Some design issues in trials of microbicides for the prevention of HIV infection

Trials for the prevention of human immunodeficiency virus (HIV) infection that evaluate microbicides provide significant design challenges. Three of these design issues deserve more careful consideration. The first issue relates to the benefits of using both blinded and unblinded control groups when the placebo regimen may not be inert and when the effectiveness of an intervention heavily depends on behavioral, as well as biological, factors. The second issue relates to the strength of evidence required for regulatory approval for the marketing of drugs and biologics when only a single pivotal phase 3 clinical trial has provided such evidence. The third issue relates to the appropriate next step after the completion of phase 1 trials, as well as the specific merits of conducting phase 2b screening trials that assess the effects on the same clinical efficacy end point that will be the primary end point in a phase 3 trial. The issues considered in microbicide trials for the prevention of HIV infection are also of importance in many other clinical scenarios.

Quality assurance of the EORTC 26981/22981; NCIC CE3 intergroup trial on radiotherapy with or without temozolomide for newly-diagnosed glioblastoma multiforme: the individual case review

The phase III randomised European Organisation for Research and Treatment of Cancer (EORTC) and National Cancer Institute of Canada Clinical Trail Group (NCIC) Intergroup trial (EORTC 26981/22981; CE3) compares irradiation alone with irradiation plus temozolomide for patients with glioblastoma multiforme (GBM). We evaluated the compliance to radiotherapy (RT) guidelines. All 85 recruiting centres were invited to participate in the individual case review. Fifty-four centres (64%) entering 71% of the patients provided data on one randomly selected patient. All participating centres used individual head immobilisation and computerised tomography (CT)-based treatment planning. Most (74%) performed three-dimensional conformal radiotherapy (3-D-CRT) including dose-volume histograms. Ninety-four percent performed portal imaging at least once. Planning target volume (PTV) and structures at risk were delineated in most of the centres (94%). Although the PTV received < 95% of the prescription dose (60 Gy in 2 Gy/fraction/day) in 39% of the centres; all except 2 centres delivered 50-60 Gy to the PTV. The maximum dose to the critical structures exceeded the protocol dose constraints in 39% of the reviewed patients, but in only 9% was this over the acceptable tolerance dose reported in the literature. We found a high rate of compliance with the protocol and general RT guidelines in the centres participating in this individual case review. In multicentre trials with a large of number of investigators from international and national groups, it is essential to confirm the interinstitutional consistency, qualitatively and quantitatively.

Satisfaction of the uncertainty principle in cancer clinical trials: retrospective cohort analysis

OBJECTIVE

To assess whether publicly funded adult cancer trials satisfy the uncertainty principle, which states that physicians should enroll a patient in a trial only if they are substantially uncertain which of the treatments in the trial is most appropriate for the patient. This principle is violated if trials systematically favour either the experimental or the standard treatment.

DESIGN

Retrospective cohort study of completed cancer trials, with randomisation as the unit of analysis.

SETTING

Two cooperative research groups in the United States.

STUDIES INCLUDED

93 phase III randomised trials (103 randomisations) that completed recruitment of patients between 1981 and 1995.

MAIN OUTCOME MEASURES

Whether the randomisation favoured the experimental treatment, the standard treatment, or neither treatment; effect size (outcome of the experimental treatment compared with outcome of the standard treatment) for each randomisation.

RESULTS

Three randomisations (3%) favoured the standard treatment, 70 (68%) found no significant difference between treatments, and 30 (29%) favoured the experimental treatment. The average effect size was 1.20 (95% confidence interval 1.13 to 1.28), reflecting a slight advantage for the experimental treatment.

CONCLUSIONS

In cooperative group trials in adults with cancer, there is a measurable average improvement in disease control associated with assignment to the experimental rather than the standard arm. However, the heterogeneity of outcomes and the small magnitude of the advantage suggest that, as a group, these trials satisfy the uncertainty principle.

What is the appropriate role of the trial statistician in preparing and presenting interim findings to an independent Data Monitoring Committee in the U.S. Cancer Cooperative Group setting?

A recent draft FDA Guidance on the establishment and operation of clinical trial Data Monitoring Committees (DMCs) suggests that statisticians who prepare and present interim analyses to the DMC should be external to the trial sponsor. In the context of the National Cancer Institute (NCI) Cooperative Group program, this recommendation appears to imply that Group study statisticians should be blinded to interim data and excluded from the interim monitoring process in all Cooperative Group trials. In this commentary, it is argued that the benefits of such a policy would be minimal in the Cooperative Group setting and are far outweighed by the tangible benefits of including the study statistician in the monitoring process.

Bad reporting does not mean bad methods for randomised trials: observational study of randomised controlled trials performed by the Radiation Therapy Oncology Group

OBJECTIVE

To determine whether poor reporting of methods in randomised controlled trials reflects on poor methods.

DESIGN

Observational study.

SETTING

Reports of randomised controlled trials conducted by the Radiation Therapy Oncology Group since its establishment in 1968.

PARTICIPANTS

The Radiation Therapy Oncology Group. Outcome measures Content of reports compared with the design features described in the protocols for all randomised controlled trials.

RESULTS

The methodological quality of 56 randomised controlled trials was better than reported. Adequate allocation concealment was achieved in all trials but reported in only 42% of papers. An intention to treat analysis was done in 83% of trials but reported in only 69% of papers. The sample size calculation was performed in 76% of the studies, but reported in only 16% of papers. End points were clearly defined and alpha and beta errors were prespecified in 76% and 74% of the trials, respectively, but only reported in 10% of the papers. The one exception was the description of drop outs, where the frequency of reporting was similar to that contained in the original statistical files of the Radiation Therapy Oncology Group.

CONCLUSIONS

The reporting of methodological aspects of randomised controlled trials does not necessarily reflect the conduct of the trial. Reviewing research protocols and contacting trialists for more information may improve quality assessment.

Assessment of Differences in Patient Populations Selected for or Excluded From Participation in Clinical Phase III Acute Myelogenous Leukemia Trials

Purpose: To compare patients treated in or outside clinical protocols, using de novo acute myeloid leukemia (AML) as a model disorder.

Patients and Methods: We retrospectively compared the characteristics of all patients with de novo AML diagnosed in the referral area of our university hospital between 1985 and 1994.

Results: Of a total of 170 AML patients, 45% were included in a phase III trial for the treatment of AML and 55% were treated outside a protocol. Another 45 patients were registered only at diagnosis but were treated elsewhere. Nonstudy patients differed significantly from patients included in clinical trials with respect to age and performance status at clinical presentation, comorbidity, and type of AML. The great majority of patients excluded from trial participation showed distinct exclusion criteria, such as advanced age and severe comorbidity. Study patients were treated significantly more often with curative intent and achieved better response and survival. Patients treated in an equivalent manner but outside a protocol showed no significant difference in survival compared with patients enrolled onto a trial.

Conclusion: Study patients were not representative for the entire population of patients with AML; many patients were excluded from phase III trial participation for failure to meet stringent entry criteria. Therefore, results of phase III studies may not be extrapolated to all AML patients but should only be applied to patients who do not differ in substantial characteristics from the study population.

Outcome variables for osteoarthritis clinical trials: The OMERACT-OARSI set of responder criteria

Improvement in analysis and reporting results of osteoarthritis (OA) clinical trials has been recently obtained because of harmonization and standardization of the selection of outcome variables (OMERACT 3 and OARSI). Moreover, OARSI has recently proposed the OARSI responder criteria. This composite index permits presentation of results of symptom modifying clinical trials in OA based on individual patient responses (responder yes/no). The 2 organizations (OMERACT and OARSI) established a task force aimed at evaluating: (1) the variability of observed placebo and active treatment effects using the OARSI responder criteria; and (2) the possibility of proposing a simplified set of criteria. The conclusions of the task force were presented and discussed during the OMERACT 6 conference, where a simplified set of responder criteria (OMERACT-OARSI set of criteria) was proposed.

Trials and tribulations: current challenges in conducting clinical trials

Randomized controlled trials are the gold standard for the evaluation of new therapies and surgical procedures and as such require strict attention to study design and statistical analysis. There are, however, multiple challenges in conducting a well-designed clinical trial. This article describes the difficulties encountered at a single institution participating in a multicenter drug study and reviews the challenges involved in developing a high-quality randomized controlled study.

Relationship between objective responses in phase I trials and potential efficacy of non-specific cytotoxic investigational new drugs

BACKGROUND

Although the evaluation of new investigational drugs in phase I, II and III trials requires considerable time and patient resources, only a few of these drugs are ultimately established as anticancer drugs.

MATERIALS AND METHODS

We collected papers of phase I trials by a Medline search using the key words 'Neoplasms/Drug Therapy in MeSH' and 'Phase I' for the period from 1976 to 1993. A drug was defined as 'effective' if a regimen including the drug produced positive results in at least one phase III trial. We analyzed the relationship between objective (complete and partial) responses in phase I trials and the effectiveness of agents in phase III trials.

RESULTS

A total of 399 single-agent phase I trials of cytotoxic agents in adult patients with solid tumors were obtained. Further clinical investigation was not recommended in 36 trials (9%) because of severe toxicity. In the remaining 363 trials, 174 drugs were evaluated and the median number of trials for each drug was two (range one to nine). Objective responses were observed in 495 (4.1%) of 12 076 patients, 178 (49%) of 363 trials, and 115 (66%) of 174 drugs. Of the 174 drugs, 48 (28%) were considered to be effective. Percentages of effective drugs rose as the number of responders in phase I trials increased. Logistic regression analyses showed the number of responders to be significantly associated with drug effectiveness [odds ratio = 1.16 (1.06-1.27), P = 0.001 for 174 drugs; odds ratio = 1.16 (1.05-1.28), P = 0.0038 for 363 trials]. Although 10 active drugs failed to produce an objective response in phase I trials, seven of them produced a tumor regression of <50%, and three reportedly produced objective responses in phase I trials conducted before 1975. The numbers of responders among patients with lung, ovarian, breast or colorectal cancer, but not those among patients with lymphoma, melanoma, sarcoma or renal-cell carcinoma, were associated significantly with drug effectiveness against the respective tumors.

CONCLUSIONS

Objective responses observed in phase I trials are important for determining the future development of an anticancer drug.

Assessing the clinical significance of single items relative to summated scores

How many items are needed to measure an individual's quality of life (QOL)? This article describes the strengths and weaknesses of single items and summated scores (from multiple items) as QOL measures. We also address the use of single global measures vs multiple subindices as measures of QOL. The primary themes that recur throughout this article are the relationships between well-defined research objectives, the research setting, and the choice single item vs summated scores to measure QOL. The conceptual framework of the study, the conceptual fit with the measure, and the purpose of the assessment should all be considered when choosing a measure of QOL. No "gold standard" QOL measure can be recommended because no "one size fits all." Single items have the advantage of simplicity at the cost of detail. Multiple-item indices have the advantage of providing a complete profile of QOL component constructs at the cost of increased burden and of asking potentially irrelevant questions. The 2 types of indices are not mutually exclusive and can be used together in a single research study or in the clinical setting.

Randomized, controlled clinical trials in sepsis: has methodological quality improved over time?

OBJECTIVE

To systematically evaluate the methodological quality of randomized clinical trials and to determine whether randomized clinical trials of sepsis improved in methodological quality over time.

DATA SOURCES

Computerized MEDLINE search of articles published in any language from 1966 to 1998 combined with a manual search of bibliographies of published articles and communication with known experts in the field.

STUDY SELECTION

All randomized clinical trials of sepsis, severe sepsis, and septic shock performed in adults and published as full articles.

DATA EXTRACTION

Abstracts of all retrieved records were reviewed and the inclusion criteria were applied. All selected articles were classified into (a) trials designed to detect differences in mortality as the primary end point, or (b) trials focusing on surrogate outcome measures (i.e., physiological or biochemical parameters). All retrieved trials were then graded for methodological quality using an objective grading scheme developed specifically for this study. The data selection and extraction process was carried out independently by two of the authors; any disagreement was resolved by discussion.

DATA SYNTHESIS

Seventy-four randomized clinical trials involving septic patients qualified for inclusion in this study (40 reporting mortality outcomes, 34 reporting other surrogate outcomes). Trials reporting mortality as the primary outcome had significantly higher quality scores compared with trials reporting surrogate outcome measures (29.6 +/- 1.0 vs. 24.3 +/- 0.8, p =.0006). From 1976 to 1998, trial methodology improved significantly over time (an average of 0.36 points per year, p =.021). Mortality outcome trials improved an average of 0.58 points per year (p =.0011) whereas surrogate outcome trials did not demonstrate an improvement in methodological quality over time (p =.249).

CONCLUSION

The methodological limitations identified in this article can help to target further improvement in trial design to enhance the validity of findings from future randomized clinical trials of sepsis.

Willingness to volunteer in future preventive HIV vaccine trials: issues and perspectives from three U.S. communities

This study examined perceived risks, benefits, and desired information related to willingness to volunteer in preventive HIV vaccine trials.

SAMPLE

Purposive sampling was used to select 90 participants among injecting drug users (Philadelphia, PA, U.S.A.); gay men (San Francisco, CA, U.S.A.); and black Americans (Durham, NC, U.S.A.).

METHODS

A qualitative interview guide elicited perceived benefits, risks, and desired information relating to trial participation. Themes were developed from the transcribed texts and from freelists.

RESULTS

Stated willingness to volunteer in a preventive HIV vaccine trial was similar across the three communities. Eight perceived benefits were reported, including self-benefits, altruism, and stopping the spread of AIDS. Seven perceived risks were reported, including negative side effects and vaccine safety issues, contracting HIV from the vaccine, and social stigmatization. Participants voiced the desire for eight types of information about issues relating to trust and confidentiality in the research process, health complications and later assistance, and vaccine trial methodology.

CONCLUSIONS

In this study, many benefits as well as risks of preventive HIV vaccine trial participation were cited. Scientists conducting preventive HIV vaccine trials need to address community perceptions of risks and provide information about the research if trial enrollment is to be diverse and successful.

Clinical drug trials: practical problems of phase III

INTRODUCTION

Phase III randomised clinical trials provide the highest level of evidence to support the superior effectiveness of a new drug or therapy. The main practical problems encountered in the initiation, design, conduct and completion of both investigator-initiated and sponsor-initiated phase III clinical drug trials will be reviewed.

METHODS

A Medline search of clinical drug trials conducted in Singapore as well as journal articles highlighting important methodological considerations and practical problems encountered in phase III clinical trials was performed.

RESULTS

Several phase III randomised clinical trials have been conducted in Singapore which include the investigation of interventions that include tramadol, estradiol patch and colloidal bismuth subcitrate. The main problems encountered in phase III clinical drug trials include difficulties with recruitment of subjects for the study, proper filing of case report forms, special problems in children and the elderly, adequate compensation for adverse events and the adequate archival of documents of the completion of trials. In investigator-initiated trials, careful attention should be given to identifying a suitable study question, choice of study design, sample size calculations and data analysis. In sponsor-initiated trials, a good working relationship with the sponsor is essential and publication terms should be spelt from the onset of the trial.

CONCLUSIONS

Well-planned clinical trials led by a team of competent investigators are essential for the conduct of rigorous sponsor-initiated and investigator-initiated clinical trials.