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PubMed2003

Is there evidence of implicit exclusion criteria for elderly subjects in randomized trials? Evidence from the GUSTO-1 study.

BACKGROUND: Some experts have raised concerns about the ability to generalize randomized trials, emphasizing that patients who participate in these studies are often not representative of those seen in clinical practice, particularly in the case of elderly patients. To determine the effect of implicit exclusion criteria on a trial study sample, we compared data from the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO) trial with data from a retrospective registry from selected hospitals, the National Registry of Myocardial Infarction (NRMI), and a nationally representative study of myocardial infarction care, the Cooperative Cardiovascular Project (CCP). METHODS: We compared GUSTO subjects aged 65 years and older who were enrolled in the United States with similarily aged patients in the 2 observational studies who met the trial's eligibility criteria. We examined baseline characteristics, clinical presentation, treatments, procedures, clinical events, and in-hospital mortality rates. RESULTS: We found modest, although significant, differences between patients in NRMI, CCP, and GUSTO in demographic and clinical characteristics, treatment, and outcome. For example, GUSTO patients were significantly younger (73.1 +/- 5.7 vs 74.7 +/- 6.8 for NRMI and 75.8 +/- 7.2 for CCP), less likely to have Killip class III/IV at presentation (3.1% vs 6.2% for NRMI and 32.7% for CCP), and more likely to receive aspirin (95.5% vs 86.3% for NRMI and 86.5% for CCP) and beta-blockers (71.9% vs 43.5% for NRMI and 52.7% for CCP). Overall, NRMI and CCP patients had a lower risk of 30-day mortality after adjustment for demographic, clinical, and hospital characteristics than patients in GUSTO (odds ratio, 0.79; 95% CI, 0.73-0.86 for NRMI; odds ratio, 0.65; 95% CI, 0.59-0.71 for CCP). CONCLUSIONS: Older patients enrolled in a randomized trial without an age restriction had many similarities compared with patients seen in clinical practice. The higher mortality rate of the GUSTO patients does not support the hypothesis that the trial enrolled a healthier cohort than is seen in practice.

Age Distribution↗

PubMed2005

Menopausal hormone therapy after breast cancer: the Stockholm randomized trial.

In 1997 two independent randomized clinical trials, Hormonal Replacement Therapy After Breast Cancer--Is It Safe? (HABITS; 434 patients) and the Stockholm trial (378 patients), were initiated in Sweden to compare menopausal hormone therapy with no menopausal hormone therapy after diagnosis of early-stage breast cancer. Much of the design of both studies was similar; however, a goal of the Stockholm protocol, not shared with the HABITS trial, was to minimize the use of progestogen combined with estrogen. The HABITS trial was prematurely stopped in December 2003, because, at a median follow-up of 2.1 years, the risk for recurrence of breast cancer among patients receiving menopausal hormone therapy was statistically significantly higher (relative hazard [RH] = 3.3, 95% confidence interval [CI] = 1.5 to 7.4) than among those receiving no treatment. In the Stockholm trial, however, at a median follow-up of 4.1 years, the risk of breast cancer recurrence was not associated with menopausal hormone therapy (RH = 0.82, 95% CI = 0.35 to 1.9). Statistically significant heterogeneity in the rate of recurrence was observed (P = .02; two-sided likelihood-ratio test) between the two studies, indicating that chance may not be the only explanation. Doses of estrogen and progestogen and treatment regimens for menopausal hormone therapy may be associated with the recurrence of breast cancer.

Aged↗

PubMed2005

Prior distributions for the intracluster correlation coefficient, based on multiple previous estimates, and their application in cluster randomized trials.

Numerous estimates for the intracluster correlation coefficient (ICC) are available in research databases and publications. When planning a cluster randomized trial, an anticipated value for the ICC is required; currently, researchers base their choice informally on the magnitude of previous ICC estimates. In this paper, we make use of the wealth of ICC information by formally constructing informative prior distributions, while acknowledging the varying relevance and precision of the estimates available. Typically, for a planned trial in a given clinical setting, multiple relevant ICC estimates are available from each of several completed studies. Our preferred model allows for the imprecision in each ICC estimate around its underlying true value and, separately, allows for the similarity of ICC values from the same study. The relevance of each previous estimate to the planned clinical setting is considered, and estimates corresponding to less relevant outcomes or population types are given less influence. We find that such downweighting can increase the precision of the anticipated ICC. In trial design, the prior distribution constructed allows uncertainty about the ICC to be acknowledged, and we describe how to choose a design that provides adequate power across the range of likely ICC values. Prior information on the ICC can also be incorporated in analysis of the trial data, when taking a Bayesian approach. The methods proposed enable available ICC information to be summarised appropriately by an informative prior distribution, which is of direct practical use in cluster randomized trials.

Bayes Theorem↗

PubMed1994

Randomized trials of primary prevention of cardiovascular disease in women. An investigator's view.

In recent years, increasing attention has focused on the need for more research to be conducted in women on health issues directly relevant to women. No one would disagree that the need for such studies is both crucial and timely. However, while the need for more research in women is urgent, the planning and conduct of such studies must always be driven by good science. Specifically, investigations in women may have unique and important scientific and logistic problems which must be recognized and addressed. However, if the trials are well designed and conducted, they will provide a sound and reliable body of data upon which to base rational clinical decision making and public health recommendations for women from women. These general issues are discussed in the context of a particular trial, the Women's Health Study, a randomized trial of the risks and benefits of low-dose aspirin, beta-carotene and vitamin E in the primary prevention of cardiovascular disease and cancer among healthy women.

Aspirin↗

PubMed1994

[Radiation therapy for brain metastases from lung carcinoma: the second prospective randomized trial].

Since September 1980 we have been conducting a prospective randomized trial to determine the best treatment schedule for radiation therapy (XRT) of brain metastasis from lung carcinoma. The first trial (September 1980 to December 1984) used random allocation of two different time-dose radiotherapy schemes: 30 Gy/10 fractions/2 weeks versus 50 Gy/20 fr./4 wks. Treatment results showed no significant difference in neurological improvement or survival between the two arms or in lactate dehydrogenase (LDH) as the most important prognostic factor. The current study (January 1985 to April 1992) examined two sequential trials stratified according to the level of LDH and included 162 patients with brain metastasis from lung carcinoma. Whole brain doses were 30 Gy/10 fr./2 wks (group A, n = 46) or 50 Gy/20 fr./4 wks. (group B, n = 46) in the normal LDH group and 30 Gy/10 fr./2 wks (group C, n = 35) or 20 Gy/5 fr./1 wk. (group D, n = 35) in the high LDH group, while the treatment field was lessened to 30 Gy in group B if possible. The final results showed that 1) the most important prognostic factor as determined by Cox's multivariate analysis was also LDH in the second trial; 2) the incidence of acute side effects tended to depend upon a single dose, i.e., group A (3 Gy) 35% versus group B (2.5 Gy) 21% (p = 0.165), and group C (3 Gy) 23% versus group D (4 Gy) 46% (p = 0.044); 3) median survival time and 1-year survival rates were 5.4 months and 21% in group A, 4.8 months and 17% in group B; 3.4 months and 6% in group C; and 2.4 months and 4% in group D, respectively, and survival curves showed no statistically significant difference between the two treatment groups in each LDH group; 4) improvement in neurological function appeared to increase with total dosage escalation, i.e., 41% in group A versus 45% in group B, and 35% in group C versus 21% in group D (not significant). In conclusion, a short intensive course (30 Gy/10 fr./2 wks) is advantageous for XRT because of the short treatment time and minor acute toxicity in spite of stratification by the level of LDH.

Aged↗

PubMed2004

Allowing for imprecision of the intracluster correlation coefficient in the design of cluster randomized trials.

The sample size required for a cluster randomized trial depends on the magnitude of the intracluster correlation coefficient (ICC). The usual sample size calculation makes no allowance for the fact that the ICC is not known precisely in advance. We develop methods which allow for the uncertainty in a previously observed ICC, using a variety of distributional assumptions. Distributions for the power are derived, reflecting this uncertainty. Further, the observed ICC in a future study will not equal its true value, and we consider the impact of this on power. We implement calculations within a Bayesian simulation approach, and provide one simplification that can be performed using simple simulation within spreadsheet software. In our examples, recognizing the uncertainty in a previous ICC estimate decreases expected power, especially when the power calculated naively from the ICC estimate is high. To protect against the possibility of low power, sample sizes may need to be very substantially increased. Recognizing the variability in the future observed ICC has little effect if prior uncertainty has already been taken into account. We show how our method can be extended to the case in which multiple prior ICC estimates are available. The methods presented in this paper can be used by applied researchers to protect against loss of power, or to choose a design which reduces the impact of uncertainty in the ICC.

Bayes Theorem↗

PubMed1981

Treatment of graft-versus-host disease in human allogeneic marrow graft recipients: a randomized trial comparing antithymocyte globulin and corticosteroids.

This prospective randomized trial compared the effect of antihuman thymocyte globulin (ATG) versus corticosteroids as treatment of graft-versus-host disease (GVHD) in recipients of HLA-identical allogeneic bone marrow transplants. Patients undergoing transplantation as therapy for either hematologic malignancies or aplastic anemia were given methotrexate as postgrafting immunosuppression. Patients who nevertheless developed acute GVHD of moderate severity were randomized to receive either corticosteroid therapy or ATG therapy. Thirty-seven patients were randomized: 20 patients received corticosteroids, and 17 received ATG. Both ATG and corticosteroids were in general well tolerated, although all patients receiving ATG developed fever and chills. Both treatment modalities were associated with a mild decrease in severity of GVHD after therapy. There was, however, no significant difference between treatment groups, whether assessed by improvement in specific organ involvement, improvement in the overall grade of GVHD, need for additional therapy for acute GVHD, or the proportion of patients who developed chronic GVHD. Infectious complications and survival were also not different between treatment groups. Thus, corticosteroids were as effective as ATG for the treatment of acute GVHD in recipients of HLA-identical marrow transplants and, therefore, appear to be a reasonable choice as primary therapy for acute GVHD.

Adult↗

PubMed1995

An analytic method for randomized trials with informative censoring: Part II.

Consider a randomized trial in which time to the occurrence of a particular disease, say pneumocystic pneumonia in an AIDS trial or breast cancer in a mammographic screening trial, is the failure time of primary interest. Suppose that time to disease is subject to informative censoring by the minimum of time to death, loss to and end of follow-up. In such a trial, the potential censoring time is observed for all study subjects, including failure. In the presence of informative censoring, it is not possible to consistently estimate the effect of treatment on time to disease without imposing additional non-identifiable assumptions. Robins (1995) specified two non-identifiable assumptions that allow one to test for and estimate an effect of treatment on time to disease in the presence of informative censoring. The goal of this paper is to provide a class of consistent and reasonably efficient semiparametric tests and estimators for the treatment effect under these assumptions. The tests in our class, like standard weighted-log-rank tests, are asymptotically distribution-free alpha-level tests under the null hypothesis of no causal effect of treatment on time to disease whenever the censoring and failure distributions are conditionally independent given treatment arm. However, our tests remain asymptotically distribution-free alpha-level tests in the presence of informative censoring provided either of our assumptions are true. In contrast, a weighted log-rank test will be an alpha-level test in the presence of informative censoring only if (1) one of our two non-identifiable assumptions hold, and (2) the distribution of time to censoring is the same in the two treatment arms. We also study the estimation, in the presence of informative censoring, of the effect of treatment on the evolution over time of the mean of repeated measures outcome such as CD4 count.

Causality↗

PubMed1995

An analytic method for randomized trials with informative censoring: Part 1.

Consider a randomized trial in which time to the occurrence of a particular disease, say pneumocystis pneumonia in an AIDS trial or breast cancer in a mammographic screening trial, is the failure time of primary interest. Suppose that time to disease is subject to informative censoring by the minimum of time to death, loss to and end of follow-up. In such a trial, the censoring time is observed for all study subjects, including failures. In the presence of informative censoring, it is not possible to consistently estimate the effect of treatment on time to disease without imposing additional non-identifiable assumptions. The goals of this paper are to specify two non-identifiable assumptions that allow one to test for and estimate an effect of treatment on time to disease in the presence of informative censoring. In a companion paper (Robins, 1995), we provide consistent and reasonably efficient semiparametric estimators for the treatment effect under these assumptions. In this paper we largely restrict attention to testing. We propose tests that, like standard weighted-log-rank tests, are asymptotically distribution-free alpha-level tests under the null hypothesis of no causal effect of treatment on time to disease whenever the censoring and failure distributions are conditionally independent given treatment arm. However, our tests remain asymptotically distribution-free alpha-level tests in the presence of informative censoring provided either of our assumptions are true. In contrast, a weighted log-rank test will be an alpha-level test in the presence of informative censoring only if (1) one of our two non-identifiable assumptions hold, and (2) the distribution of time to censoring is the same in the two treatment arms. We also extend our methods to studies of the effect of a treatment on the evolution over time of the mean of a repeated measures outcome, such as CD-4 count.

Causality↗

PubMed2001

Mitoxantrone is superior to doxorubicin in a multiagent weekly regimen for patients older than 60 with high-grade lymphoma: results of a BNLI randomized trial of PAdriaCEBO versus PMitCEBO.

A prospective, multicenter, randomized trial was undertaken to compare the efficacy and toxicity of adriamycin with mitoxantrone within a 6-drug combination chemotherapy regimen for elderly patients (older than 60 years) with high-grade non-Hodgkin lymphoma (HGL) given for a minimum of 8 weeks. A total of 516 previously untreated patients aged older than 60 years were randomized to receive 1 of 2 anthracycline-containing regimens: adriamycin, 35 mg/m(2) intravenously (IV) on day 1 (n = 259), or mitoxantrone, 7 mg/m(2) IV on day 1 (n = 257); with prednisolone, 50 mg orally on days 1 to 14; cyclophosphamide, 300 mg/m(2) IV on day 1; etoposide, 150 mg/m(2) IV on day 1; vincristine, 1.4 mg/m(2) IV on day 8; and bleomycin, 10 mg/m(2) IV on day 8. Each 2-week cycle was administered for a minimum of 8 weeks in the absence of progression. Forty-three patients were ineligible for analysis. The overall and complete remission rates were 78% and 60% for patients receiving PMitCEBO and 69% and 52% for patients receiving PAdriaCEBO (P =.05, P =.12, respectively). Overall survival was significantly better with PMitCEBO than PAdriaCEBO (P =.0067). However, relapse-free survival was not significantly different (P =.16). At 4 years, 28% of PAdriaCEBO patients and 50% of PMitCEBO patients were alive (P =.0001). Ann Arbor stage III/IV, World Health Organization performance status 2-4, and elevated lactate dehydrogenase negatively influenced overall survival from diagnosis. In conclusion, the PMitCEBO 8-week combination chemotherapy regimen offers high response rates, durable remissions, and acceptable toxicity in elderly patients with HGL.

Aged↗

PubMed2001

The design features and practicalities of conducting a pragmatic cluster randomized trial of obesity management in primary care.

The aim of this paper is to describe the design features and practicalities of conducting a cluster randomized trial of obesity management in primary care. The aim of the trial is to assess the effectiveness of an obesity management educational intervention delivered to staff within primary care practices (unit of randomization) in terms of change in body weight of their patients (unit of analysis) at one year. The design features which merit particular attention in this cluster randomized trial include standardization of intervention, sample size considerations, recruitment of patients prior to randomization of practices, method of randomization to balance control and intervention practices with respect to practice and patient level characteristics, and blinding of outcome assessment. The practical problems (and our solutions) associated with implementing these design features, particularly those that result in a time delay between baseline data collection, randomization and intervention, are discussed.

Adolescent↗

PubMed2002

A comparison of confidence interval methods for the intraclass correlation coefficient in cluster randomized trials.

This study compared different methods for assigning confidence intervals to the analysis of variance estimator of the intraclass correlation coefficient (rho). The context of the comparison was the use of rho to estimate the variance inflation factor when planning cluster randomized trials. The methods were compared using Monte Carlo simulations of unbalanced clustered data and data from a cluster randomized trial of an intervention to improve the management of asthma in a general practice setting. The coverage and precision of the intervals were compared for data with different numbers of clusters, mean numbers of subjects per cluster and underlying values of rho. The performance of the methods was also compared for data with Normal and non-Normally distributed cluster specific effects. Results of the simulations showed that methods based upon the variance ratio statistic provided greater coverage levels than those based upon large sample approximations to the standard error of rho. Searle's method provided close to nominal coverage for data with Normally distributed random effects. Adjusted versions of Searle's method to allow for lack of balance in the data generally did not improve upon it either in terms of coverage or precision. Analyses of the trial data, however, showed that limits provided by Thomas and Hultquist's method may differ from those of the other variance ratio statistic methods when the arithmetic mean differs markedly from the harmonic mean cluster size. The simulation results demonstrated that marked non-Normality in the cluster level random effects compromised the performance of all methods. Confidence intervals for the methods were generally wide relative to the underlying size of rho suggesting that there may be great uncertainty associated with sample size calculations for cluster trials where large clusters are randomized. Data from cluster based studies with sample sizes much larger than those typical of cluster randomized trials are required to estimate rho with a reasonable degree of precision.

Adolescent↗

PubMed2001

Postpartum positioning and attachment education for increasing breastfeeding: a randomized trial.

BACKGROUND: Although lactation experts suggest that a correct positioning and attachment technique reduces breastfeeding problems and enhances long-term breastfeeding, evidence from randomized trials is lacking. The objective of this study was to evaluate the effect of postpartum positioning and attachment education on breastfeeding outcomes in first-time mothers. METHOD: A randomized trial was performed in a public hospital in Adelaide, South Australia, where 160 first-time mothers were randomly allocated to receive either structured one-to-one education (experimental group) or usual postpartum care (control group) within 24 hours of birth. The primary outcome was breastfeeding at 6 weeks and 3 and 6 months postpartum; other outcomes were nipple pain and trauma in hospital and at 6 weeks and 3 and 6 months, and satisfaction with breastfeeding. RESULTS: No significant differences occurred in breastfeeding rates between the groups at each endpoint, although a trend in the direction of lower rates was seen at each endpoint in the experimental group. This group reported less nipple pain on days 2 (p = 0.004) and 3 (p = 0.04), but this was not sustained on follow-up. No differences were observed in nipple trauma in hospital or in self-reported nipple pain and/or trauma at the three endpoints. Experimental group women were less satisfied with breastfeeding at 3 and 6 months postpartum when using a one-item measure; however, a multiple-item measure showed no significant differences at the three endpoints. CONCLUSIONS: The intervention did not increase breastfeeding duration at any assessment time or demonstrate any differences between the groups on secondary outcomes. The trend toward lower breastfeeding rates in the experimental group suggests a need for a larger trial to evaluate whether or nor postpartum positioning and attachment education may negatively affect breastfeeding.

Adult↗

PubMed2003

Early autologous stem-cell transplantation versus conventional chemotherapy as front-line therapy in high-risk, aggressive non-Hodgkin's lymphoma: an Italian multicenter randomized trial.

PURPOSE: To evaluate the role of early intensification with high-dose therapy (HDT) and autologous stem-cell transplantation (ASCT) as front-line chemotherapy for patients with high-risk, histologically aggressive non-Hodgkin's lymphoma (NHL). PATIENTS AND METHODS: We planned a multicenter, randomized trial to compare a conventional chemotherapy regimen of methotrexate with leucovorin rescue, doxorubicin, cyclophosphamide, vincristine, prednisone, and bleomycin (MACOP-B; arm A) with an abbreviated regimen of MACOP-B (8 weeks) followed by HDT and ASCT (arm B) for intermediate-high-risk/high-risk patients (according to the age-adjusted International Prognostic Index). From September 1994 to April 1998, 150 patients with aggressive lymphoma were enrolled onto the trial. Seventy-five patients were randomly assigned to arm A and 75 patients were randomly assigned to arm B. In both arms, involved-field radiation therapy (36 Gy) was delivered to the site of bulky disease. RESULTS: The rate of complete response was 68% in arm A and 76% in arm B (P = not significant [NS]). Three toxic deaths (4%) occurred in arm B and one (1%) occurred in arm A (P = NS). In arm B, 30 patients (40%) did not undergo HDT and ASCT. According to the intention-to-treat analysis at a median follow-up of 24 months, 5-year overall survival probability in arms A and B was 65% and 64% (P =.95), 5-year progression-free survival was 49% and 61% (P =.21), and 5-year relapse-free survival was 65% and 77% (P =.22), respectively. CONCLUSION: Abbreviated chemotherapy followed by intensification with HDT-ASCT is not superior to conventional chemotherapy in patients with high-risk, aggressive NHL. Additional randomized trials will clarify whether HDT-ASCT as front-line therapy after a complete course of conventional chemotherapy improves survival in this group of patients.

Adolescent↗

PubMed1998

Can midwives reduce postpartum psychological morbidity? A randomized trial.

BACKGROUND: Women who are traumatized after childbirth find that listening, support, counseling, understanding, and explanation are the most useful treatments. However, little evidence is available from randomized trials of the relative efficacy of these treatments as a positive postnatal intervention. This study purpose was to examine if postnatal "debriefing" by midwives can reduce psychological morbidity after childbirth. METHOD: A randomized trial was conducted in a regional teaching hospital in northwest England. One hundred and twenty postnatal primigravidas were allocated by sealed envelopes to receive the debriefing intervention (n = 56) or not (n = 58). The main outcome measure was the Hospital Anxiety and Depression (HAD) scale administered by postal questionnaire 3 weeks after delivery. The proportion of women in each group with anxiety and depression scores of more than 10 points were compared, using odds ratios and 95% confidence intervals. RESULTS: Women who received the intervention were less likely to have high anxiety and depression scores after delivery when compared with the control group. CONCLUSIONS: The support, counseling, understanding, and explanation given to women by midwives in the postnatal period provides benefits to psychological well-being. Maternity units have a responsibility to develop a service that offers all women the option of attending a session to discuss their labor.

Adult↗

PubMed1999

Acupuncture as a treatment for temporomandibular joint dysfunction: a systematic review of randomized trials.

OBJECTIVE: To summarize the data from randomized controlled trials of acupuncture for temporomandibular joint dysfunction. METHODS: Four independent computerized literature searches were performed. Only randomized trials were admitted in which acupuncture was tested vs sham acupuncture, standard therapy, or no treatment at all. Data were extracted in a predefined, standardized fashion. RESULTS: Six reports met the inclusion and exclusion criteria, representing 3 distinct trials. Overall, their results suggest that acupuncture might be an effective therapy for temporomandibular joint dysfunction. However, none of the studies was designed to control for a placebo effect. CONCLUSION: Even though all studies are in accordance with the notion that acupuncture is effective for temporomandibular joint dysfunction, this hypothesis requires confirmation through more rigorous investigations.

Acupuncture Therapy↗

PubMed2006

Three-year follow-up of a prospective randomized trial comparing laparoscopic versus open gastric bypass.

OBJECTIVE: To analyze long-term weight loss, changes in comorbidities and quality of life, and late complications after laparoscopic and open gastric bypass. SUMMARY BACKGROUND DATA: Early results from our prospective randomized trial comparing the outcome of laparoscopic versus open gastric bypass demonstrated less postoperative pain, shorter length of hospital stay, fewer wound-related complications, and faster convalescence for patients who underwent laparoscopic gastric bypass. METHODS: Between May 1999 and March 2001, 155 morbidly obese patients were enrolled in this prospective trial, in which 79 patients were randomized to laparoscopic gastric bypass and 76 to open gastric bypass. Two patients in the laparoscopic group required conversion to open surgery; their data were analyzed within the laparoscopic group on an intention-to-treat basis. The 2 groups were well matched for body mass index, age, and gender. Outcome evaluation included weight loss, changes in comorbidities and quality of life, and late complications. RESULTS: The mean follow-up was 39+/-8 months. There were no significant differences in the percent of excess body weight loss between the 2 groups at the 3-year follow-up (77% for laparoscopic versus 67% for open). The rate of improvement or resolution of comorbidities was similar between groups. Improvement in quality of life, measured by the Moorehead-Ardelt Quality of Life Questionnaire, was observed in both groups without significant differences between groups. Late complications were similar between groups except for the rate of incisional hernia, which was significantly greater after open gastric bypass (39% versus 5%, P<0.01), and the rate of cholecystectomy, which was greater after laparoscopic gastric bypass (28% versus 5%, P=0.03). CONCLUSIONS: In this randomized trial with a 3-year follow-up, we found that laparoscopic gastric bypass was equally effective as open gastric bypass with respect to weight loss and improvement in comorbidities and quality of life. A major advantage at long-term follow-up for patients who underwent laparoscopic gastric bypass was the reduction in the rate of incisional hernia.

Adult↗

PubMed1989

Randomized trials of perinatal interventions in Belgium and Europe.

Using statistics from United Nations Demographic Yearbooks (1958-1983) and the Oxford Database of Perinatal Trials, a survey of perinatal randomized control trials (RCTs) during the last 25 years in Europe was performed. Total number of trials has been related to average annual population, average annual total births and average annual total of medical doctors. There is a clear geographical trend; Finland, Denmark, Sweden, Ireland and the United Kingdom in the leading group produce, on average, 50 times as many randomized trials as socialist countries other than Hungary and the German Democratic Republic. Within Belgium itself, similar disparities are observed: university A has produced twice as many RCTs as all the other universities pooled together. For Belgium, the introduction of multicenter trials may be reversing this situation, and uptake of ongoing multicenter trials seems homogeneous within the country.

Belgium↗