Correction to: To develop a regional ICU mortality prediction model during the first 24 h of ICU admission utilizing MODS and NEMS with six other independent variables from the critical care information system (CCIS) Ontario, Canada.

[This corrects the article DOI: 10.1186/s40560-016-0143-6.].

On the estimation of intracluster correlation for time-to-event outcomes in cluster randomized trials.

Cluster randomized trials (CRTs) involve the random assignment of intact social units rather than independent subjects to intervention groups. Time-to-event outcomes often are endpoints in CRTs. Analyses of such data need to account for the correlation among cluster members. The intracluster correlation coefficient (ICC) is used to assess the similarity among binary and continuous outcomes that belong to the same cluster. However, estimating the ICC in CRTs with time-to-event outcomes is a challenge because of the presence of censored observations. The literature suggests that the ICC may be estimated using either censoring indicators or observed event times. A simulation study explores the effect of administrative censoring on estimating the ICC. Results show that ICC estimators derived from censoring indicators or observed event times are negatively biased. Analytic work further supports these results. Observed event times are preferred to estimate the ICC under minimum frequency of administrative censoring. To our knowledge, the existing literature provides no practical guidance on the estimation of ICC when substantial amount of administrative censoring is present. The results from this study corroborate the need for further methodological research on estimating the ICC for correlated time-to-event outcomes. Copyright © 2016 John Wiley & Sons, Ltd.

To develop a regional ICU mortality prediction model during the first 24 h of ICU admission utilizing MODS and NEMS with six other independent variables from the Critical Care Information System (CCIS) Ontario, Canada.

BACKGROUND: Intensive care unit (ICU) scoring systems or prediction models evolved to meet the desire of clinical and administrative leaders to assess the quality of care provided by their ICUs. The Critical Care Information System (CCIS) is province-wide data information for all Ontario, Canada level 3 and level 2 ICUs collected for this purpose. With the dataset, we developed a multivariable logistic regression ICU mortality prediction model during the first 24 h of ICU admission utilizing the explanatory variables including the two validated scores, Multiple Organs Dysfunctional Score (MODS) and Nine Equivalents Nursing Manpower Use Score (NEMS) followed by the variables age, sex, readmission to the ICU during the same hospital stay, admission diagnosis, source of admission, and the modified Charlson Co-morbidity Index (CCI) collected through the hospital health records. METHODS: This study is a single-center retrospective cohort review of 8822 records from the Critical Care Trauma Centre (CCTC) and Medical-Surgical Intensive Care Unit (MSICU) of London Health Sciences Centre (LHSC), Ontario, Canada between 1 Jan 2009 to 30 Nov 2012. Multivariable logistic regression on training dataset (n = 4321) was used to develop the model and validate by bootstrapping method on the testing dataset (n = 4501). Discrimination, calibration, and overall model performance were also assessed. RESULTS: The predictors significantly associated with ICU mortality included: age (p < 0.001), source of admission (p < 0.0001), ICU admitting diagnosis (p < 0.0001), MODS (p < 0.0001), and NEMS (p < 0.0001). The variables sex and modified CCI were not significantly associated with ICU mortality. The training dataset for the developed model has good discriminating ability between patients with high risk and those with low risk of mortality (c-statistic 0.787). The Hosmer and Lemeshow goodness-of-fit test has a strong correlation between the observed and expected ICU mortality (χ (2) = 5.48; p > 0.31). The overall optimism of the estimation between the training and testing data set ΔAUC = 0.003, indicating a stable prediction model. CONCLUSIONS: This study demonstrates that CCIS data available after the first 24 h of ICU admission at LHSC can be used to create a robust mortality prediction model with acceptable fit statistic and internal validity for valid benchmarking and monitoring ICU performance.

A comparison of confidence interval methods for the intraclass correlation coefficient in community-based cluster randomization trials with a binary outcome.

BACKGROUND: Many investigators rely on previously published point estimates of the intraclass correlation coefficient rather than on their associated confidence intervals to determine the required size of a newly planned cluster randomized trial. Although confidence interval methods for the intraclass correlation coefficient that can be applied to community-based trials have been developed for a continuous outcome variable, fewer methods exist for a binary outcome variable. The aim of this study is to evaluate confidence interval methods for the intraclass correlation coefficient applied to binary outcomes in community intervention trials enrolling a small number of large clusters. Existing methods for confidence interval construction are examined and compared to a new ad hoc approach based on dividing clusters into a large number of smaller sub-clusters and subsequently applying existing methods to the resulting data. METHODS: Monte Carlo simulation is used to assess the width and coverage of confidence intervals for the intraclass correlation coefficient based on Smith's large sample approximation of the standard error of the one-way analysis of variance estimator, an inverted modified Wald test for the Fleiss-Cuzick estimator, and intervals constructed using a bootstrap-t applied to a variance-stabilizing transformation of the intraclass correlation coefficient estimate. In addition, a new approach is applied in which clusters are randomly divided into a large number of smaller sub-clusters with the same methods applied to these data (with the exception of the bootstrap-t interval, which assumes large cluster sizes). These methods are also applied to a cluster randomized trial on adolescent tobacco use for illustration. RESULTS: When applied to a binary outcome variable in a small number of large clusters, existing confidence interval methods for the intraclass correlation coefficient provide poor coverage. However, confidence intervals constructed using the new approach combined with Smith's method provide nominal or close to nominal coverage when the intraclass correlation coefficient is small (<0.05), as is the case in most community intervention trials. CONCLUSION: This study concludes that when a binary outcome variable is measured in a small number of large clusters, confidence intervals for the intraclass correlation coefficient may be constructed by dividing existing clusters into sub-clusters (e.g. groups of 5) and using Smith's method. The resulting confidence intervals provide nominal or close to nominal coverage across a wide range of parameters when the intraclass correlation coefficient is small (<0.05). Application of this method should provide investigators with a better understanding of the uncertainty associated with a point estimator of the intraclass correlation coefficient used for determining the sample size needed for a newly designed community-based trial.

Reliability among central readers in the evaluation of endoscopic findings from patients with Crohn's disease.

OBJECTIVE: The Crohn's Disease Endoscopic Index of Severity (CDEIS) and Simple Endoscopic Score for Crohn's Disease (SES-CD) are commonly used to assess Crohn's disease (CD) activity; however, neither instrument has been fully validated. We assessed intra-rater and inter-rater reliability of these indices. DESIGN: Video recordings of colonoscopies obtained from 50 patients with CD who participated in an induction trial of a biological therapy were triplicated and reviewed in random order by four central readers. Data were used to assess intra-rater and inter-rater reliability for CDEIS, SES-CD and a global evaluation of lesion severity (GELS). Subsequently, readers participated in a consensus process that identified common sources of disagreement. RESULTS: Intraclass correlation coefficients (ICCs) for intra-rater reliability for CDEIS, SES-CD and GELS (95% CIs) were 0.89 (0.86 to 0.93), 0.91 (0.89 to 0.95) and 0.81 (0.77 to 0.89), respectively, with standard error of measurement (SEM) of 2.10, 2.42 and 1.15. The corresponding ICCs for inter-rater reliability were 0.71 (0.63 to 0.76), 0.83 (0.75 to 0.88) and 0.62 (0.52 to 0.70), with SEM of 3.42, 3.07 and 1.63, respectively. Correlation between CDEIS and GELS was 0.75, between SES-CD and GELS was 0.74 and between CDEIS and SES-CD was 0.92. The most common sources of disagreement were interpretation of superficial ulceration, definition of disease site at the ileocolonic anastomosis, assessment of anorectal lesions and grading severity of stenosis. CONCLUSIONS: Central reading of CDEIS and SES-CD had 'substantial' to 'almost perfect' intra-rater and inter-rater reliability; however, the responsiveness of these instruments is yet to be determined. TRIAL REGISTRATION NUMBER: Clinicaltrials.gov NCT01466374.

Adjusted inference procedures for the interobserver agreement in twin studies.

We propose adjusted inference procedures for evaluating the agreement/disagreement of two raters in a clustered setting involving twins or paired body parts. These procedures include the construction of a confidence interval for the kappa statistic, a related test of statistical significance and a formula that facilitates sample size estimation. The results of a simulation study suggest that a simple adjustment using an estimated design effect will provide valid inferences. The methods proposed are illustrated using an example from the literature.

Early combined immunosuppression for the management of Crohn's disease (REACT): a cluster randomised controlled trial.

BACKGROUND: Conventional management of Crohn's disease features incremental use of therapies. However, early combined immunosuppression (ECI), with a TNF antagonist and antimetabolite might be a more effective strategy. We compared the efficacy of ECI with that of conventional management for treatment of Crohn's disease. METHODS: In this open-label cluster randomised controlled trial (Randomised Evaluation of an Algorithm for Crohn's Treatment, REACT), we included community gastroenterology practices from Belgium and Canada that were willing to be assigned to either of the study groups, participate in all aspects of the study, and provide data on up to 60 patients with Crohn's disease. These practices were randomly assigned (1:1) to either ECI or conventional management. The computer-generated randomisation was minimised by country and practice size. Up to 60 consecutive adult patients were assessed within practices. Patients who were aged 18 years or older; documented to have Crohn's disease; able to speak or understand English, French, or Dutch; able to access a telephone; and able to provide written informed consent were followed up for 2 years. The primary outcome was the proportion of patients in corticosteroid-free remission (Harvey-Bradshaw Index score ≤ 4) at 12 months at the practice level. This trial is registered with ClinicalTrials.gov, number NCT01030809. FINDINGS: This study took place between March 15, 2010, and Oct 1, 2013. Of the 60 practices screened, 41 were randomly assigned to either ECI (n=22) or conventional management (n=19). Two practices (one in each group) discontinued because of insufficient resources. 921 (85%) of the 1084 patients at ECI practices and 806 (90%) of 898 patients at conventional management practices completed 12 months follow-up and were included in an intention-to-treat analysis. The 12 month practice-level remission rates were similar at ECI and conventional management practices (66·0% [SD 14·0] and 61·9% [16·9]; adjusted difference 2·5%, 95% CI -5·2% to 10·2%, p=0·5169). The 24 month patient-level composite rate of major adverse outcomes defined as occurrence of surgery, hospital admission, or serious disease-related complications was lower at ECI practices than at conventional management practices (27·7% and 35·1%, absolute difference [AD] 7·3%, hazard ratio [HR]: 0·73, 95% CI 0·62 to 0·86, p=0·0003). There were no differences in serious drug-related adverse events. INTERPRETATION: Although ECI was not more effective than conventional management for controlling Crohn's disease symptoms, the risk of major adverse outcomes was lower. The latter finding should be considered hypothesis-generating for future trials. ECI was not associated with an increased risk of serious drug-related adverse events or mortality. FUNDING: AbbVie Pharmaceuticals.

Propensity score methods for estimating relative risks in cluster randomized trials with low-incidence binary outcomes and selection bias.

Despite randomization, selection bias may occur in cluster randomized trials. Classical multivariable regression usually allows for adjusting treatment effect estimates with unbalanced covariates. However, for binary outcomes with low incidence, such a method may fail because of separation problems. This simulation study focused on the performance of propensity score (PS)-based methods to estimate relative risks from cluster randomized trials with binary outcomes with low incidence. The results suggested that among the different approaches used (multivariable regression, direct adjustment on PS, inverse weighting on PS, and stratification on PS), only direct adjustment on the PS fully corrected the bias and moreover had the best statistical properties.

Early palliative care for patients with advanced cancer: a cluster-randomised controlled trial.

BACKGROUND: Patients with advanced cancer have reduced quality of life, which tends to worsen towards the end of life. We assessed the effect of early palliative care in patients with advanced cancer on several aspects of quality of life. METHODS: The study took place at the Princess Margaret Cancer Centre (Toronto, ON, Canada), between Dec 1, 2006, and Feb 28, 2011. 24 medical oncology clinics were cluster randomised (in a 1:1 ratio, using a computer-generated sequence, stratified by clinic size and tumour site [four lung, eight gastrointestinal, four genitourinary, six breast, two gynaecological]), to consultation and follow-up (at least monthly) by a palliative care team or to standard cancer care. Complete masking of interventions was not possible; however, patients provided written informed consent to participate in their own study group, without being informed of the existence of another group. Eligible patients had advanced cancer, European Cooperative Oncology Group performance status of 0-2, and a clinical prognosis of 6-24 months. Quality of life (Functional Assessment of Chronic Illness Therapy--Spiritual Well-Being [FACIT-Sp] scale and Quality of Life at the End of Life [QUAL-E] scale), symptom severity (Edmonton Symptom Assessment System [ESAS]), satisfaction with care (FAMCARE-P16), and problems with medical interactions (Cancer Rehabilitation Evaluation System Medical Interaction Subscale [CARES-MIS]) were measured at baseline and monthly for 4 months. The primary outcome was change score for FACIT-Sp at 3 months. Secondary endpoints included change score for FACIT-Sp at 4 months and change scores for other scales at 3 and 4 months. This trial is registered with ClinicalTrials.gov, number NCT01248624. FINDINGS: 461 patients completed baseline measures (228 intervention, 233 control); 393 completed at least one follow-up assessment. At 3-months, there was a non-significant difference in change score for FACIT-Sp between intervention and control groups (3·56 points [95% CI -0·27 to 7·40], p=0·07), a significant difference in QUAL-E (2·25 [0·01 to 4·49], p=0·05) and FAMCARE-P16 (3·79 [1·74 to 5·85], p=0·0003), and no difference in ESAS (-1·70 [-5·26 to 1·87], p=0·33) or CARES-MIS (-0·66 [-2·25 to 0·94], p=0·40). At 4 months, there were significant differences in change scores for all outcomes except CARES-MIS. All differences favoured the intervention group. INTERPRETATION: Although the difference in quality of life was non-significant at the primary endpoint, this trial shows promising findings that support early palliative care for patients with advanced cancer. FUNDING: Canadian Cancer Society, Ontario Ministry of Health and Long Term Care.

Variability in research ethics review of cluster randomized trials: a scenario-based survey in three countries.

BACKGROUND: Cluster randomized trials (CRTs) present unique ethical challenges. In the absence of a uniform standard for their ethical design and conduct, problems such as variability in procedures and requirements by different research ethics committees will persist. We aimed to assess the need for ethics guidelines for CRTs among research ethics chairs internationally, investigate variability in procedures for research ethics review of CRTs within and among countries, and elicit research ethics chairs' perspectives on specific ethical issues in CRTs, including the identification of research subjects. The proper identification of research subjects is a necessary requirement in the research ethics review process, to help ensure, on the one hand, that subjects are protected from harm and exploitation, and on the other, that reviews of CRTs are completed efficiently. METHODS: A web-based survey with closed- and open-ended questions was administered to research ethics chairs in Canada, the United States, and the United Kingdom. The survey presented three scenarios of CRTs involving cluster-level, professional-level, and individual-level interventions. For each scenario, a series of questions was posed with respect to the type of review required (full, expedited, or no review) and the identification of research subjects at cluster and individual levels. RESULTS: A total of 189 (35%) of 542 chairs responded. Overall, 144 (84%, 95% CI 79 to 90%) agreed or strongly agreed that there is a need for ethics guidelines for CRTs and 158 (92%, 95% CI 88 to 96%) agreed or strongly agreed that research ethics committees could be better informed about distinct ethical issues surrounding CRTs. There was considerable variability among research ethics chairs with respect to the type of review required, as well as the identification of research subjects. The cluster-cluster and professional-cluster scenarios produced the most disagreement. CONCLUSIONS: Research ethics committees identified a clear need for ethics guidelines for CRTs and education about distinct ethical issues in CRTs. There is disagreement among committees, even within the same countries, with respect to key questions in the ethics review of CRTs. This disagreement reflects variability of opinion and practices pointing toward possible gaps in knowledge, and supports the need for explicit guidelines for the ethical conduct and review of CRTs.

Methotrexate in combination with infliximab is no more effective than infliximab alone in patients with Crohn's disease.

BACKGROUND & AIMS: Methotrexate and infliximab are effective therapies for Crohn's disease (CD). In the combination of maintenance methotrexate-infliximab trial, we evaluated the potential superiority of combination therapy over infliximab alone. METHODS: In a 50-week, double-blind, placebo-controlled trial, we compared methotrexate and infliximab with infliximab alone in 126 patients with CD who had initiated prednisone induction therapy (15-40 mg/day) within the preceding 6 weeks. Patients were assigned randomly to groups given methotrexate at an initial weekly dose of 10 mg, escalating to 25 mg/week (n = 63), or placebo (n = 63). Both groups received infliximab (5 mg/kg of body weight) at weeks 1, 3, 7, and 14, and every 8 weeks thereafter. Prednisone was tapered, beginning at week 1, and discontinued no later than week 14. The primary outcome was time to treatment failure, defined as a lack of prednisone-free remission (CD Activity Index, <150) at week 14 or failure to maintain remission through week 50. RESULTS: Patients' baseline characteristics were similar between groups. By week 50, the actuarial rate of treatment failure was 30.6% in the combination therapy group compared with 29.8% in the infliximab monotherapy group (P = .63; hazard ratio, 1.16; 95% confidence interval, 0.62-2.17). Prespecified subgroup analyses failed to show a benefit in patients with short disease duration or an increased level of C-reactive protein. No clinically meaningful differences were observed in secondary outcomes. Combination therapy was well tolerated. CONCLUSIONS: The combination of infliximab and methotrexate, although safe, was no more effective than infliximab alone in patients with CD receiving treatment with prednisone. ClincialTrials.gov number, NCT00132899.

Survey of consent practices in cluster randomized trials: improvements are needed in ethical conduct and reporting.

BACKGROUND: Informed consent procedures in cluster randomized trials (CRTs) are considerably more complicated than in individually randomized trials. In a CRT, the units of randomization, intervention, and observation may differ in a single trial; there can be multiple levels of participants (individual and cluster level); consent may be required separately for intervention and data collection; and there may be practical constraints to seeking informed consent, for example, due to cluster-level interventions or the sheer size of clusters. PURPOSE: We aimed to document consent practices at individual and cluster levels, assess the adequacy of reporting consent in trial publications, and assess associations with two trial characteristics that may influence consent requirements in CRTs: presence or absence of study interventions and presence or absence of data collection procedures at individual and cluster levels. METHODS: We reviewed a random sample of 300 CRTs published during 2000-2008. We sent survey questionnaires to 285 unique authors of these trials to gather detailed information about consent procedures used in each trial. RESULTS: In all, 182 authors (64%) responded. Overall, 93% (95% confidence interval (CI): 88.8%-96.6%) indicated that participant consent had been sought for some aspects of the study. Consent was less frequently sought for a study intervention (70% of respondents) than for data collection (88%). More than half of the respondents (52%) indicated that consent had been sought at both cluster and individual levels. There was strong evidence for under-reporting of consent in trial publications: only 63% of all trial publications reported that informed consent had been sought for some aspect of the study. The odds ratios (ORs) summarizing the association of the two trial characteristics with cluster-level participant consent were weak (OR = 1.17, p = 0.70 for presence of cluster-level study intervention and OR = 1.54, p = 0.29 for data collection); on the other hand, the ORs summarizing the associations with individual-level consent were strong (OR = 6.2, p < 0.0001 for presence of individual-level intervention and OR = 14.7, p < 0.0001 for data collection). LIMITATIONS: In all, 36% of authors did not respond to the survey; to the extent that consent practices in their trials were different than in respondents' trials, our results may be biased. CONCLUSIONS: There is a need for improvements in research practices in CRTs as well as their reporting. There may be a lack of clarity about consent requirements at the cluster level in particular. With the publication of the Ottawa Statement on the Ethical Design and Conduct of Cluster Randomized Trials, researchers and research ethics committees now have access to comprehensive ethics guidelines specific to CRTs.

5 year efficacy of a bivalent killed whole-cell oral cholera vaccine in Kolkata, India: a cluster-randomised, double-blind, placebo-controlled trial.

BACKGROUND: Efficacy and safety of a two-dose regimen of bivalent killed whole-cell oral cholera vaccine (Shantha Biotechnics, Hyderabad, India) to 3 years is established, but long-term efficacy is not. We aimed to assess protective efficacy up to 5 years in a slum area of Kolkata, India. METHODS: In our double-blind, cluster-randomised, placebo-controlled trial, we assessed incidence of cholera in non-pregnant individuals older than 1 year residing in 3933 dwellings (clusters) in Kolkata, India. We randomly allocated participants, by dwelling, to receive two oral doses of modified killed bivalent whole-cell cholera vaccine or heat-killed Escherichia coli K12 placebo, 14 days apart. Randomisation was done by use of a computer-generated sequence in blocks of four. The primary endpoint was prevention of episodes of culture-confirmed Vibrio cholerae O1 diarrhoea severe enough for patients to seek treatment in a health-care facility. We identified culture-confirmed cholera cases among participants seeking treatment for diarrhoea at a study clinic or government hospital between 14 days and 1825 days after receipt of the second dose. We assessed vaccine protection in a per-protocol population of participants who had completely ingested two doses of assigned study treatment. FINDINGS: 69 of 31 932 recipients of vaccine and 219 of 34 968 recipients of placebo developed cholera during 5 year follow-up (incidence 2·2 per 1000 in the vaccine group and 6·3 per 1000 in the placebo group). Cumulative protective efficacy of the vaccine at 5 years was 65% (95% CI 52-74; p<0·0001), and point estimates by year of follow-up suggested no evidence of decline in protective efficacy. INTERPRETATION: Sustained protection for 5 years at the level we reported has not been noted previously with other oral cholera vaccines. Established long-term efficacy of this vaccine could assist policy makers formulate rational vaccination strategies to reduce overall cholera burden in endemic settings. FUNDING: Bill & Melinda Gates Foundation and the governments of South Korea and Sweden.

Covariate-adjusted confidence interval for the intraclass correlation coefficient.

A crucial step in designing a new study is to estimate the required sample size. For a design involving cluster sampling, the appropriate sample size depends on the so-called design effect, which is a function of the average cluster size and the intracluster correlation coefficient (ICC). It is well-known that under the framework of hierarchical and generalized linear models, a reduction in residual error may be achieved by including risk factors as covariates. In this paper we show that the covariate design, indicating whether the covariates are measured at the cluster level or at the within-cluster subject level affects the estimation of the ICC, and hence the design effect. Therefore, the distinction between these two types of covariates should be made at the design stage. In this paper we use the nested-bootstrap method to assess the accuracy of the estimated ICC for continuous and binary response variables under different covariate structures. The codes of two SAS macros are made available by the authors for interested readers to facilitate the construction of confidence intervals for the ICC. Moreover, using Monte Carlo simulations we evaluate the relative efficiency of the estimators and evaluate the accuracy of the coverage probabilities of a 95% confidence interval on the population ICC. The methodology is illustrated using a published data set of blood pressure measurements taken on family members.

The role of centralized reading of endoscopy in a randomized controlled trial of mesalamine for ulcerative colitis.

BACKGROUND & AIMS: Interobserver differences in endoscopic assessments contribute to variations in rates of response to placebo in ulcerative colitis (UC) trials. We investigated whether centralized review of images could reduce these variations. METHODS: We performed a 10-week, randomized, double-blind, placebo-controlled study of 281 patients with mildly to moderately active UC, defined by an Ulcerative Colitis Disease Activity Index (UCDAI) sigmoidoscopy score ≥2, that evaluated the efficacy of delayed-release mesalamine (Asacol 800-mg tablet) 4.8 g/day. Endoscopic images were reviewed by a single expert central reader. The primary outcome was clinical remission (UCDAI, stool frequency and bleeding scores of 0, and no fecal urgency) at week 6. RESULTS: The primary outcome was achieved by 30.0% of patients treated with mesalamine and 20.6% of those given placebo, a difference of 9.4% (95% confidence interval [CI], -0.7% to 19.4%; P = .069). Significant differences in results from secondary analyses indicated the efficacy of mesalamine. Thirty-one percent of participants, all of whom had a UCDAI sigmoidoscopy score ≥2 as read by the site investigator, were considered ineligible by the central reader. After exclusion of these patients, the remission rates were 29.0% and 13.8% in the mesalamine and placebo groups, respectively (difference of 15%; 95% CI, 3.5%-26.0%; P = .011). CONCLUSIONS: Although mesalamine 4.8 g/day was not statistically different from placebo for induction of remission in patients with mildly to moderately active UC, based on an intent-to-treat analysis, the totality of the data supports a benefit of treatment. Central review of endoscopic images is critical to the conduct of induction studies in UC; ClinicalTrials.gov Number, NCT01059344.

Challenges in the research ethics review of cluster randomized trials: international survey of investigators.

BACKGROUND: Cluster randomized trials (CRTs) complicate the interpretation of standard research ethics guidelines for several reasons. For one, the units of allocation, intervention, and observation often may differ within a single trial. In the absence of tailored and internationally accepted ethics guidelines for CRTs, researchers and research ethics committees have no common standard by which to judge ethically appropriate practices in CRTs. Moreover, lack of familiarity with and consideration of the unique features of the CRT design by research ethics committees may cause difficulties in the research ethics review process, and amplify problems such as variability in the requirements and decisions reached by different research ethics committees. PURPOSE: We aimed to characterize research ethics review of CRTs, examine investigator experiences with the ethics review process, and assess the need for ethics guidelines for CRTs. METHODS: An electronic search strategy implemented in MEDLINE was used to identify and randomly sample 300 CRTs published in English language journals from 2000 to 2008. A web-based survey with closed- and open-ended questions was administered to corresponding authors in a series of six contacts. RESULTS: The survey response rate was 64%. Among 182 of 285 eligible respondents, 91% indicated that they had sought research ethics approval for the identified CRT, although only 70% respondents reported research ethics approval in the published article. Nearly one-third (31%) indicated that they have had to meet with ethics committees to explain aspects of their trials, nearly half (46%) experienced variability in the ethics review process in multijurisdictional trials, and 38% experienced negative impacts of the ethics review process on their trials, including delays in trial initiation (28%), increased costs (10%), compromised ability to recruit participants (16%), and compromised methodological quality (9%). Most respondents (74%; 95% confidence interval (CI): 67%-80%) agreed or strongly agreed that there is a need to develop ethics guidelines for CRTs, and (70%; 95% CI: 63%-77%) that ethics committees could be better informed about distinct ethical issues surrounding CRTs. LIMITATIONS: Thirty-six percent of authors did not respond to the survey. Due to the absence of comparable results from a representative sample of authors of individually randomized trials, it is unclear to what extent the reported challenges result from the CRT design. CONCLUSIONS: CRT investigators are experiencing challenges in the research ethics review of their trials, including excessive delays, variability in process and outcome, and imposed requirements that can have negative consequences for study conduct. Investigators identified a clear need for ethics guidelines for CRTs and education of research ethics committees about distinct ethical issues in CRTs.

A matched pair cluster randomized implementation trail to measure the effectiveness of an intervention package aiming to decrease perinatal mortality and increase institution-based obstetric care among indigenous women in Guatemala: study protocol.

BACKGROUND: Maternal and perinatal mortality continue to be a high priority problem on the health agendas of less developed countries. Despite the progress made in the last decade to quantify the magnitude of maternal mortality, few interventions have been implemented with the intent to measure impact directly on maternal or perinatal deaths. The success of interventions implemented in less developed countries to reduce mortality has been questioned, in terms of the tendency to maintain a clinical perspective with a focus on purely medical care separate from community-based approaches that take cultural and social aspects of maternal and perinatal deaths into account. Our innovative approach utilizes both the clinical and community perspectives; moreover, our study will report the weight that each of these components may have had on reducing perinatal mortality and increasing institution-based deliveries. METHODS/DESIGN: A matched pair cluster-randomized trial will be conducted in clinics in four rural indigenous districts with the highest maternal mortality ratios in Guatemala. The individual clinic will serve as the unit of randomization, with 15 matched pairs of control and intervention clinics composing the final sample. Three interventions will be implemented in indigenous, rural and poor populations: a simulation training program for emergency obstetric and perinatal care, increased participation of the professional midwife in strengthening the link between traditional birth attendants (TBA) and the formal health care system, and a social marketing campaign to promote institution-based deliveries. No external intervention is planned for control clinics, although enhanced monitoring, surveillance and data collection will occur throughout the study in all clinics throughout the four districts. All obstetric events occurring in any of the participating health facilities and districts during the 18 months implementation period will be included in the analysis, controlling for the cluster design. Our main outcome measures will be the change in perinatal mortality and in the proportion of institution-based deliveries. DISCUSSION: A unique feature of this protocol is that we are not proposing an individual intervention, but rather a package of interventions, which is designed to address the complexities and realities of maternal and perinatal mortality in developing countries. To date, many other countries, has focused its efforts to decrease maternal mortality indirectly by improving infrastructure and data collection systems rather than on implementing specific interventions to directly improve outcomes. TRIAL REGISTRATION: ClinicalTrial.gov,http://NCT01653626.

Herd protection by a bivalent killed whole-cell oral cholera vaccine in the slums of Kolkata, India.

BACKGROUND: We evaluated the herd protection conferred by an oral cholera vaccine using 2 approaches: cluster design and geographic information system (GIS) design. METHODS: Residents living in 3933 dwellings (clusters) in Kolkata, India, were cluster-randomized to receive either cholera vaccine or oral placebo. Nonpregnant residents aged≥1 year were invited to participate in the trial. Only the first episode of cholera detected for a subject between 14 and 1095 days after a second dose was considered. In the cluster design, indirect protection was assessed by comparing the incidence of cholera among nonparticipants in vaccine clusters vs those in placebo clusters. In the GIS analysis, herd protection was assessed by evaluating association between vaccine coverage among the population residing within 250 m of the household and the occurrence of cholera in that population. RESULTS: Among 107 347 eligible residents, 66 990 received 2 doses of either cholera vaccine or placebo. In the cluster design, the 3-year data showed significant total protection (66% protection, 95% confidence interval [CI], 50%-78%, P<.01) but no evidence of indirect protection. With the GIS approach, the risk of cholera among placebo recipients was inversely related to neighborhood-level vaccine coverage, and the trend was highly significant (P<.01). This relationship held in multivariable models that also controlled for potentially confounding demographic variables (hazard ratio, 0.94 [95% CI, .90-.98]; P<.01). CONCLUSIONS: Indirect protection was evident in analyses using the GIS approach but not the cluster design approach, likely owing to considerable transmission of cholera between clusters, which would vitiate herd protection in the cluster analyses. CLINICAL TRIALS REGISTRATION: NCT00289224.