Publications

Roux-en-Y gastric bypass (RYGB) surgery has negative effects on bone, mediated in part by effects on nutrient absorption. Not only can RYGB result in vitamin D malabsorption, but the bypassed duodenum and proximal jejunum are also the predominant sites of active, transcellular, 1,25(OH)2 D-mediated calcium (Ca) uptake. However, Ca absorption occurs throughout the intestine, and those who undergo RYGB might maintain sufficient Ca absorption, particularly if vitamin D status and Ca intake are robust. We determined the effects of RYGB on intestinal fractional Ca absorption (FCA) while maintaining ample 25OHD levels (goal ≥30 ng/mL) and Ca intake (1200 mg daily) in a prospective cohort of 33 obese adults (BMI 44.7 ± 7.4 kg/m(2)). FCA was measured preoperatively and 6 months postoperatively with a dual stable isotope method. Other measures included calciotropic hormones, bone turnover markers, and BMD by DXA and QCT. Mean 6-month weight loss was 32.5 ± 8.4 kg (25.8% ± 5.2% of preoperative weight). FCA decreased from 32.7% ± 14.0% preoperatively to 6.9% ± 3.8% postoperatively (p < 0.0001), despite median (interquartile range) 25OHD levels of 41.0 (33.1 to 48.5) and 36.5 (28.8 to 40.4) ng/mL, respectively. Consistent with the FCA decline, 24-hour urinary Ca decreased, PTH increased, and 1,25(OH)2 D increased (p ≤ 0.02). Bone turnover markers increased markedly, areal BMD decreased at the proximal femur, and volumetric BMD decreased at the spine (p < 0.001). Those with lower postoperative FCA had greater increases in serum CTx (ρ = -0.43, p = 0.01). Declines in FCA and BMD were not correlated over the 6 months. In conclusion, FCA decreased dramatically after RYGB, even with most 25OHD levels ≥30 ng/mL and with recommended Ca intake. RYGB patients may need high Ca intake to prevent perturbations in Ca homeostasis, although the approach to Ca supplementation needs further study. Decline in FCA could contribute to the decline in BMD after RYGB, and strategies to avoid long-term skeletal consequences should be investigated.

The American College of Medical Genetics and Genomics (ACMG) recommends that mutations in 56 genes for 24 conditions are clinically actionable and should be reported as secondary findings after whole-genome sequencing (WGS). Our aim was to identify published economic evaluations of detecting mutations in these genes among the general population or among targeted/high-risk populations and conditions and identify gaps in knowledge. A targeted PubMed search from 1994 through November 2014 was performed, and we included original, English-language articles reporting cost-effectiveness or a cost-to-utility ratio or net benefits/benefit-cost focused on screening (not treatment) for conditions and genes listed by the ACMG. Articles were screened, classified as targeting a high-risk or general population, and abstracted by two reviewers. General population studies were evaluated for actual cost-effectiveness measures (e.g., incremental cost-effectiveness ratios (ICER)), whereas studies of targeted populations were evaluated for whether at least one scenario proposed was cost-effective (e.g., ICER of ≤$100,000 per life-year or quality-adjusted life-year gained). A total of 607 studies were identified, and 32 relevant studies were included. Identified studies addressed fewer than one-third (7 of 24; 29%) of the ACMG conditions. The cost-effectiveness of screening in the general population was examined for only 2 of 24 conditions (8%). The cost-effectiveness of most genetic findings that the ACMG recommends for return has not been evaluated in economic studies or in the context of screening in the general population. The individual studies do not directly address the cost-effectiveness of WGS.