Meta-analysis by combining p-values: simulated linkage studies

Meta-analysis has been little explored to make an overall assessment of linkage from different studies. In practice, it is likely that published linkage studies will only report p-values. We compared the performance of the widely used Fisher method for combining p-values with that of pooling raw data. More loci were consistently found by pooling raw data. In the absence of further information, combining p-values can provide an overall, but limited, assessment of different linkage studies. However, meta-analysis would be better viewed as a preliminary step toward the goal of analyzing the pooled raw data.     

Governance challenges for managed care organizations. Interview by Ann C. Bartling

When Healthcare Executive asked managed care organization CEOs and board chairs to identify governance challenges, they found the question so easy that it was difficult to limit their responses. while all the healthcare leaders interviewed pointed to the need to--and challenge of--staying ahead of the changes affecting the healthcare field, many identified challenges that were more specific to their organizations, markets, or patient population. Some also pointed out that while their challenges may be shared by hospitals and other provider organizations, there were aspects of each that were particularly relevant to managed care organizations, which often offer a variety of products in a number of different of markets.     

Evidence that parent‐of‐origin affects birth‐weight reductions at high altitude

Hypoxia exerts a profound depressant effect on fetal growth, lowering birth weight, and raising mortality risk. Multigenerational high‐altitude populations are relatively protected from this birth‐weight decline, leading us to hypothesize that genetic factors were involved. We asked if the amount of high‐ versus low‐altitude ancestry influenced birth weight at high altitude and, specifically, whether such influences were affected by parent‐of‐origin effects (i.e., genomic imprinting). Medical records were reviewed from 1,343 consecutive, singleton deliveries in La Paz, Bolivia (3,600 m) of high‐ (Andean) or low‐ (European) altitude ancestry. Parental surnames were used to classify ancestry as Andean, European, Mestizo (“mixed”) or some combination thereof. The effects of population ancestry on birth weight were determined by categorical, conditional linear regression. Babies born at altitude with two Andean parents weighed 252 g more than their European counterparts, with the protective effect being proportional to the amount of Andean parentage and independent of maternal parity, body size, smoking, or socioeconomic status. Paternal compared with maternal transmission raised birth weight 81 g for a given ancestry group. We concluded that indigenous high‐altitude ancestry protected against hypoxia‐associated fetal growth reduction in a dose‐dependent fashion consistent with the involvement of genetic factors. Further, some of the genes involved appeared to be influenced by parent‐of‐origin effects, given that maternal transmission restricted and paternal transmission enhanced fetal growth. Am. J. Hum. Biol., 2008. © 2008 Wiley‐Liss, Inc.     

Ranibizumab as an adjunct to laser for macular edema secondary to branch retinal vein occlusion

Purpose:

To compare the safety, efficacy, and dosing regimen of intravitreal ranibizumab as an adjunct to laser therapy for the treatment of macular edema secondary to branch retinal vein occlusion (BRVO).

Materials and Methods:

Thirty eyes of 30 patients of BRVO of at least 6 weeks duration were randomized into three groups: Group 1 received grid laser treatment alone, Group 2 received a single dose of intravitreal injection of ranibizumab (0.5 mg / 0.05 ml) followed by grid laser treatment on 7^th day following injection, while Group 3 received three loading doses of intravitreal ranibizumab at monthly interval (i.e. 0, 1, & 2 months) + standard laser treatment 7 days after the 1^st injection. Outcome measure noted at 6 months follow-up were the improvement in best-corrected visual acuity (BCVA) and central macular thickness (CMT).

Results:

At 6 months follow-up, there was an average gain of 12 letters (P=0.05), 17.5 letters (P=0.05) and 19 letters (P=0.05) in groups 1, 2, and 3, respectively, with the decrease in CMT being 208.7 μm (P=0.05), 312.9 μm (P= 0.05) and 326.8 μm (P=0.05), respectively, in these groups. Gain in BCVA of more than 3 lines was noted in 1/10 patients in Group 1(10%) as compared to 3/10 (30%) and 4/10 (40%) patients in groups 2 and 3, respectively.

Conclusion:

The gain in BCVA and reduction in CMT were better with combination therapy (single- and triple- dose regimen) compared to grid laser alone. Single dose of intravitreal ranibizumab with grid laser seems to be an effective therapy.