Observational studies using propensity score analysis underestimated the effect sizes in critical care medicine

BACKGROUND AND OBJECTIVE

Propensity score (PS) analysis has been increasingly used in critical care medicine; however, its validation has not been systematically investigated. The present study aimed to compare effect sizes in PS-based observational studies vs. randomized controlled trials (RCTs) (or meta-analysis of RCTs).

METHODS

Critical care observational studies using PS were systematically searched in PubMed from inception to April 2013. Identified PS-based studies were matched to one or more RCTs in terms of population, intervention, comparison, and outcome. The effect sizes of experimental treatments were compared for PS-based studies vs. RCTs (or meta-analysis of RCTs) with sign test. Furthermore, ratio of odds ratio (ROR) was calculated from the interaction term of treatment × study type in a logistic regression model. A ROR < 1 indicates greater benefit for experimental treatment in RCTs compared with PS-based studies. RORs of each comparison were pooled by using meta-analytic approach with random-effects model.

RESULTS

A total of 20 PS-based studies were identified and matched to RCTs. Twelve of the 20 comparisons showed greater beneficial effect for experimental treatment in RCTs than that in PS-based studies (sign test P = 0.503). The difference was statistically significant in four comparisons. ROR can be calculated from 13 comparisons, of which four showed significantly greater beneficial effect for experimental treatment in RCTs. The pooled ROR was 0.71 (95% CI: 0.63, 0.79; P = 0.002), suggesting that RCTs (or meta-analysis of RCTs) were more likely to report beneficial effect for the experimental treatment than PS-based studies. The result remained unchanged in sensitivity analysis and meta-regression.

CONCLUSION

In critical care literature, PS-based observational study is likely to report less beneficial effect of experimental treatment compared with RCTs (or meta-analysis of RCTs).

Place of residence and outcomes of patients with heart failure: analysis from the telemonitoring to improve heart failure outcomes trial

BACKGROUND

Recent studies show an association between neighborhood-level measures of socioeconomic status (SES) and outcomes for patients with heart failure. We do not know whether neighborhood SES has a primary effect or is a marker for individual SES.

METHODS AND RESULTS

We used the data from participants of the Telemonitoring to Improve Heart Failure Outcomes (Tele-HF) trial, recruited from 33 US internal medicine and cardiology practices and examined the association between neighborhood SES and outcomes of patients with heart failure. We used census tracts as proxies for neighborhoods and constructed summary SES scores that included information about wealth and income, education, and occupation. The primary end points were readmission and all-cause mortality at 6 months. We conducted patient interviews and medical chart reviews to obtain demographic information, clinical factors, therapies, and individual SES. We included 1557 patients: 524, 516, and 517 from low, medium, and high SES neighborhoods, respectively (mean age, 61.1±15.2 years; 42.2% women).Overall, 745 patients (47.8%) had ≥1 readmission and 179 patients (11.5%) died. When compared with patients in high SES neighborhoods, those living in low-SES neighborhoods were more likely to be readmitted (odds ratio, 1.35; 95% confidence interval, 1.01-1.82), but the mortality rates were not significantly different (odds ratio, 0.78; 95% confidence interval, 0.50-1.18). The results were consistent after multivariable adjustments for individual demographics, clinical factors, and individual SES.

CONCLUSIONS

Among patients with heart failure, neighborhood SES was significantly associated with 6-month all-cause readmission even after adjusting for other patient-level factors, including individual SES. Greater number of events and longer follow-up is required to ascertain the potential effect of neighborhood SES on mortality.

CLINICAL TRIAL REGISTRATION URL

http://clinicaltrials.gov/. Unique identifier: NCT00303212.

Patient and provider perspectives on Bedsider.org, an online contraceptive information tool, in a low income, racially diverse clinic population

OBJECTIVE

To explore patient and provider perspectives regarding a new Web-based contraceptive support tool.

STUDY DESIGN

We conducted a qualitative study at an urban Medicaid-based clinic among sexually active women interested in starting a new contraceptive method, clinic providers and staff. All participants were given the opportunity to explore Bedsider, an online contraceptive support tool developed for sexually active women ages 18-29 by the National Campaign to Prevent Teen and Unplanned Pregnancy and endorsed by the American Congress of Obstetricians and Gynecologists. Focus groups were conducted separately among patient participants and clinic providers/staff using open-ended structured interview guides to identify specific themes and key concepts related to use of this tool in an urban clinic setting.

RESULTS

Patient participants were very receptive to this online contraceptive support tool, describing it as trustworthy, accessible and empowering. In contrast, clinic providers and staff had concerns regarding the Website's legitimacy, accessibility, ability to empower patients and applicability, which limited their willingness to recommend its use to patients.

CONCLUSION

Contrasting opinions regarding Bedsider may point to a potential disconnect between how providers and patients view contraception information tools. Further qualitative and quantitative studies are needed to explore women's perspectives on contraceptive education and counseling and providers' understanding of these perspectives.

IMPLICATIONS STATEMENT

This study identifies a contrast between how patients and providers in an urban clinic setting perceive a Web-based contraceptive tool. Given a potential patient-provider discrepancy in preferred methods and approaches to contraceptive counseling, additional research is needed to enhance this important arena of women's health care.

Syntheses, structures and properties of two 2-D layered hybrid organic-inorganic materials based on different V4O12 building units

Two new layered hybrid organic-inorganic compounds [Zn(pyim)]2V4O12 () (pyim = 2-(2-pyridyl)imidazole) and [Cu(bim)2]2V4O12(H2O)·CH3CH2OH () (bim = bis(1-imidazolyl)methane) based on polyoxovanadates (POVs) and organic ligands decorated transition metal units have been synthesized by hydrothermal and solvothermal methods respectively. Single crystal XRD, fluorescence spectrum, magnetic measurement, IR spectra, powder XRD and thermogravimetric (TG) measurements were performed to analyze the structures and properties of and . The structural analysis reveals that compound features a two-dimensional {[Zn(pyim)]2V4O12}n layered structure, constructed by sine wave-like {V4O12}n(4n-) chains, Zn(2+) ions and pyim ligands. In the layered structure of , {V4O12}(4-) circles are connected by Cu(2+) ions to form {Cu(V4O12)}n(2n-) chains, which are further linked by {Cu(bim)4}(2+) subunits to generate a hybrid layer of . The magnetic susceptibility measurement indicates strong antiferromagnetic interactions between Cu(2+) ions in .

The mutation profile of JAK2 and CALR in Chinese Han patients with Philadelphia chromosome-negative myeloproliferative neoplasms

Mutations in JAK2, MPL and CALR are highly relevant to the Philadelphia chromosome (Ph)-negative myeloproliferative neoplasms (MPNs). We performed high resolution melting analysis and Sanger sequencing together with T-A cloning to elucidate the unique mutation profile of these genes, in Chinese patients with MPNs. Peripheral blood DNA samples were obtained from 80 patients with polycythemia vera (PV), 80 patients with essential thrombocytosis (ET) and 50 patients with primary myelofibrosis (PMF). Ten PV patients were identified with diverse JAK2 exon 12 mutations. Five novel JAK2 Exon 12 mutation patterns (M532V/E543G, N533D, M535I/H538Y/K549I, E543G and D544N) were described. JAK2 V617F was detected in 140 samples (66 PV, 45 ET and 29 PMF). JAK2 Exon 12 mutations were prevalent (13%) and variable in the Chinese patients. Compared with PV patients with JAK2 V617F mutations, PV patients with JAK2 exon 12 mutations had an earlier median onset of disease (P = 0.0013). MPL W515L/K mutations were discerned in 4 ET and 3 PMF patients. Two kinds of CALR mutation, c. 1179_1230del and c. 1234_1235insTTGTC were detected in 20 ET and 16 PMF patients. A novel CALR mutation pattern (c. 1173_1223del/c. 1179_1230del) was identified in 2 PMF samples. In addition, 17 scattered point mutations in CALR c.1153 to c.1255 were also detected in 13 cases with CALR frame-shifting variations and 2 cases without CALR frame-shifting variations. Female patients showed a predisposition to CALR mutations (P = 0.0035). Chinese Ph-negative MPN patients have a unique mutation landscape in the common molecular markers of MPN diagnosis. Validation of the molecular diagnostic pipeline should be emphasized since there is a considerable ethnical diversity in the molecular profiles of Ph-negative MPNs.

Transgenic tobacco plants overexpressing a grass PpEXP1 gene exhibit enhanced tolerance to heat stress

Heat stress is a detrimental abiotic stress limiting the growth of many plant species and is associated with various cellular and physiological damages. Expansins are a family of proteins which are known to play roles in regulating cell wall elongation and expansion, as well as other growth and developmental processes. The in vitro roles of expansins regulating plant heat tolerance are not well understood. The objectives of this study were to isolate and clone an expansin gene in a perennial grass species (Poa pratensis) and to determine whether over-expression of expansin may improve plant heat tolerance. Tobacco (Nicotiana tabacum) was used as the model plant for gene transformation and an expansin gene PpEXP1 from Poa pratensis was cloned. Sequence analysis showed PpEXP1 belonged to α-expansins and was closely related to two expansin genes in other perennial grass species (Festuca pratensis and Agrostis stolonifera) as well as Triticum aestivum, Oryza sativa, and Brachypodium distachyon. Transgenic tobacco plants over-expressing PpEXP1 were generated through Agrobacterium-mediated transformation. Under heat stress (42°C) in growth chambers, transgenic tobacco plants over-expressing the PpEXP1 gene exhibited a less structural damage to cells, lower electrolyte leakage, lower levels of membrane lipid peroxidation, and lower content of hydrogen peroxide, as well as higher chlorophyll content, net photosynthetic rate, relative water content, activity of antioxidant enzyme, and seed germination rates, compared to the wild-type plants. These results demonstrated the positive roles of PpEXP1 in enhancing plant tolerance to heat stress and the possibility of using expansins for genetic modification of cool-season perennial grasses in the development of heat-tolerant germplasm and cultivars.

The genetics of brown coat color and white spotting in domestic yaks (Bos grunniens)

Domestic yaks (Bos grunniens) exhibit two major coat color variations: a brown vs. wild-type black pigmentation and a white spotting vs. wild-type solid color pattern. The genetic basis for these variations in color and distribution remains largely unknown and may be complicated by a breeding history involving hybridization between yaks and cattle. Here, we investigated 92 domestic yaks from China using a candidate gene approach. Sequence variations in MC1R, PMEL and TYRP1 were surveyed in brown yaks; TYRP1 was unassociated with the coloration and excluded. Recessive mutations from MC1R, or p.Gln34*, p.Met73Leu and possibly p.Arg142Pro, are reported in bovids for the first time and accounted for approximately 40% of the brown yaks in this study. The remaining 60% of brown individuals correlated with a cattle-derived deletion mutation from PMEL (p.Leu18del) in a dominant manner. Degrees of white spotting found in yaks vary from color sidedness and white face, to completely white. After examining the candidate gene KIT, we suggest that color-sided and all-white yaks are caused by the serial translations of KIT (Cs6 or Cs29 ) as reported for cattle. The white-faced phenotype in yaks is associated with the KIT haplotype S(wf) . All KIT mutations underlying the serial phenotypes of white spotting in yaks are identical to those in cattle, indicating that cattle are the likely source of white spotting in yaks. Our results reveal the complex genetic origins of domestic yak coat color as either native in yaks through evolution and domestication or as introduced from cattle through interspecific hybridization.

Abstract 106: Association between Insurance Status and Presentation Delay in Young Patients with Acute Myocardial Infarction: Insights from the VIRGO Study

Background: Lacking health insurance and having financial concerns are known barriers to emergency care access in patients with AMI. However we do not know whether being uninsured or underinsured is associated with increased prehospital delay among young adults specifically, and whether this relationship varies by gender.

Methods: We used data from the VIRGO study, a multicenter prospective study of women and men aged 18-55y with AMI (3,572). We excluded non-US patients (587) and those with unknown prehospital delay time (32) or insurance status (2). Participants were divided into 3 groups by health insurance status: 1. uninsured; 2. underinsured (insured but avoided care or medications due to cost concerns); 3. adequately insured (insured and without the above concerns). Prehospital delay was defined as the time interval between symptom onset and hospital presentation. The association between insurance groups and prehospital delay of >12 hours was examined using chi-square test. A hierarchical logistic model was used to evaluate the independent effect of insurance groups on prehospital delay of >12 hours adjusting for site clustering, demographics, medical history and clinical characteristics.

Results: Of the 2951 young individuals with AMI in our study, 1987 were women (67.3%); the median age was 48 (IQR= 44, 52); 38% were underinsured; and 23%, uninsured. While women were less likely than men to be uninsured (21.8 vs 25.4%, P=0.03), they were more likely to be underinsured (60.5 vs 53.6%, P12 hours of prehospital delay: 38% of women and 29% of men (P=0.0001; figure). Insurance status was not associated with delays of >12 hrs in women (P=0.10) or men (P=0.57). After adjustments, the underinsured (OR 0.99; 95%CI 0.81, 1.19) and uninsured (OR 1.11; 95% CI 0.88, 1.39) did not have higher odds of having >12 hrs of prehospital delay compared to the adequately insured.

Conclusion: More than 1 in 3 young individuals with AMI presented to hospitals beyond 12 hours after onset of symptoms. Insurance status was not associated with prehospital delays in this population. Although women are more likely to have >12 hours of prehospital delay, this difference is not attributable to differences in insurance status. Factors beyond the provision of insurance will need to be addressed to reduce delays.

[Possible mechanisms of Roux-en-Y gastric bypass treatment for type 2 diabetes mellitus]

Roux-en-Y gastric bypass(RYGB) is a classic procedure for the treatment of type 2 diabetes mellitus (T2DM), but it remains unclear why this procedure works. There might be several mechanisms that RYGB works through to treat T2DM, including calorie restriction and malabsorption, improvement of insulin resistance and β-cell functions, and altered secretion of gastrointestinal hormones. Altered levels of adipokines and serum bile acids might also play a role after RYGB. Future researches should concentrate on the exact mechanism of the altered hormone levels after RYGB, and whether different methods of gastrointestinal tract reconstruction could lead to various hormone levels.

Abstract 19: Episode of Care Payments Across Two Cardiac Conditions: Where Does the Money Go?

Objective: One approach to reduce health care spending and improve coordination of care is to pay for an episode of care rather than individual services. Anchoring these episodes around an index hospitalization is sensible because hospitalizations are a leading contributor to rising healthcare costs and an index admission provides a clear time to begin the episode. Understanding which care settings are responsible for a greater proportion of expenditures can inform efforts to improve efficiencies in the care provided. Our objectives were to: 1) characterize total episode payments for two conditions and 2) examine the care settings accounting for the highest proportions of the 30-day episode of care payment.

Study Design: We used Medicare Claims data from 2008 and 2009 to identify hospital discharges for acute myocardial infarction (AMI) and heart failure among fee-for-service beneficiaries ≥ 65 years. We defined an episode as admission plus 30 days. To reflect differences in payments due to clinical care rather than geographic or policy adjustments, we omitted or averaged payment adjustments such as wage index and indirect medical education. For hospitalizations involving transfers, we summed the per diem and diagnosis related group payments and attributed this amount to the transfer-out hospital.

Principal Findings: For AMI and heart failure patients respectively, the median unadjusted episode payment was $15,581 (interquartile range (IQR) $11,416, $24,675); and $10,139 (IQR $6,972, $17,827). For AMI, 77% of total payments were for index admission and 23% for post-acute care. Among post-acute care payments, 35% were for readmissions, 30% for skilled nursing facilities (SNF), and 13% for non-acute inpatient stays (i.e., inpatient rehabilitation, inpatient psychiatric facilities, and long-term care facilities). For heart failure, 61% of total payments were for index admission and 37% for post-acute care. Among post-acute care payments for heart failure, 35% were for readmissions, 33% for SNF, and 7% for non-acute inpatient stays.

Conclusions: Total episode payments vary by condition. For heart failure, which does not routinely require procedures, 61% of total episode payments are attributable to the index admissions compared to 77% for AMI. Across both conditions, the highest proportion of payments made after discharge were for readmissions, SNF, and non-acute inpatient stays. These results can inform efforts to reduce costs, including payment reforms such as bundled payment initiatives.

"Phenotyping" hospital value of care for patients with heart failure

OBJECTIVE

To characterize hospitals based on patterns of their combined financial and clinical outcomes for heart failure hospitalizations longitudinally.

DATA SOURCE

Detailed cost and administrative data on hospitalizations for heart failure from 424 hospitals in the 2005-2011 Premier database.

STUDY DESIGN

Using a mixture modeling approach, we identified groups of hospitals with distinct joint trajectories of risk-standardized cost (RSC) per hospitalization and risk-standardized in-hospital mortality rate (RSMR), and assessed hospital characteristics associated with the distinct patterns using multinomial logistic regression.

PRINCIPAL FINDINGS

During 2005-2011, mean hospital RSC decreased from $12,003 to $10,782, while mean hospital RSMR declined from 3.9 to 3.2 percent. We identified five distinct hospital patterns: highest cost and low mortality (3.2 percent of the hospitals), high cost and low mortality (20.4 percent), medium cost and low mortality (34.6 percent), medium cost and high mortality (6.2 percent), and low cost and low mortality (35.6 percent). Longer hospital stay and greater use of intensive care unit and surgical procedures were associated with phenotypes with higher costs or greater mortality.

CONCLUSIONS

Hospitals vary substantially in the joint longitudinal patterns of cost and mortality, suggesting marked difference in value of care. Understanding determinants of the variation will inform strategies for improving the value of hospital care.

A meta-analysis of pemetrexed-based doublet compared with pemetrexed alone for the second-line treatment of advanced non-small-cell lung cancer

PURPOSE

This meta-analysis investigated pemetrexed-based doublet compared with pemetrexed alone as second-line therapy for patients with advanced non-small cell lung cancer.

METHODS

Randomized controlled trials which compared pemetrexed-based doublet with single-agent pemetrexed in patients as second-line treatment of advanced non-small cell lung cancer were searched. Overall survival (OS) was the primary end point, while secondary end points included progression-free survival, overall response rate, 1-year survival rate, and grade 3 or 4 toxicity.

RESULTS

Four eligible randomized clinical trials including 1,084 patients were selected. Meta-analysis demonstrated that pemetrexed-based doublet arm significantly improved the overall response rate (OR=2.70, 95% CI: 1.76-4.15, p=0.000), compared with docetaxel alone group, while there were no significant differences in overall survival (HR=0.88, 95% CI: 0.74-1.04, p=0.132), progression-free survival (HR=0.91, 95% CI: 0.73-1.15, p=0.443), and 1-year survival rate (OR=1.43, 95% CI: 0.85-2.40, p=0.178) between the two arms. However, there were more frequencies of grade 3-4 leucopenia (OR=2.86, 95% CI: 1.32-6.20, p=0.008), neutropenia (OR=2.69, 95% CI: 1.55-4.68, p=0.000) and thrombocytopenia (OR=6.92, 95% CI: 2.51-19.07, p=0.000) in pemetrexed-based doublet group. Grade 3-4 anemia (OR=0.62, 95% CI: 0.33-1.18, p=0.144) and fatigue (OR=1.15, 95% CI: 0.73-1.79, p=0.550) had equivalent incidences in the two groups.

CONCLUSIONS

This is the first meta-analysis to compare pemetrexed-based doublet with single-agent pemetrexed in second-line therapy of non-small cell lung cancer. Our meta-analysis suggested that pemetrexed combination chemotherapy was not superior to single-agent arm and was not recommended as the second-line chemotherapy for patients with non-small cell lung cancer (Tab. 2, Fig. 6, Ref. 20).

On the roles of graphene oxide doping for enhanced supercurrent in MgB2 based superconductors

Due to their graphene-like properties after oxygen reduction, incorporation of graphene oxide (GO) sheets into correlated-electron materials offers a new pathway for tailoring their properties. Fabricating GO nanocomposites with polycrystalline MgB2 superconductors leads to an order of magnitude enhancement of the supercurrent at 5 K/8 T and 20 K/4 T. Herein, we introduce a novel experimental approach to overcome the formidable challenge of performing quantitative microscopy and microanalysis of such composites, so as to unveil how GO doping influences the structure and hence the material properties. Atom probe microscopy and electron microscopy were used to directly image the GO within the MgB2, and we combined these data with computational simulations to derive the property-enhancing mechanisms. Our results reveal synergetic effects of GO, namely, via localized atomic (carbon and oxygen) doping as well as texturing of the crystals, which provide both inter- and intra-granular flux pinning. This study opens up new insights into how low-dimensional nanostructures can be integrated into composites to modify the overall properties, using a methodology amenable to a wide range of applications.

Modification and evaluation of Brucella broth based Campylobacter jejuni transport medium

Reliable transport of Campylobacter jejuni isolates is critical to microbial epidemiology research, especially in developing countries without a good temperature control mailing system. Various factors, including oxygen, temperature, transport medium composition, could affect the survival of C. jejuni. In this study, the protective effects of different ingredients in C. jejuni transport media at 4 °C and 25 °C and under aerobic condition were quantitatively evaluated respectively. The results showed that enriched medium, supplementation with 5% blood and being kept at 4 °C could improve the viability of different C. jejuni strains during transport. In addition, supplementation with 25 mmol/L L-fucose in Wang's transport medium could significantly improve the survival of C. jejuni at both 4 °C and 25 °C. To the best of our knowledge, this is the first report to evaluate the protective effect of L-fucose in enriched C. jejuni transport medium which is feasible in developing countries without an effective cold chain mailing system. These data will be good reference for C. jejuni transport medium improvement in future.

Crosstalk between miR-34a and Notch Signaling Promotes Differentiation in Apical Papilla Stem Cells (SCAPs)

Stem cells from the apical papilla (SCAPs) are important for the formation and regeneration of root dentin. Here, we examined the expression of Notch signaling components in SCAPs and investigated crosstalk between microRNA miR-34aand Notch signaling during cell differentiation. We found that human SCAPs express NOTCH2, NOTCH3, JAG2, DLL3, and HES1, and we tested the relationship between Notch signaling and both cell differentiation and miR-34a expression. NOTCH activation in SCAPs inhibited cell differentiation and up-regulated the expression of miR-34a, whereas miR-34a inhibited Notch signaling in SCAPs by directly targeting the 3'UTR of NOTCH2 and HES1 mRNA and suppressing the expression of NOTCH2, N2ICD, and HES1. DSPP, RUNX2, OSX, and OCN expression was consequently up-regulated. Thus, Notch signaling in human SCAPs plays a vital role in maintenance of these cells. miR-34a interacts with Notch signaling and promotes both odontogenic and osteogenic differentiation of SCAPs.