2 Minute Medicine Rewind February 24th – March 2nd, 2014
In this section, we will highlight the key high-impact studies, updates, and analyses published in medicine during the past week.
Prevalence of Childhood and Adult Obesity in the United States, 2011-2012
Over the past half century, an increasing proportion of the United States population are overweight or obese. To provide more timely estimates of obesity, investigators compared 9120 participants in the National Health and Nutrition Examination Survey with data from previous studies. In 2011-2012, 8.1% of infants and toddlers had high weight for length, 16.9% of 2-19 year olds were obese, and 34.9% of adults were obese. These results were largely unchanged from the NHNES survey from 2003-2004. There was a decrease in obesity among 2-5 year old children (from 13.9% in 2003-2004 to 8.4% in 2011-2012, = 0.03) and an increase in obesity in women older than 60 years old (31.5% to 38.1%, p = 0.006). There were no significant changes in obesity prevalence in the United States as found by the NHNES surveys in 2003-2004 and 2011-2012, however the rates of obesity in the United States is still high.
Noninvasive Prenatal Testing in Low-Risk Pregnancy
Sequencing of maternal plasma cell-free DNA is a relatively new, noninvasive but expensive modality for risk-stratification of autosomal aneuploidy in high risk pregnancies. In this multicenter, cohort study of 1914 pregnant women from 21 centers, investigators studied the utility of cfDNA testing in singleton pregnancies in comparison to standard aneuploidy screening including biochemical assays and nuchal translucency). The investigators found a significantly decreased rate of false positives (0.3% vs. 3.6% for trisomy 21, p < 0.001 and 0.2% vs. 0.6% for trisopy 18, p = 0.03). In this population, cfDNA testing had a negative predictive value of 100% (95% CI of 99.8 – 100%) and positive predictive values of 45.5% for trisomy 21 (vs. 4.2% by standard screening), 40.0% for trisomy 18 (vs. 8.3%). This new, noninvasive screening modality seems to have improved operating characteristics compared to standard care for all pregnancies.
It is difficult to study the long term health effects of environmental exposure to air pollution. In this retrospective analysis of 22 European cohorts, investigators studied a population of 367 251 participants and correlated local exposure to air pollutants with metrics including local traffic intensity and annual average concentrations of particulate matter. In their study, there was an increased hazard ratio for natural cause mortality with annual concentrations of particulate matter with diameters less than 2.5 μm (HR 1.07, 95% CI 1.02-1.13). There was a dose dependent relationship even at concentrations below European annual mean limits of 25 μg/m3 (HR 1.06, 95% CI 1.00-1.12) or below 20 μg/m3(1.07, 1.01-1.13). There appears to be an increase in natural cause mortality from long term exposure to fine particulate matter.
National efforts in improving primary care access and quality include interventions to create patient-centered medical homes however there is limited long term data on their quality or ability to contain costs. In this study of 32 primary care practices piloting the medical homes model in southeastern Pennsylvania, investigators examined claims data from the pilot programs start in June 2008 and its end in May 2011. The 32 primary care practices adopted structural capabilities including patient registries and wass recognized by the National Committee for Quality Assurance. Only in 1 of 11 quality measures (nephropathy screening in diabetics) was there an improvement of performance (82.7% vs. 71.7% at baseline, p < 0.001). There were no statistically significant changes in cost or utilization of hospital, emergency department, or ambulatory care services. Additional work needs to be done to refine the medical home model and incentive increased quality and lower costs.
Colorectal cancer screening, whether through colonoscopy, sigmoidoscopy, or fecal occult blood testing, is recommended by numerous national and topic societies. The United States Preventative Services Task Force recommends colorectal cancer screening starting at age 50 and continuing until age 75, however some practitioners advocate the decision to screen to be based on life expectancy instead of age alone. In this retrospective cohort study, investigators looked at the incidence of colorectal screening of 399 067 veterans greater than age 50 enrolled in the Veterans Affairs Health Care System. The authors found that 38% of the study population had documented screening within the last two years, with significantly less screening after age 75 (adjusted relative risk 0.35, 95% CI 0.30-0.40). Additionally, sick veterans over the age of 75 with more encounters with the healthcare system were actually more likely to receive colorectal cancer screening than a healthy veteran over age 75 (unadjusted relative risk 1.64, 95% CI 1.36 – 1.97). There should be a rank discussion of risk/benefit ratio of all patients in cancer screening and the rates of receiving an intervention should reflect the likelihood of receiving benefit.
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