Judith Anzures-Cabrera

Meta-analysis of skewed data: Combining results reported on log-transformed or raw scales

When literature-based meta-analyses involve outcomes with skewed distributions, the best available data can sometimes be a mixture of results presented on the raw scale and results presented on the logarithmic scale. We review and develop methods for transforming between these results for two-group studies, such as clinical trials and prospective or cross-sectional epidemiological studies. These allow meta-analyses to be conducted using all studies and on a common scale. The methods can also be used to produce a meta-analysis of ratios of geometric means when skewed data are reported on the raw scale for every study. We compare three methods, two of which have alternative standard error formulae, in an application and in a series of simulation studies. We conclude that an approach based on a log-normal assumption for the raw data is reasonably robust to different true distributions; and we provide new standard error approximations for this method. An assumption can be made that the standard deviations in the two groups are equal. This increases precision of the estimates, but if incorrect can lead to very misleading results. Copyright

The effect of cholesteryl ester transfer protein inhibition on lipids, lipoproteins, and markers of HDL function after an acute coronary syndrome: the dal-ACUTE randomized trial

AIMS The effects of cholesteryl ester transfer protein (CETP) inhibition on lipids, inflammation, and markers of high-density lipoprotein (HDL) function, following an acute coronary syndrome (ACS), are unknown. METHODS AND RESULTS The dal-ACUTE study randomized 300 patients (1 : 1) to dalcetrapib 600 mg/day or placebo within 1 week of an ACS. The primary endpoint was per cent change in HDL-cholesterol (HDL-C) after 4 weeks. Secondary endpoints included apolipoprotein levels, markers of HDL function, and inflammation. Dalcetrapib treatment increased HDL-C and apolipoprotein A1 by 33.7 and 11.8%, respectively (both P < 0.001) and total cholesterol efflux by 9.5% (P = 0.003) after 4 weeks, principally via an increase in non-ATP-binding cassette transporter (ABC) A1-mediated efflux, without statistically significant changes in pre-β1-HDL levels. The increase in total efflux with dalcetrapib correlated most strongly with increases in apolipoprotein A1 and HDL-C (r = 0.46 and 0.43, respectively) rather than the increase in pre-β1-HDL (r = 0.32). Baseline and on-treatment ABCA1-mediated efflux correlated most strongly with pre-β1-HDL levels; in contrast, non-ABCA1-mediated efflux correlated better with apolipoprotein A1 and HDL-C levels. CONCLUSIONS High-density lipoprotein raised through CETP inhibition with dalcetrapib improves cholesterol efflux, principally via a non-ABCA1-mediated pathway. While HDL-C was increased by one-third, apolipoprotein A1 and total efflux were increased only by one-tenth, supporting the concept of dissociation between improvements in HDL function and HDL-C levels, which may be of relevance to ongoing trials and the development of therapeutic interventions targeting HDL.

A tool to assess the quality of a meta-analysis

BACKGROUND Because meta-analyses are increasingly prevalent and cited in the medical literature, it is important that tools are available to assess their methodological quality. When performing an empirical study of the quality of published meta-analyses, we found that existing tools did not place a strong emphasis on statistical and interpretational issues. METHODS We developed a quality-assessment tool using existing materials and expert judgment as a starting point, followed by multiple iterations of input from our working group, piloting, and discussion. After having used the tool for our empirical study, agreement for four key items in the tool was measured using weighted kappa coefficients. RESULTS Our tool contained 43 items divided into four key areas (data sources, analysis of individual studies, meta-analysis methods, and interpretation), and each area ended with a summary question. We also produced guidance for completing the tool. Agreement between raters was fair to moderate. CONCLUSIONS The tool should usefully inform subsequent initiatives to develop quality-assessment tools for meta-analysis. We advocate use of consensus between independent raters when assessing statistical appropriateness and adequacy of interpretation in meta-analyses.

Safety, Tolerability and Pharmacokinetics of Dalcetrapib Following Single and Multiple Ascending Doses in Healthy Subjects

AbstractBackground: Dalcetrapib is a modulator of cholesteryl ester transfer protein (CETP) activity developed to raise levels of high-density lipoprotein cholesterol (HDL-C) with the goal of further reduction of cardiovascular events additive to standard of care alone. In clinical studies, dalcetrapib has been shown to effectively increase levels of HDL-C with no significant safety concerns. Objective: The primary objective was to investigate the safety of single ascending and multiple ascending doses of dalcetrapib at doses markedly greater than that intended therapeutically (600 mg/day). Secondary objectives were to investigate the pharmacokinetics/pharmacodynamics and dose proportionality of dalcetrapib. Study Design: Randomized, double-blind, placebo-controlled, combined single and multiple ascending dose phase I study. Healthy males (age 18–65 years, body mass index 18–?2) were randomized to four of five dalcetrapib doses (2100,2700, 3300, 3900 or 4500 mg) or placebo, with ≥10 days washout between doses (n= 15, single ascending doses) or to dalcetrapib (1800, 2100, 3000 or 3900 mg once daily) or placebo for 7 days (four cohorts, each n= 10, randomization 8:2, multiple ascending doses). Main Outcome Measure: Tolerability and safety were assessed by monitoring adverse events (AEs), laboratory parameters, vital signs and 12-lead ECG recordings. Primary pharmacokinetic assessments were area under the plasma concentration-time curve (AUC) from time zero to infinity (AUC∞) and maximum observed plasma concentration (Cmax) [single doses] and AUC from time zero to 24 hours (AUC24) and Cmax (multiple doses). Pharmacodynamic assessments included CETP activity and lipids (multiple dosing only). Results: Exposure increased with dose but was less than proportional to increasing dose after single dosing, although deviation from dose proportionality could not be demonstrated for Cmax. Dose proportionality was consistent following multiple doses. Steady state was modelled to have been reached by approximately 4 days, with little to no accumulation. CETP activity reduction was dose dependent (maximum −55% after 3900 mg; placebo −2.6%) at 6 hours post-dose on day 1, while HDL-C increased by 12–19% (placebo −13%) on day 8 following treatment with 1800−3900 mg/day for 7 days. All AEs were mild or moderate in intensity and there were no serious AEs, deaths or withdrawals due to AEs. No clinically relevant effects on laboratory parameters, cardiac parameters or vital signs were noted. Conclusion: Single-dose dalcetrapib up to 4500 mg and multiple doses up to 3900 mg were generally safe and well tolerated.

Safety, tolerability and pharmacokinetics of dalcetrapib following single and multiple ascending doses in healthy subjects: a randomized, double-blind, placebo-controlled, phase I study.

BACKGROUND Dalcetrapib is a modulator of cholesteryl ester transfer protein (CETP) activity developed to raise levels of high-density lipoprotein cholesterol (HDL-C) with the goal of further reduction of cardiovascular events additive to standard of care alone. In clinical studies, dalcetrapib has been shown to effectively increase levels of HDL-C with no significant safety concerns. OBJECTIVE The primary objective was to investigate the safety of single ascending and multiple ascending doses of dalcetrapib at doses markedly greater than that intended therapeutically (600 mg/day). Secondary objectives were to investigate the pharmacokinetics/pharmacodynamics and dose proportionality of dalcetrapib. STUDY DESIGN Randomized, double-blind, placebo-controlled, combined single and multiple ascending dose phase I study. Healthy males (age 18-65 years, body mass index 18-32 kg/m2) were randomized to four of five dalcetrapib doses (2100, 2700, 3300, 3900 or 4500 mg) or placebo, with ≥10 days washout between doses (n = 15, single ascending doses) or to dalcetrapib (1800, 2100, 3000 or 3900 mg once daily) or placebo for 7 days (four cohorts, each n = 10, randomization 8 : 2, multiple ascending doses). MAIN OUTCOME MEASURE Tolerability and safety were assessed by monitoring adverse events (AEs), laboratory parameters, vital signs and 12-lead ECG recordings. Primary pharmacokinetic assessments were area under the plasma concentration-time curve (AUC) from time zero to infinity (AUC(∞)) and maximum observed plasma concentration (C(max)) [single doses] and AUC from time zero to 24 hours (AUC(24)) and C(max) (multiple doses). Pharmacodynamic assessments included CETP activity and lipids (multiple dosing only). RESULTS Exposure increased with dose but was less than proportional to increasing dose after single dosing, although deviation from dose proportionality could not be demonstrated for C(max). Dose proportionality was consistent following multiple doses. Steady state was modelled to have been reached by approximately 4 days, with little to no accumulation. CETP activity reduction was dose dependent (maximum -55% after 3900 mg; placebo -2.6%) at 6 hours post-dose on day 1, while HDL-C increased by 12-19% (placebo -13%) on day 8 following treatment with 1800-3900 mg/day for 7 days. All AEs were mild or moderate in intensity and there were no serious AEs, deaths or withdrawals due to AEs. No clinically relevant effects on laboratory parameters, cardiac parameters or vital signs were noted. CONCLUSION Single-dose dalcetrapib up to 4500 mg and multiple doses up to 3900 mg were generally safe and well tolerated.

No clinically relevant drug-drug interactions when dalcetrapib is co-administered with a monophasic oral contraceptive (Microgynon® 30).

UNLABELLED Dalcetrapib, a cholesteryl ester transfer protein modulator, under development to increase high-density lipoprotein cholesterol and potentially decrease cardiovascular risk, will potentially be co-prescribed to women on oral contraceptive (OC). OBJECTIVE Assess the effect of dalcetrapib on the pharmacokinetics and ability to suppress ovulation of Microgynon® 30, a representative monophasic OC. MATERIALS AND METHODS A single-center, randomized, open-label, two-period crossover study in healthy women receiving monophasic OC. Subjects received Microgynon® 30 (ethinylestradiol 0.03 mg/levonorgestrel 0.15 mg) once daily for 21 days followed by 7 treatment-free days (run-in period), then were randomized to Microgynon® 30 daily for 21 days with or without dalcetrapib 900 mg daily for Day 1 - 14. Plasma ethinylestradiol and levonorgestrel were measured on Day 14, and luteinizing hormone, follicle stimulating hormone, progesterone and estrogen from Day 11 - 14. The primary endpoint plasma exposure (AUC0-24 and Cmax) on Day 14 was evaluated for ethinylestradiol and levonorgestrel. Safety was monitored throughout. RESULTS 30 subjects were randomized. The exposure of ethinylestradiol and levonorgestrel was similar when Microgynon® 30 was administered with or without dalcetrapib; for ethinylestradiol the geometric mean ratio %, (90% confidence interval (CI)) for AUC0-24 and Cmax were 92 (86 - 98) and 105 (95 - 115) and for levonorgestrel 92 (88 - 96) and 93 (87 - 99), respectively. Concentrations of luteinizing hormone, follicle stimulating hormone, estrogen and progesterone were comparable between treatments. CONCLUSIONS Dalcetrapib has no clinically relevant effect on the pharmacokinetics of ethinylestradiol and levonorgestrel. Contraceptive efficacy of Microgynon® 30 is not anticipated to be compromised by co-administration of dalcetrapib.

Efficacy and safety of lebrikizumab in adult patients with mild-to-moderate asthma not receiving inhaled corticosteroids

BACKGROUND Asthma is a heterogeneous and complex disease in both its clinical course and response to treatment. IL-13 is central to Type 2 inflammation and contributes to many features of asthma. In a previous Phase 2 study, lebrikizumab, an anti-IL-13 monoclonal antibody, did not significantly improve FEV1 in mild-to-moderate asthma patients not receiving ICS therapy. This Phase 3 study was designed to further assess the efficacy and safety of lebrikizumab in adult patients with mild-to-moderate asthma treated with daily short-acting β2-agonist therapy alone. METHODS Adult patients with mild-to-moderate asthma were randomised to receive lebrikizumab 125 mg subcutaneously (SC), placebo SC, or montelukast 10 mg orally for 12 weeks, with an 8-week follow-up period. The primary efficacy endpoint was absolute change in pre-bronchodilator FEV1 from baseline at Week 12. FINDINGS A total of 310 patients were randomised and dosed in the study. The mean absolute change in FEV1 from baseline at Week 12 was higher in the lebrikizumab-treated arm compared with placebo (150 mL versus 67 mL); however, this improvement did not achieve statistical significance (overall adjusted difference of 83 mL [95% CI: -3, 170]; p = .06). Montelukast did not improve FEV1 as compared with placebo. Lebrikizumab was generally safe and well tolerated during the study. INTERPRETATION Lebrikizumab did not significantly improve FEV1 in mild-to-moderate asthma patients at a dose expected to inhibit the IL-13 pathway. Inhibiting IL-13 in this patient population was not sufficient to improve lung function. These data support the findings of a previous trial of lebrikizumab in patients not receiving ICS. CLINICAL TRIALS REGISTRY NUMBER This trial was registered under NCT02104674 at http://www.clinicaltrials.gov.

Methodological quality of meta-analyses : matched-pairs comparison over time and between industry sponsored and academic-sponsored reports

CONTEXT Meta-analyses are regularly used to inform healthcare decisions. Concerns have been expressed about the quality of meta-analyses and, in particular, about those supported by the pharmaceutical industry. OBJECTIVE The objective of this study is to compare the quality of pharmaceutical-industry-supported meta-analyses with academic meta-analyses and of meta-analyses published before and after companies started to disclose their data. DATA SOURCES We identified industry-supported meta-analyses by searching the Scopus bibliographic database, using author affiliations. We matched each industry-supported meta-analysis with an academic meta-analysis using high-level MeSH terms in PubMed. STUDY SELECTION We included meta-analyses of randomized trials assessing the efficacy or safety of any pharmaceutical intervention in humans, published in 2002-2004 or 2008-2009. Cochrane reviews were excluded. Two individuals independently selected papers, with discrepancies resolved by two further individuals. ASSESSMENT We developed and piloted a quality-assessment tool, consisting of 43 questions in four domains, with a key summary question covering each domain. Two individuals independently assessed each meta-analysis. RESULTS We examined 126 meta-analysis publications in 63 matched pairs. The average quality was low, with fewer than 50% adequate in three of the four domains. Industry-supported meta-analyses less often demonstrated adequate methods for locating studies and assessing their quality (odds ratio 0.44, 95% confidence interval 0.21 to 0.92), for analysing the included studies (0.52, 0.25 to 1.06), for undertaking meta-analyses (0.82, 0.40 to 1.68) and in reaching sound conclusions (0.62, 0.30 to 1.28). Quality generally improved over time, particularly for some aspects of industry reports. CONCLUSIONS Academic meta-analysis papers are generally of higher quality than industry-supported ones. This is largely due to less detailed reporting in industry-supported meta-analyses and a tendency for them to take the included studies at face value, probably arising from the implicit assumption that these studies already have high methodological standards to meet licensing requirements. The improved quality over time does not appear to be due to the use of data disclosed by industry. The main limitations of this study are the small sample of papers and the subjective nature of some of the assessment processes.

Graphics for Meta-Analysis

We present 4 types of graphic used in meta-analysis. The commonest is the forest plot, and we discuss important aspects of the basic form of this plot. We present 2 enhanced versions, one displaying the results of subgroup analysis, and the second displaying absolute risks alongside relative risks from a meta-analysis of a binary outcome. The funnel plot is a well-established graph for assessing publication bias. We show some alternative forms, including a recently suggested enhancement using contours. The third type is a bubble plot used to summarize the results of meta-regression. Finally, we show a graphic designed for network meta-analysis, presenting rankings of the treatments that are compared. We prepared programs and graphs using GenStat™, R, RevMan™, SAS™ and Stata™, and these are available from the website.