band sequence, hydrocephaly, esophageal atresia, hypospadias, limb reduction deficiencies, diaphragmatic hernia, omphalocele, gastroschisis, tetralogy of Fallot, and septal cardiac defects, with significant ORs (1.2 to 2.3). Compared with primiparous mothers, multiparous mothers had a significantly increased risk of omphalocele, with an OR of 1.5, but had significantly decreased risk of hypospadias and limb reduction deficiencies, with ORs of 0.77 and 0.77. CONCLUSIONS Nulliparity was associated with an increased risk of specific phenotypes of birth defects. Most of the phenotypes associated with nulliparity in this study were consistent with those identified by previous studies. Research into biologic or environmental factors that are associated with nulliparity may be helpful in explaining some or all of these associations.

Use of Oral Contraceptives in Pregnancy and Major Structural Birth Defects in Offspring

Background: Oral contraceptives (OCs) are the most commonly used reversible contraceptive method among US women. Although the majority of previous studies have reported no association between OC use during pregnancy and birth defects, some studies have reported increased occurrence of neural tube defects, limb reduction defects, and urinary tract anomalies. Methods: We assessed OC use among mothers who participated in the multisite, case-control, National Birth Defects Prevention Study. Mothers of 9986 infants with 32 types of birth defects and 4000 infants without birth defects were included. Results: Maternal OC use during the first 3 months of pregnancy was associated with an increased odds ratio for 2 of 32 birth defects: hypoplastic left heart syndrome (adjusted odds ratio = 2.3 [95% confidence interval = 1.3–4.3) and gastroschisis (1.8 [1.3–2.7]). Conclusion: Previous reports of associations between OC use and specific types of anomalies were not corroborated. Given that associations were assessed for 32 types of birth defects, our findings of 2 increased associations between OC use and gastroschisis and hypoplastic left heart syndrome should be interpreted as hypotheses until they can be evaluated further. Overall, our findings are consistent with the majority of previous studies that found women who use OCs during early pregnancy have no increased risk for most types of major congenital malformations.

Maternal use of hot tub and major structural birth defects

BACKGROUND Previous studies on the associations between hot tub use during early pregnancy and birth defects have found an increased risk of neural tube defects, but no increase in risk of cardiac defects. No previous studies have assessed the association between maternal hot tub use and other types of noncardiac birth defects. METHODS We included mothers of infants with birth defects (n = 10,825) and mothers of infants without birth defects (n = 6795) who participated in the multisite National Birth Defects Prevention Study between 1997 and 2005. Odds ratios were adjusted for maternal ethnicity and education. RESULTS Analysis of 17 birth defects revealed that mothers of infants with gastroschisis and anencephaly were significantly more likely to report any use of a hot tub in early pregnancy: adjusted odd ratios were 1.54 (95% confidence interval [CI], 1.10-2.17) and 1.68 (95% CI, 1.05-2.70), respectively. Among the mothers who reported using a hot tub more than once in the exposure period and remaining in it for more than 30 min, we found significantly elevated odds ratios (≥2.0) for esophageal atresia, omphalocele, and gastroschisis and a nonsignificant elevation (≥2.0) for spina bifida and anencephaly. CONCLUSIONS These results suggest that women who use hot tubs more than once during early pregnancy and for long periods of time have an increased risk of certain birth defect phenotypes, particularly anencephaly and gastroschisis. Because of multiple statistical tests and small sample sizes, we cannot exclude the possibility that some of these elevated associations may be due to chance.

An evaluation of differences in risk factors for individual types of surgical site infections after colon surgery

BACKGROUND Most studies and national programs aggregate the different types of surgical site infections (SSIs) potentially masking and misattributing risk. Determining that risk factors for superficial, deep, and organ space SSIs are unique is essential to improve SSI rates. METHODS This cohort study utilized data of 59,365 patients who underwent colon resection at hospitals participating in the American College of Surgeons National Surgical Quality Improvement Program from 2007 to 2009. Four independent, multivariable, predictive models were developed to assess the unique associations between risk factors and each SSI group: Superficial, deep, organ space, and an aggregate of all 3 types of SSIs. RESULTS Overall, 13% of colon cases developed SSIs: Superficial (8%), deep (1.4%), and organ space (3.8%). Each model was different. Morbidly obese patients were more likely to develop SSIs than normal weight patients across all models; however, risk factors common to all models (eg, body mass index [BMI], duration of operation, wound class, laparoscopic approach) had very different levels of risk. Unique risks for superficial SSIs include diabetes, chronic obstructive pulmonary disease, and dyspnea. Deep SSIs had the greatest magnitude of association with BMI and the greatest incidence of wound disruption (19.8%). Organ space SSIs were often owing to anastomotic leaks and were uniquely associated with disseminated cancer, preoperative dialysis, preoperative radiation treatment, and a bleeding disorder, suggesting a physically frail or compromised patient may put the anastomosis at risk. CONCLUSION Risk factors for superficial, deep, and organ space SSI differ. More effective prevention strategies may be developed by reporting and examining each type of SSI separately.

Place of Death among Hospitalized Patients with Cancer at the End of Life

BACKGROUND The majority of hospital deaths in the United States occur after ICU admission. The characteristics associated with the place of death within the hospital are not known for patients with cancer. OBJECTIVE The study objective was to identify patient characteristics associated with place of death among hospitalized patients with cancer who were at the end of life. METHODS A retrospective cohort study design was implemented. Subjects were consecutive patients hospitalized between 2003 and 2007 at a large comprehensive cancer center in the United States. Multinomial logistic regression analysis was used to identify patient characteristics associated with place of death (ICU, hospital following ICU, hospital without ICU) among hospital decedents. RESULTS Among 105,157 hospital discharges, 3860 (3.7%) died in the hospital: 42% in the ICU, 14% in the hospital following an ICU stay, and 44% in the hospital without ICU services. Individuals with the following characteristics had an increased risk of dying in the ICU: nonlocal residence, newly diagnosed hematologic or nonmetastatic solid tumor malignancies, elective admission, surgical or pediatric services. A palliative care consultation on admission was associated with dying in the hospital without ICU services. CONCLUSIONS Understanding existing patterns of care at the end of life will help guide decisions about resource allocation and palliative care programs. Patients who seek care at dedicated cancer centers may elect more aggressive care; thus the generalizability of this study is limited. Although dying in a hospital may be unavoidable for patients who have uncontrolled symptoms that cannot be managed at home, palliative care consultations with patients and their families in advance regarding end-of-life preferences may prevent unwanted admission to the ICU.

Two Decades of ICU Utilization and Hospital Outcomes in a Comprehensive Cancer Center.

Objective:To investigate ICU utilization and hospital outcomes of oncological patients admitted to a comprehensive cancer center. Design:Observational cohort study. Setting:The University of Texas MD Anderson Cancer Center. Patients:Consecutive adults with cancer discharged over a 20-year period. Interventions:None. Measurements and Main Results:The Cochran-Armitage test for trend was used to evaluate ICU utilization and hospital mortality rates by primary service over time. A negative binomial log linear regression model was fitted to the data to investigate length of stay over time. Among 387,306 adult hospitalized patients, the ICU utilization rate was 12.9%. The overall hospital mortality rate was 3.6%: 16.2% among patients with an ICU stay and 1.8% among non-ICU patients. Among those admitted to the ICU, the mean (SD) admission Sequential Organ Failure Assessment score was 6.1 (3.8) for all ICU patients: 7.3 (4.4) for medical ICU patients and 4.9 (2.8) for surgical ICU patients. Hematologic disorders were associated with the highest hospital mortality rate in ICU patients (42.8%); metastatic disease had the highest mortality rate in non-ICU patients (4.2%); sepsis, pneumonia, and other infections had the highest mortality rate for all inpatients (8.5%). Conclusions:This study provides a longitudinal view of ICU utilization rates, hospital and ICU length of stay, and severity-adjusted mortality rates. Although the data arise from a single institution, it encompasses a large number of hospital admissions over two decades and can serve as a point of comparison for future oncological studies at similar institutions. More studies of this nature are needed to determine whether consolidation of cancer care into specialized large-volume facilities may improve outcomes, while simultaneously sustaining appropriate resource utilization and reducing unnecessary healthcare costs.

Maternal occupational exposure to ionizing radiation and major structural birth defects

BACKGROUND Ionizing radiation (IR) is known to be carcinogenic and mutagenic, but little is known about the association between maternal occupational exposure to IR and birth defects. METHODS We studied 38,009 mothers who participated in the National Birth Defects Prevention Study and delivered between 1997 and 2009. We assessed odds ratios [ORs] for the association between maternal occupations with potential exposure to IR and 39 birth defects. RESULTS We observed significant odds ratios (ORs) for isolated hydrocephaly (adjusted OR [AOR], 2.1; 95% confidence interval [CI], 1.1-4.2), isolated anotia/microtia (AOR, 2.0; 95% CI, 1.0-4.0), isolated colonic atresia (crude OR, 7.5; 95% CI, 2.5-22.3), isolated omphalocele (AOR, 2.3; 95% CI, 1.1-4.6) and isolated anencephaly (crude OR, 0.23; 95% CI, 0.06-0.94). We also observed a nonsignificant OR for birth defects in aggregate (AOR, 2.0; 95% CI, 0.9-4.6) among mothers with potential occupational exposure to fluoroscopy. CONCLUSION We assessed 39 birth defects, observing that maternal occupations with potential exposure to IR were associated with a significantly increased risk for 4 birth defects and a significantly protected risk for 1 birth defect. These results should be interpreted cautiously because our measurement of exposure is qualitative, some of these associations may be due to occupational exposures that are correlated with IR and some may be due to chance. However, these findings serve as the first evaluation of these relationships in a large study and may be useful for generating hypotheses for future studies.

Thyroid Medication Use and Birth Defects in the National Birth Defects Prevention Study

BACKGROUND Thyroid disorders are common among reproductive-aged women, with hypothyroidism affecting 2 to 3% of pregnancies, and hyperthyroidism affecting an additional 0.1 to 1%. We examined associations between thyroid medications and individual birth defects using data from the National Birth Defects Prevention Study (NBDPS). METHODS The NBDPS is a multisite, population-based, case-control study that included pregnancies with estimated delivery dates from 1997 to 2011. We analyzed self-reported thyroid medication use from mothers of 31,409 birth defect cases and 11,536 unaffected controls. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using logistic regression for birth defects with five or more exposed cases, controlling for maternal age, race/ethnicity, and study center. Crude ORs and exact 95% CIs were estimated for defects with 3 to 4 exposed cases. RESULTS Thyroid hormone was used by 738 (2.3%) case and 237 (2.1%) control mothers, and was associated with anencephaly (OR = 1.68; 95% CI, 1.03-2.73), holoprosencephaly (OR = 2.48; 95% CI, 1.13-5.44), hydrocephaly (1.77; 95% CI, 1.07-2.95) and small intestinal atresia (OR = 1.81; 95% CI, 1.04-3.15). Anti-thyroid medication was used by 34 (0.1%) case and 10 (<0.1%) control mothers, and was associated with aortic valve stenosis (OR = 6.91; 95% CI, 1.21-27.0). CONCLUSION While new associations were identified, our findings are relatively consistent with previous NBDPS analyses. Our findings suggest thyroid medication use is not associated with most birth defects studied in the NBDPS, but may be associated with some specific birth defects. These results should not be interpreted to suggest that medications used to treat thyroid disease are teratogens, as the observed associations may reflect effects of the underlying thyroid disease. Birth Defects Research 109:1471-1481, 2017.© 2017 Wiley Periodicals, Inc.

Sociodemographic and hispanic acculturation factors and isolated anotia/microtia

BACKGROUND It has been observed in several studies that infants with anotia/microtia are more common among Hispanics compared with other racial/ethnic groups. We examined the association between selected Hispanic ethnicity and acculturation factors and anotia/microtia in the National Birth Defects Prevention Study. METHODS We examined data from mothers of 351 infants with isolated anotia/microtia and 8435 unaffected infants from the National Birth Defects Prevention Study with an expected delivery date from 1997 to 2007. Sociodemographic, maternal, and acculturation factors (e.g., age, maternal education, household income, body mass index, gestational diabetes, folic acid, smoking, alcohol intake, study center, parental birthplace, and years lived in the United States, maternal language) were assessed as overall risk factors and also as risk factors among subgroups of Hispanics (United States- and foreign-born) versus non-Hispanic whites. RESULTS Compared with non-Hispanic whites, both United States- and foreign-born Hispanic mothers demonstrated substantially higher odds of delivering infants with anotia/microtia across nearly all strata of sociodemographic and other maternal factors (adjusted odds ratios range: 2.1-11.9). The odds of anotia/microtia was particularly elevated among Hispanic mothers who emigrated from Mexico after age five (adjusted odds ratios = 4.88; 95% confidence interval = 2.93-8.11) or who conducted the interview in Spanish (adjusted odds ratios = 4.97; 95% confidence interval = 3.00-8.24). CONCLUSION We observed that certain sociodemographic and acculturation factors are associated with higher risks of anotia/microtia among offspring of Hispanic mothers.