Intention-to-treat vs. on-treatment analyses of clinical trial data: experience from a study of pyrimethamine in the primary prophylaxis of toxoplasmosis in HIV-infected patients. ANRS 005/ACTG 154 Trial Group

Instrumental variables methods reconcile intention-to-screen effects across pragmatic cancer screening trials

Pragmatic cancer screening trials mimic real-world scenarios in which patients and doctors are the ultimate arbiters of treatment. Intention-to-screen (ITS) analyses of such trials maintain randomization-based apples-to-apples comparisons, but differential adherence (the failure of subjects assigned to screening to get screened) makes ITS effects hard to compare across trials and sites. We show how instrumental variables (IV) methods address the nonadherence challenge in a comparison of estimates from 17 sites in five randomized trials measuring screening effects on colorectal cancer incidence. While adherence rates and ITS estimates vary widely across and within trials, IV estimates of per-protocol screening effects are remarkably consistent. An application of simple IV tools, including graphical analysis and formal statistical tests, shows how differential adherence explains variation in ITS impact. Screening compliers are also shown to have demographic characteristics similar to those of the full trial study sample. These findings argue for the clinical relevance of IV estimates of cancer screening effects.

Adding tiotropium or long-acting β2-agonists to inhaled corticosteroids: Asthma-related exacerbation risk and healthcare resource utilization

Background: Based on current clinical guidelines, long-acting β2-agonists (LABA) are frequently prescribed before long-acting muscarinic antagonists (LAMA) as an add-on to inhaled corticosteroids (ICS) in uncontrolled asthma. However, there is insufficient real-world evidence that supports this therapeutic approach. Objective: The objective was to compare asthma exacerbations and healthcare resource utilization in patients with asthma using the LAMA tiotropium bromide (Tio) or a LABA as an add-on to ICS (ICS + Tio or ICS/LABA) in a real-world setting. Methods: This retrospective, observational study included patients aged ≥12 years with asthma diagnoses identified in a U.S. longitudinal claims database (October 2015 to August 2020). The ICS + Tio and ICS/LABA cohorts were 1:2 propensity score matched for baseline variables. Outcomes were compared in the postmatched cohorts, and the risk of exacerbation was evaluated by using Kaplan-Meier curves. Results: After propensity score matching, there were 633 and 1266 patients in the ICS + Tio and ICS/LABA cohorts, respectively. The proportion of patients who experienced a severe or a moderate-or-severe exacerbation during follow-up was similar between the ICS + Tio versus ICS/LABA cohorts (4% versus 3%, p = 0.472, and 50% versus 45%, p = 0.050, respectively). The mean time to first severe (ICS + Tio 43.8 days versus ICS/LABA 49.4 days, p = 0.758) and moderate-or-severe exacerbation (ICS + Tio 65.8 days versus ICS/LABA 58.9 days, p = 0.474) was not statistically different between cohorts. The treatments had no effect on the risk of severe exacerbation, although it was 36% lower in ICS + Tio users than in ICS/LABA users (hazard ratio 0.64 [95% confidence interval, 0.22-1.84]). All-cause and asthma-related average monthly healthcare resource utilization were comparable between the treatments for hospitalizations and emergency department visits but were significantly greater in the ICS + Tio cohort than in the ICS/LABA cohort for asthma-related outpatient visits (p < 0.0001). Conclusion: This study provides real-world evidence that ICS + Tio may be a valid alternative when ICS/LABA cannot be used as first-line treatment for asthma maintenance therapy.

Association between urate-lowering therapy and cardiovascular events in patients with asymptomatic hyperuricemia

INTRODUCTION/OBJECTIVES

To investigate the role of urate-lowering therapy (ULT) in the prevention of cardiovascular disease (CVD) in patients with asymptomatic hyperuricemia using the Japanese healthcare record database.

METHODS

This retrospective cohort study used data from the JMDC Claims Database, which includes records of medical check-ups and Japanese health insurance claims. Subjects aged at least 18 years with a serum uric acid (sUA) level ≥ 7.0 mg/dL and at least one medical check-up from January 2007 to August 2021 were included in this study. The exposure was any ULT prescription, and the primary outcome included composite CVD outcomes, including coronary artery disease, stroke, and atrial fibrillation. Analysis was performed with a new-user design and overlap weighting to balance the baseline characteristics of the subjects. Cox proportional hazards models were used to investigate the association between ULT and the development of CVD.

RESULTS

In total, 152,166 patients were included in the main analysis before overlap weighting in this retrospective cohort study. The number of subjects in the ULT group was 5,270, and there were 146,896 subjects in the control group. Composite CVD outcomes were observed in a total of 7,703 patients. The risk of developing composite CVD outcomes was not different between the ULT group and the control group (HR: 1.01, 95% CI: 0.89 to 1.13).

CONCLUSIONS

ULT for patients with asymptomatic hyperuricemia did not prevent the development of CVD based on the Japanese claims database. Key points • Among subjects with asymptomatic hyperuricemia, ULT was not associated with a lower risk of CVD • There was no appropriate cutoff for initiating ULT in patients with asymptomatic hyperuricemia • There was no appropriate cutoff as the therapeutic goal of ULT in patients with asymptomatic hyperuricemia.

Using Randomized Controlled Trials to Estimate the Effect of Community Interventions for Childhood Asthma

INTRODUCTION

The Centers for Disease Control and Prevention's Controlling Childhood Asthma and Reducing Emergencies initiative aims to prevent 500,000 emergency department (ED) visits and hospitalizations within 5 years among children with asthma through implementation of evidence-based interventions and policies. Methods are needed for calculating the anticipated effects of planned asthma programs and the estimated effects of existing asthma programs. We describe and illustrate a method of using results from randomized control trials (RCTs) to estimate changes in rates of adverse asthma events (AAEs) that result from expanding access to asthma interventions.

METHODS

We use counterfactual arguments to justify a formula for the expected number of AAEs prevented by a given intervention. This formula employs a current rate of AAEs, a measure of the increase in access to the intervention, and the rate ratio estimated in an RCT.

RESULTS

We justified a formula for estimating the effect of expanding access to asthma interventions. For example, if 20% of patients with asthma in a community with 20,540 annual asthma-related ED visits were offered asthma self-management education, ED visits would decrease by an estimated 1,643; and annual hospitalizations would decrease from 2,639 to 617.

CONCLUSION

Our method draws on the best available evidence from RCTs to estimate effects on rates of AAEs in the community of interest that result from expanding access to asthma interventions.

Effectiveness of a Bundled Intervention Including Adjunctive Corticosteroids on Outcomes of Hospitalized Patients With Community-Acquired Pneumonia: A Stepped-Wedge Randomized Clinical Trial

IMPORTANCE

Community-acquired pneumonia remains a leading cause of hospitalization, mortality, and health care costs worldwide. Randomized clinical trials support the use of adjunctive corticosteroids, early progressive mobilization, antibiotic switching rules, and dietary interventions in improving outcomes. However, it is uncertain whether implementing these interventions will translate into effectiveness under routine health care conditions.

OBJECTIVE

To evaluate the effectiveness of a bundle of evidence-supported treatments under conditions of routine care in a representative population hospitalized for community-acquired pneumonia.

DESIGN, SETTING, AND PARTICIPANTS

A double-blind, stepped-wedge, cluster-randomized clinical trial with 90-day follow-up was conducted between August 1, 2016, and October 29, 2017, in the general internal medicine service at 2 tertiary hospitals in Melbourne, Australia, among a consecutive sample of patients with community-acquired pneumonia. The primary analysis and preparation of results took place between May 14 and November 25, 2018.

INTERVENTIONS

Treating clinical teams were advised to prescribe prednisolone acetate, 50 mg/d, for 7 days (in the absence of any contraindication) and de-escalate from parenteral to oral antibiotics according to standardized criteria. Algorithm-guided early mobilization and malnutrition screening and treatment were also implemented.

MAIN OUTCOMES AND MEASURES

Hospital length of stay, mortality, readmission, and intervention-associated adverse events (eg, gastrointestinal bleeding and hyperglycemia).

RESULTS

A total of 917 patients were screened, and 816 (351 women and 465 men; mean [SD] age, 76 [13] years) were included in the intention-to-treat analysis, with 401 patients receiving the intervention and 415 patients in the control group. An unadjusted geometric mean ratio of 0.95 (95% CI, 0.78-1.16) was observed for the difference in length of stay (days) between the intervention and control groups. Similarly, no significant differences were observed for the secondary outcomes of mortality and readmission, and the results remained unchanged after further adjustment for sex and age. The study reported higher proportions of gastrointestinal bleeding in the intervention group (9 [2.2%]) compared with the controls (3 [0.7%]), with an unadjusted estimated difference in mean proportions of 0.008 (95% CI, 0.005-0.010).

CONCLUSIONS AND RELEVANCE

This bundled intervention including adjunctive corticosteroids demonstrated no evidence of effectiveness and resulted in a higher incidence of gastrointestinal bleeding. Efficacy of individual interventions demonstrated in clinical trials may not necessarily translate into effectiveness when implemented in combination and may even result in net harm.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02835040.

Second-line glucose-lowering drugs added to metformin and the risk of hospitalization for heart failure: A nationwide cohort study

AIM

To compare the risks of hospitalization for heart failure (HHF) associated with sulfonylurea (SU), dipeptidyl peptidase-4 inhibitor (DPP-4i), and thiazolidinedione (TZD) as add-on medications to metformin (MET) therapy using the data of Korean adults with type-2 diabetes from the Korean National Health Insurance database.

METHODS

We identified 98,383 people who received SU (n = 42,683), DPP-4i (n = 50,310), or TZD (n = 5,390) added to initial treatment of MET monotherapy in patients with type-2 diabetes. The main outcome was the hospitalization for HHF. Hazard ratios for HHF by type of second-line glucose-lowering medication were estimated by Cox-proportional hazard models. Sex, age, duration of MET monotherapy, Charlson Comorbidity Index and additional comorbidities, and calendar year were controlled as potential confounders.

RESULTS

The observed numbers (rate per 100,000 person-years) of HHF events were 1,129 (658) for MET+SU users, 710 (455) for MET+DPP-4i users, and 110 (570) for MET+TZD users. Compared to that for MET+SU users (reference group), the adjusted hazard ratios for HHF events were 0.76 (95% confidence interval 0.69-0.84) for MET+DPP-4i users and 0.96 (95% confidence interval 0.79-1.17) for MET+TZD users.

CONCLUSION

DPP-4i as an add-on therapy to MET may lower the risks of HHF compared with SU.

Co-Occurring Trajectory of Mothers' Substance Use and Psychological Control and Children's Behavior Problems: The Effects of a Family Systems Intervention

This study examined the effects of a family systems therapy (Ecologically-Based Family Therapy [EBFT]) on the co-occurring trajectory of mothers' substance use and psychological control, and its association with children's problem behaviors. Participants included 183 mothers with a substance use disorder who had at least one biological child in their care. Mothers were randomly assigned to one of the three intervention conditions: EBFT-home, n = 62; EBFT-office, n = 61; or Women's Health Education, n = 60. Participants were assessed at baseline, 3, 6, 12, and 18 months post-baseline. A dual-trajectory class growth analysis identified three groups of mothers in regard to their change trajectories. The majority of the mothers exhibited a synchronous decrease in substance use and psychological control (n = 107). In all, 46 mothers exhibited a synchronous increase in substance use and psychological control. For the remaining 30 mothers, substance use and psychological control remained stable. Mothers in the family therapy condition were more likely to show reduced substance use and psychological control compared to mothers in the control condition. Moreover, children with mothers who showed decreased substance use and psychological control exhibited lower levels of problem behaviors compared to children with mothers showing increased substance use and psychological control. The findings provide evidence for the effectiveness of family systems therapy, EBFT, in treating mothers' substance use, improving parenting behaviors, and subsequently improving child behavioral outcomes.

Somatostatin Analogues Compared With Placebo and Other Pharmacologic Agents in the Management of Symptoms of Inoperable Malignant Bowel Obstruction: A Systematic Review

CONTEXT

Somatostatin analogues are commonly used to relieve symptoms in malignant bowel obstruction (MBO) but are more expensive than other antisecretory agents.

OBJECTIVES

To evaluate the evidence of effectiveness of somatostatin analogues compared with placebo and/or other pharmacologic agents in relieving vomiting in patients with inoperable MBO.

METHODS

MEDLINE, EMBASE, CINAHL, and The Cochrane Controlled Trials Register databases were systematically searched; reference lists of relevant articles were hand searched. Cochrane risk of bias tool was used.

RESULTS

The search identified 420 unique studies. Seven randomized controlled trials (RCTs) met the inclusion criteria (six octreotide studies and one lanreotide); 220 people administered somatostatin analogues and 207 placebo or hyoscine butylbromide. Three RCTs compared a somatostatin analogue with placebo and four with hyoscine butylbromide. Two adequately powered multicenter RCTs with a low Cochrane risk of bias reported no significant difference between somatostatin analogues and placebo in their primary end points. Four RCTs with a high/unclear Cochrane risk of bias reported that somatostatin analogues were more effective than hyoscine butylbromide in reducing vomiting.

CONCLUSION

There is low-level evidence of benefit with somatostatin analogues in the symptomatic treatment of MBO. However, high-level evidence from trials with low risk of bias found no benefit of somatostatin analogues for their primary outcome. There is debate regarding the clinically relevant study end point for symptom control in MBO and when it should be measured. The role of somatostatin analogues in this clinical situation requires further adequately powered, well-designed trials with agreed clinically important end points and measures.

Bromelain and cardiovascular risk factors in diabetes: An exploratory randomized, placebo controlled, double blind clinical trial

OBJECTIVE

To assess whether the dietary supplement (bromelain) has the potential to reduce plasma fibrinogen and other cardiovascular disease (CVD) risk factors in patients with diabetes.

METHODS

This randomized placebo controlled, double blind, parallel design, efficacy study was carried out in China and investigated the effect of 12 weeks of bromelain (1,050 mg/day) on plasma fibrinogen. This randomized controlled trial (RCT) recruited 68 Chinese diabetic patients [32 males and 36 females; Han origin, mean age of 61.26 years (standard deviation (SD), 12.62 years)] with at least one CVD risk factor. Patients were randomized into either bromelain or placebo group. While bromelain group received bromelain capsule, the placebo group received placebo capsule which consisted inert ingredient and has no treatment effect. Subjects were required to take 1,050 mg (3×350 mg) of either bromelain or starch-filled placebo capsules, two to be taken (2×350 mg) after breakfast and another (350 mg) after dinner, daily for 12 weeks. Plasma fibrinogen, CVD risk factors and anthropometric indicators were determined at baseline and at 12 weeks.

RESULTS

The change in the fibrinogen level in the bromelain group at the end of the study showed a mean reduction of 0.13 g/L (standard deviation (SD) 0.86g/L) compared with the mean reduction of 0.36 g/L (SD 0.96 g/L) for the placebo group. However, there was no significant difference in the mean change in fibrinogen between the placebo and bromelain groups (mean difference=0.23g/L (SD 0.22 g/L), =0.291). Similarly, the difference in mean change in other CVD risk factors (blood lipids, blood pressure), blood glucose, C-reactive protein and anthropometric measures between the bromelain and placebo groups was also not statistically significant. Statistical differences in fibrinogen between bromelain and placebo groups before the trial despite randomization may have influenced the results of this study.

CONCLUSION

This RCT failed to show a beneficial effect in reducing fibrinogen or influencing other selected CVD risk factors but suggests other avenues for subsequent research on bromelain.

A commentary on randomized clinical trials: How to produce them with a good level of evidence

Randomized clinical trial (RCT) is the gold standard study for the evaluation of health interventions and is considered the second level of evidence for clinical decision making. However, the quality of the evidence produced by these studies is dependent on the methodological rigor employed at every stage of their execution. The purpose of randomization is to create groups that are comparable independent of any known or unknown potential confounding factor. A critical evaluation of the literature reveals that, for many years, RCTs have been developed based on inaccurate methodological criteria, and empirical evidence began to accumulate. Thus, guidelines were developed to assist authors, reviewers, and editors in the task of developing and assessing the methodological consistency of this type of study. The objective of this article is to review key aspects to design a good-quality RCT, supporting the scientific community in the production of reliable evidence and favoring clinical decision making to allow the patient to receive the best health care.

Analysis and reporting of stepped wedge randomised controlled trials: synthesis and critical appraisal of published studies, 2010 to 2014

Background

Stepped wedge cluster randomised trials introduce interventions to groups of clusters in a random order and have been used to evaluate interventions for health and wellbeing. Standardised guidance for reporting stepped wedge trials is currently absent, and a range of potential analytic approaches have been described.

Methods

We systematically identified and reviewed recently published (2010 to 2014) analyses of stepped wedge trials. We extracted data and described the range of reporting and analysis approaches taken across all studies. We critically appraised the strategy described by three trials chosen to reflect a range of design characteristics.

Results

Ten reports of completed analyses were identified. Reporting varied: seven of the studies included a CONSORT diagram, and only five also included a diagram of the intervention rollout. Seven assessed the balance achieved by randomisation, and there was considerable heterogeneity among the approaches used. Only six reported the trend in the outcome over time. All used both ‘horizontal’ and ‘vertical’ information to estimate the intervention effect: eight adjusted for time with a fixed effect, one used time as a condition using a Cox proportional hazards model, and one did not account for time trends. The majority used simple random effects to account for clustering and repeat measures, assuming a common intervention effect across clusters. Outcome data from before and after the rollout period were often included in the primary analysis. Potential lags in the outcome response to the intervention were rarely investigated. We use three case studies to illustrate different approaches to analysis and reporting.

Conclusions

There is considerable heterogeneity in the reporting of stepped wedge cluster randomised trials. Correct specification of the time-trend underlies the validity of the analytical approaches. The possibility that intervention effects vary by cluster or over time should be considered. Further work should be done to standardise the reporting of the design, attrition, balance, and time-trends in stepped wedge trials.

Oncological outcome of malignant colonic obstruction in the Dutch Stent-In 2 trial

BACKGROUND

The Stent-In 2 trial randomized patients with malignant colonic obstruction to emergency surgery or stent placement as a bridge to elective surgery. The aim of this study was to compare the oncological outcomes.

METHODS

Disease recurrence, and disease-free, disease-specific and overall survival were evaluated, including a subgroup analysis of patients with a stent- or guidewire-related perforation.

RESULTS

Of 98 patients included in the original Stent-In 2 trial, patients with benign (16) or incurable (23) disease were excluded from this study, along with a patient who had withdrawn from the trial. Of the remaining 58 patients, 32 were randomized to emergency surgery (31 resection, 1 stoma only) and 26 to stenting. Unsuccessful stenting required emergency surgery in six patients owing to wire or stent perforation. Locoregional or distant disease recurrence developed in nine of 32 patients in the emergency surgery group and 13 of 26 in the stent group. Disease-free survival was worse in the subgroup with stent- or guidewire-related perforation. Five of six patients in this subgroup developed a recurrence, compared with nine of 32 in the emergency surgery group and eight of 20 who had unperforated stenting.

CONCLUSION

Stent placement for malignant colonic obstruction was associated with a risk of recurrence in this trial, but the numbers are small. There is not enough evidence to refute the approach strongly.

REGISTRATION NUMBER

ISRCTN46462267 ( http://www.controlled-trials.com).

An application of the Complier Average Causal Effect analysis to examine the effects of a family intervention in reducing illicit drug use among high-risk Hispanic adolescents

The Complier Average Causal Effect (CACE) method has been increasingly used in prevention research to provide more accurate causal intervention effect estimates in the presence of noncompliance. The purpose of this study was to provide an applied demonstration of the CACE analytic approach to evaluate the relative effects of a family-based prevention intervention, Familias Unidas, in preventing/reducing illicit drug use for those participants who received the intended dosage. This study is a secondary data analysis of a randomized controlled trial designed to evaluate the relative efficacy of Familias Unidas with high-risk Hispanic youth. A total of 242 high-risk Hispanic youth aged 12-17 years and their primary caregivers were randomized to either Familias Unidas or Community Practice and assessed at baseline, 6 months and 12 months postbaseline. CACE models were estimated with a finite growth mixture model. Predictors of engagement were included in the CACE model. Findings indicate that, relative to the intent-to-treat (ITT) analytic approach, the CACE analytic approach yielded stronger intervention effects among both initially engaged and overall engaged participants. The CACE analytic approach may be particularly helpful for studies involving parent/family-centered interventions given that participants may not receive the intended dosage. Future studies should consider implementing the CACE analysis in addition to ITT analysis when examining the effects of family-based prevention programs to determine whether, and the extent to which, the CACE analysis has more power to uncover intervention effects.

Influence of foot orthotics upon duration of effects of spinal manipulation in chronic back pain patients: a randomized clinical trial

OBJECTIVE

The purpose of this study was to investigate the effects of 4 weeks of custom foot orthotics on pain, disability, recurrence of spinal fixation, and muscle dysfunction in adult low back pain patients receiving limited chiropractic care.

METHODS

Adult volunteers with low back pain of greater than or equal to 1 month's duration were randomized to receive custom orthotics (group A) or a flat insole sham (group B) with limited chiropractic care in 5 visits over 4 weeks. Primary outcome measures are as follows: Quadruple Numerical Pain Rating Scale (for back), the Roland-Morris Disability Questionnaire, the number of muscles grade 4 or lower on manual muscle testing, and the number of spinal fixations detected by motion palpation and vertebral challenge at intake (B1), 2 weeks later before treatment began and orthotic use was initiated (B2) and before each subsequent treatment at approximately days 3, 10, 17, and 24 after B2. Secondary outcome measures are correlations of all primary outcomes.

RESULTS

Both groups improved on all Numerical Pain Rating Scale, Roland-Morris Disability Questionnaire, and the number of muscles from intake (B1) to final visit. Only group B yielded significant improvements in the number of spinal fixations. No outcome measures showed statistical difference between groups at any time point; however, those who wore custom orthotics longer each day showed trends toward greater improvements in some outcome measures.

CONCLUSIONS

Both groups improved with chiropractic care including spinal manipulation; however, there were no statistical differences shown between sham and custom orthotic groups. Future studies should formally measure the time that orthotics or shams are worn in a weight-bearing capacity each day.

Opening the "Black Box": family check-up intervention effects on self-regulation that prevents growth in problem behavior and substance use

Family-school interventions are a well-established method for preventing and remediating behavior problems in at-risk youth, yet the mechanisms of change underlying their effectiveness are often overlooked or poorly understood. The Family Check-Up (FCU), a school-based, family-centered intervention, has been consistently associated with reductions in youth antisocial behavior, deviant peer group affiliation, and substance use. The purpose of this study was to explore proximal changes in student-level behavior that accounts for links between implementation of the FCU and changes in youth problem behavior. Data were drawn from a randomized controlled trial study of the efficacy of the FCU among 593 ethnically diverse middle school students followed longitudinally from 6th through 8th grades. Latent growth curve analyses revealed that random assignment to the FCU intervention condition was related to increased mean levels of students' self-regulation from 6th to 7th grades, which in turn reduced the risk for growth in antisocial behavior, involvement with deviant peers, and alcohol, tobacco, and marijuana use through the 8th grade. Overall, these findings highlight the robust implications of self-regulation as a proximal target for family-centered interventions.

Randomised controlled trials and clinical maternity care: moving on from intention-to-treat and other simplistic analyses of efficacy

BACKGROUND

The obstetrical literature is dominated by Randomised Controlled Trials (RCTs), with the vast majority being analysed using an intention-to-treat (ITT) approach. Whilst this approach may reflect well the consequence of assignment to therapy and hence the 'trialists'perspective', it may fail to address the consequence of actually receiving therapy (the patient's perspective).

DISCUSSION

This review questions the ubiquitous adherence to the ITT approach, and gives examples of where this may have misled the maternity care professions. It gives an overview of techniques to overcome potential deficiencies in result presentation, using method effectiveness models such as 'Per Protocol' (PP) or 'As-Treated' (AT) that may give more accurate clinical meaning to the presentation of obstetrical results. It then proceeds to cover the added benefits, considerations and potential pitfalls of the use of Instrumental Variable (IV) models in order to better reflect the clinical context.

SUMMARY

While ITT may achieve statistical purity, it frequently fails to address the true clinical or patient's perspective. Though more complex and potentially beset by problems of their own, alternative methods of result presentation may better serve the latter aim. Each of the other methods may rely on untestable assumptions and therefore it is wisest that study results are presented in multiple formats to allow for informed reader evaluation.

Intervention dose estimation in health promotion programmes: a framework and a tool. Application to the diet and physical activity promotion PRALIMAP trial

Background

Although the outcomes of health promotion and prevention programmes may depend on the level of intervention, studies and trials often fail to take it into account. The objective of this work was to develop a framework within which to consider the implementation of interventions, and to propose a tool with which to measure the quantity and the quality of activities, whether planned or not, relevant to the intervention under investigation. The framework and the tool were applied to data from the diet and physical activity promotion PRALIMAP trial.

Methods

A framework allowing for calculation of an intervention dose in any health promotion programme was developed. A literature reviews revealed several relevant concepts that were considered in greater detail by a multidisciplinary working group. A method was devised with which to calculate the dose of intervention planned and that is actually received (programme-driven activities dose), as well as the amount of non-planned intervention (non-programme-driven activities dose).

Results

Indicators cover the roles of all those involved (supervisors, anchor personnel as receivers and providers, targets), in each intervention-related groups (IRG: basic setting in which a given intervention is planned by the programme and may differ in implementation level) and for every intervention period. All indicators are described according to two domains (delivery, participation) in two declensions (quantity and quality). Application to PRALIMAP data revealed important inter- and intra-IRG variability in intervention dose.

Conclusions

A literature analysis shows that the terminology in this area is not yet consolidated and that research is ongoing. The present work provides a methodological framework by specifying concepts, by defining new constructs and by developing multiple information synthesis methods which must be introduced from the programme's conception. Application to PRALIMAP underlined the feasibility of measuring the implementation level. The framework and the tool can be used in any complex programme evaluation. The intervention doses obtained could be particularly useful in comparative trials.

Trial registration

PRALIMAP is registered at ClinicalTrials.gov under NCT00814554

Balance and agility training does not always decrease lower limb injury risks: a cluster-randomised controlled trial

The objective of this study was to examine the effects on lower limb injury rates of adding structured balance and agility exercises to the 80-day basic training programme of army recruits. A blocked (stratified), cluster-randomised controlled trial was employed, with one intervention group (IG) and one control group (CG), in which 732 male and 47 female army recruits from the Australian Army Recruit Training Centre participated through to analysis. The IG performed specified balance and agility exercises in addition to normal physical training. The incidence of lower limb injury during basic training was used to measure effect. Analysis, which adhered to recommendations for this type of trial, used a weighted paired t-test based on the empirical logistic transform of the crude event rates. The intervention had no statistically significant effect on lower limb injury incidence (RR = 1.25, 95% CI 0.97-1.53, 90% CI 1.04-1.47), on knee and ankle injury incidence (RR = 1.08, 95% CI 0.83-1.38), and on knee and ankle ligament injury incidence (RR = 0.98, 95% CI 0.64-1.47). We conclude that the intervention, implemented in this fashion, is possibly harmful, with our best estimate of effect being a 25% increase in lower limb injury incidence rates. This type of structured balance and agility training added to normal military recruit physical training did not significantly reduce lower limb, knee and ankle, or knee and ankle ligament injury rates. Caution needs to be used when adding elements to training programmes with the aim of reducing injury, as fatigue associated with the addition may actually raise injury risk.

Modified intention to treat reporting in randomised controlled trials: systematic review

OBJECTIVES

To determine the incidence and characteristics of randomised controlled trials that report using the modified intention to treat approach, and how the approach is described.

DESIGN

Systematic review.

DATA SOURCES

PubMed, Embase, Cochrane central register of controlled trials, ISI Web of Knowledge, Ovid, HighWire Press, Science-Direct, Ingenta, Medscape, BioMed Central, Springer, and Wiley, from inception to December 2006.

MAIN OUTCOME MEASURES

Incidence of trials in which use of modified intention to treat was reported, and how the approach was described (classified according to the type and number of deviations from the intention to treat approach).

RESULTS

475 randomised controlled trials reported use of a modified intention to treat analysis. Of these, 76 (16%) were published in five highly cited general medical journals. The incidence of all trials that reported use of modified intention to treat published in journals indexed in Medline increased from 0.006% in 1982-6 to 0.5% in 2002-6 (P<0.001 for linear trend). When the description of the modified intention to treat was examined in each trial, 192 (40%) reported one type of deviation from the intention to treat approach, 261 (55%) reported two or more types, and 22 (5%) did not describe any type. In 266 (56%) of the trials the deviation was related to the treatment received, in 196 (41%) to a post baseline assessment, in 118 (25%) to a baseline assessment, in 108 (23%) to a target condition, and in 23 (5%) to follow-up. Post-randomisation exclusions occurred in 380 (80%) trials. The results reported by 270 of the 352 (77%) superiority trials favoured the drug under investigation. All of the 123 trials using equivalence or non-inferiority methods to investigate interventions reported results that favoured their assumptions.

CONCLUSIONS

Randomised controlled trials that report using a modified intention to treat are increasingly being published in the medical literature. The descriptions of such an approach were ambiguous, and may cover any type of descriptions for exclusion, such as missing data and deviation from protocol. Explicit statements about post-randomisation exclusions should replace the ambiguous terminology of modified intention to treat.

Methodological issues in the use of composite endpoints in clinical trials: examples from the HIV field

BACKGROUND

In many fields, the choice of a primary endpoint for a trial is not always the ultimate clinical endpoint of interest, but rather some surrogate endpoint believed to be relevant for predicting the effect of the intervention on the clinical endpoint. The classic example of such a field is clinical HIV treatment research, where a variety of primary endpoints are used to evaluate the efficacy of new antiretroviral drugs or new combinations of existing drugs. The choice of endpoint reflects either the goal of therapy as recommended by treatment guidelines (e.g. rapid virological suppression) or the licensing requirements of official drug approval organizations (e.g. time to loss of virological response [TLOVR]).

PURPOSE

To review the diversity of endpoints used in recent clinical trials in HIV infection and highlight the methodological issues.

METHODS

We identified articles relating to antiretroviral therapy by searching PubMed and through hand searches of relevant conference abstracts. We restricted the search to randomized controlled trials conducted in HIV-infected adults published/presented from January 2005 until March 2008.

RESULTS

We identified 28 trials in antiretroviral-naive patients (i.e. patients who were starting antiretroviral therapy for the first time at the time of randomization) and 23 trials in antiretroviral-experienced patients. Most trials were performed for purposes of drug licensing, but others were focused on strategies of using approved drugs. Most trials (40 of 51) used a composite primary endpoint (TLOVR in 13). Of note, 22 of these 40 studies reported that they had used a purely virological efficacy endpoint, but the primary endpoint was actually a composite one due to the way in which missing data and treatment switches were considered as failures.

LIMITATIONS

Examples are restricted to HIV clinical trials.

CONCLUSIONS

Whilst most current HIV clinical trials use composite primary endpoints, there are substantial differences in the components that make up these endpoints. In HIV and other fields where precise definitions are variable, guidelines for standardization of definition and reporting would greatly improve the ability to compare trial results.

Surgeon equipoise as an inclusion criterion for the evaluation of nonoperative versus operative treatment of thoracolumbar spinal injuries

BACKGROUND CONTEXT

Prospective studies have failed to demonstrate the superiority of either operative or nonoperative treatment of thoracolumbar fractures. Similar to other surgical fields, research has been limited by the variability in surgical interventions, difficult recruitment, infrequent pathology, and the urgency of interventions.

PURPOSE

To outline factors precluding randomized controlled trials in spinal fractures research, and describe a novel methodology that seeks to improve on the design of observational studies.

STUDY DESIGN/SETTING

A preliminary report describing an observational study design with clinical equipoise as an inclusion criterion. The proposed methodology is a cohort study with head-to-head comparison of operative and nonoperative treatment regimens in an expertise-based trial fashion. Patients are selected retrospectively by an expert panel and clinical outcomes are assessed to compare competing treatment regimens. Surgeon equipoise served as an inclusion criterion.

PATIENT SAMPLE

Patients with closed or open thoracolumbar spinal fracture with or without neurological impairment, presenting to one of two different trauma centers between 1991 and 2005 (N = 760).

OUTCOME MEASURES

Homogeneity of baseline clinical and demographic data and distribution of prognostic risk factors between the operative and the nonoperative cohort.

METHODS

Patients treated for spine fractures at two University hospitals practicing opposing methods of fracture intervention were identified by medical diagnosis code searches (n = 760). A panel of spine treatment experts, blinded to the treatment received clinically has assessed each case retrospectively. Patients were included in the study when there was disagreement on the preferred treatment, that is, operative or nonoperative treatment of the injury. Baseline and initial data of a study evaluating nonoperative versus operative spinal fracture treatment are presented.

RESULTS

One hundred and ninety patients were included in the study accounting for a panel discordance rate of 29%. The distribution of baseline characteristics and demographics of the study populations were equal across the parallel cohorts enrolled in the study, that is, no differences in prognostic factors were observed.

CONCLUSIONS

The use of clinical equipoise as an inclusion criterion in comparative studies may be used to avoid selection bias. Using multivariate analysis of retrospectively assembled parallel cohorts, a valid comparison of operative and nonoperative spine fracture treatment strategies and their outcomes is possible.

Discordance between reported intention-to-treat and per protocol analyses

OBJECTIVE

To quantify the degree of disagreement between the two most popular methods for dealing with missing data: intention to treat (ITT) and per protocol (PP).

STUDY DESIGN AND SETTING

We performed a systematic review of randomized two-armed clinical trials (CTs) published between 2001 and 2003, abstracted in PubMed and reporting both the ITT and PP analyses on a primary binary endpoint, out of which 74 papers were finally selected. The treatment effect of each CT was measured by the odds ratio, and the disagreement between them was quantified by the Bland-Altman method.

RESULTS

On average, the PP estimator provides greater values Log(e)ORPP=1 x 25.Log(e)ORITT, (95% CI: 1.15, 1.35) than the corresponding ITT estimator, although the limits of concordance showed that the ratio between the two estimators varies greatly from 0.39 up to 2.53.

CONCLUSION

These results confirm that missing values may cause both systematic and unpredictable bias in CTs. Further efforts should be made to minimize protocol deviations and to use better statistical methods to highlight the drawbacks of missing information. In the presence of protocol deviations, the conclusion of a CT cannot rest on the single reporting of either the ITT or the PP approach alone.

Long-Term Effect of Xylitol Gum Use on Mutans Streptococci in Adults

Many studies have shown the effects of chewing xylitol gum on mutans streptococci (MS) over short- and long-term periods in children; however, few studies have addressed long-term periods in adults. The objective of this investigation was to examine for 6 months the effects of chewing xylitol gum on MS in saliva and plaque in 127 adults (mean age 28.0 years). The participants were assigned to three groups according to gum type, in part taking preference for flavor into account and in part at random: xylitol (XYL), maltitol (MAL) and control (CR); 33, 34 and 27 subjects in each group, respectively, completed the trial. Daily gum use of the XYL and MAL groups was 7.9 and 7.1 g, respectively. MS levels, which declined significantly in saliva (p < 0.05) and plaque (p < 0.001) in the XYL group after 6 months, exhibited a significant increase in plaque in the MAL group (p < 0.001). Differences in relative changes of MS levels in plaque during the experimental period were significant between the XYL group and the CR (p < 0.05) and MAL groups (p < 0.001). Differences in relative change of amount of plaque during the experimental period were not statistically significant between the groups. The present study demonstrated that chewing xylitol gum for 6 months continued to inhibit the growth of mutans streptococci in adults.

Dynamic wait-listed designs for randomized trials: new designs for prevention of youth suicide

BACKGROUND

The traditional wait-listed design, where half are randomly assigned to receive the intervention early and half are randomly assigned to receive it later, is often acceptable to communities who would not be comfortable with a no-treatment group. As such this traditional wait-listed design provides an excellent opportunity to evaluate short-term impact of an intervention. We introduce a new class of wait-listed designs for conducting randomized experiments where all subjects receive the intervention, and the timing of the intervention is randomly assigned. We use the term "dynamic wait-listed designs" to describe this new class.

PURPOSE

This paper examines a new class of statistical designs where random assignment to intervention condition occurs at multiple times in a trial. As an extension of a traditional wait-listed design, this dynamic design allows all subjects to receive the intervention at a random time. Motivated by our search for increased statistical power in an ongoing school-based trial that is testing a program of gatekeeper training to identify suicidal youth and refer them to treatment, this new design class is especially useful when the primary outcome is a count or rate of occurrence, such as suicidal behavior, whose rate can fluctuate over time due to uncontrolled factors.

METHODS

Statistical power is computed for various dynamic wait-listed designs under conditions where the underlying rate of occurrence is allowed to vary nonsystematically. We also present as an example a large ongoing trial to evaluate a gatekeeper training suicide prevention program in 32 schools which we initially began as a classic randomized wait-listed design. The primary outcome of interest in this study is the count of the number of children who are identified by the school system as having suicidal thoughts or behaviors who are then validated as being suicidal by mental health professionals in the community.

RESULTS

A general result shows that dynamic wait-listed designs always have higher statistical power over a traditional wait-listed design. This power increase can be substantial. Efficiency gains of 33% are easy to obtain for situations where the intervention has a small effect and the variation in rate across time is quite high. When the rate variation for an outcome is very low or the intervention effect is large, efficiency gains approach 100%. A small increase in the number of times where random assignment occurs from 2 - for the standard wait-listed design, to say 4 can provide a large reduction in variance. Efficiency gains can also be high when converting standard wait-listed design to a dynamic one half-way into the study.

LIMITATIONS

As with all wait-listed designs, dynamic wait-listed designs can only be used to evaluate short-term impact. Since all subjects eventually receive the intervention, no comparison can be made after the end of the random assignment period. The statistical power benefits are primarily limited to outcomes that can be treated as count or time to event data.

CONCLUSIONS

A dynamic design randomly assigns units - either individuals or groups - to start the intervention at varying times during the course of the study. This design is useful in testing interventions that screen for new or existing cases, as well as testing the scalability of interventions as they are disseminated or expanded system wide. They can improve on the traditional wait-listed design both in terms of statistical power and robustness in the presence of exogenous factors. This paper demonstrates that such designs yield smaller standard errors and can achieve higher statistical power than that of a standard wait-listed design. Just as important, dynamic designs can also help reduce the logistical challenges of implementing an intervention on a wide scale. When the intervention requires that significant training resources be allocated throughout the study, the dynamic wait-listed design is likely to increase the rate of training and lead to a higher level of program implementation.

The trials and tribulations of intrapartum studies

OBJECTIVE

To review the reporting of randomised controlled trials for intrapartum interventions.

METHODS

This was a literature search addressing the period from the publication of the CONSORT statement i.e. 1996-2002. Databases searched: Medline and CINAHL. Search terms: pregnancy, low-risk, normal, intrapartum, labour and labor.

INCLUSION CRITERIA

randomised controlled trials reported in English which involved women experiencing: normal or 'low risk' pregnancy; intrapartum interventions; women who had a spontaneous onset of labour.

DATA EXTRACTION

timing of consent and randomisation, proportion of eligible women recruited, 'losses' to the study. Included Studies fourteen published and one unpublished study that fitted the inclusion criteria were identified. Three studies were subsequently excluded because of a lack of information about the method and a further study was excluded due to its small sample size.

FINDINGS

Three strategies for recruitment and randomisation for intrapartum studies were reported in the literature: antenatal recruitment and randomisation; consent and randomisation conducted on admission in labour or at the time of the intervention; staged recruitment and randomisation, which may be two- or three-staged. Different study designs have done much to improve the appearance of intrapartum studies and reduce post-randomisation losses. However, the problem of bias in RCTs is not limited to attrition alone and these designs may simply be moving the problem to an earlier stage in the study resulting in selection bias and limiting generalisability.

CONCLUSIONS

The importance of accurate documentation of numbers at all stages in the research process is highlighted, in particular the number of eligible people not recruited, to allow the reader to assess the generalisability of the study.

Intention-to-treat approach to data from randomized controlled trials: a sensitivity analysis

The intention-to-treat (ITT) approach to randomized controlled trials analyzes data on the basis of treatment assignment, not treatment receipt. Alternative approaches make comparisons according to the treatment received at the end of the trial (as-treated analysis) or using only subjects who did not deviate from the assigned treatment (adherers-only analysis). Using a sensitivity analysis on data for a hypothetical trial, we compare these different analytical approaches in the context of two common protocol deviations: loss to follow-up and switching across treatments. In each case, two rates of deviation are considered: 10% and 30%. The analysis shows that biased estimates of effect may occur when deviation is nonrandom, when a large percentage of participants switch treatments or are lost to follow-up, and when the method of estimating missing values accounts inadequately for the process causing loss to follow-up. In general, ITT analysis attenuates between-group effects. Trialists should use sensitivity analyses on their data and should compare the characteristics of participants who do and those who do not deviate from the trial protocol. The ITT approach is not a remedy for unsound design, and imputation of missing values is not a substitute for complete, good quality data.

Community-based alcohol counselling: a randomized clinical trial

AIMS

To examine the effectiveness of a brief intervention (BI) and cognitive behaviour therapy (CBT) for alcohol abuse.

DESIGN

A randomized trial with clients randomized within counsellors.

SETTING

Community-based drug and alcohol counselling in Australia.

PARTICIPANTS

Of all new clients attending counselling. 869 (82%) completed a computerized assessment at their first consultation. Four hundred and twenty-one (48%) were defined as eligible, of whom 295 (70%) consented and were allocated randomly to an intervention. Of these, 13 3 (45%) were followed-up at 6 months post-test.

INTERVENTIONS

BI comprised the elements identified by the acronym FRAMES:feedback, responsibility, advice, menu, empathy, self-efficacy. Face-to-face counselling time was not to exceed 90 minutes. CBT comprised six consecutive weekly sessions: introduction: cravings and urges; managing crises; saying 'no' and solving problems: emergencies and lapses: and maintenance. Total face-to-face counselling time was 270 minutes (six 45-minute sessions).

MEASUREMENTS

Treatment outcomes are measured in terms of counsellor compliance, client satisfaction, weekly and binge consumption, alcohol-related problems, the AUDIT questionnaire and cost-effectiveness.

FINDINGS

When analysed on an intention-to-treat basis and for those followed-up. treatment outcomes between BI and CBT were not statistically significantly different at pre- or post-test, whether considered as continuous or categorical variables. BI was statistically significantly more cost-effective than CBT and there was no difference between them in clients' reported levels of satisfaction.

CONCLUSION

For low-dependence alcohol abuse in community settings, BI may be the treatment of choice.

Study control, violators, inclusion criteria and defining explanatory and pragmatic trials

Important differences between explanatory and pragmatic studies were originally argued by Schwartz and Lellouch. Three important differences between the two types of study involve study control, study violators and inclusion criteria. It was originally argued that explanatory studies are highly controlled, and pragmatic studies may be looser and more like 'real life'. It was argued that an explanatory study should only analyse those receiving treatment, and a pragmatic study would analyse all randomized patients. Explanatory trials are said to use homogeneous groups, and pragmatic studies have less selection (better generalizability). Some suggestions are put forward to update the original distinctions between these two attitudes for future study design. Poor study control is undesirable (but might be necessary) and should not be welcomed as pragmatic. The intention-to-treat strategy is now considered as standard for nearly all trials. Homogeneity is a red herring for studies in humans. Inclusion criteria should be minimized and they should not be used to justify claims of representativeness. Routine criticism of randomized controlled trials for being unrepresentative is unwarranted. We should accept that most trials in humans are 'explanatory'. The division line should be moved, so that pragmatic studies are in the domain of non-therapeutics and complex treatments.

Analysis of Virological Efficacy in Trials of Antiretroviral Regimens: Drawbacks of Not Including Viral Load Measurements after Premature Discontinuation of Therapy

Objectives

To compare two analytic approaches to assess the virological effect of HAART according to the intention-to-treat (ITT) principle.

Material

Data from 2318 patients enrolled in 10 randomised clinical trials (RCTs) and from 3091 patients followed in an observation cohort (EuroSIDA) starting their first HAART regimen.

Methods

Two classifications of defining virological response 48 weeks after starting the therapy to be evaluated were compared: 1) only patients remaining on the therapy and having a plasma viral load (pVL) below a given cut-off level at week 48 were classified as responders (ITT/s=f); and 2) patients with a pVL below a given cut-off at week 48 whether they remained on initial assigned therapy or switched therapy were responders (ITT/s incl). In both analyses, patients with missing data at week 48 were classified as failures (i.e., non-responders).

Results

According to ITT/s=f, 22–70% of the patients starting a HAART regimen in a RCT experienced a virological response at week 48. Only two RCTs had complete follow-up data ( n=424): between 29 and 62% achieved a virological response at week 48 in the six treatment arms evaluated in the studies according to ITT/s=f, and 41–72% according to ITT/s incl. Among those who discontinued the therapy to be evaluated in these two trials, 13–45% (cohort: 39–74%) subsequently experienced a virological response at week 48. The subsequent response rates were associated with the reason for discontinuation (toxicity versus confirmed virological failure: 63 vs 33%), varied largely across regimens and were not associated with the discontinuation rate.

Conclusions

Discontinuation of follow-up at switch from the therapy to be evaluated remains common in anti-retroviral treatment trials, but leads to an imprecise and incomplete assessment of the intrinsic effect of a given regimen. Complete follow-up of all patients should be encouraged strongly as this will allow for several complementary analytic approaches and a focus on optimal treatment strategies rather than specific regimens.

Efficacy of a preventive intervention for youths living with HIV

OBJECTIVES

HIV transmission behaviors and health practices of HIV-infected youths were examined over a period of 15 months after they received a preventive intervention.

METHODS

HIV-infected youths aged 13 to 24 years (n = 310; 27% African American, 37% Latino) were assigned by small cohort to (1) a 2-module ("Stay Healthy" and "Act Safe") intervention totaling 23 sessions or (2) a control condition. Among those in the intervention condition, 73% attended at least 1 session.

RESULTS

Subsequent to the "Stay Healthy" module, number of positive lifestyle changes and active coping styles increased more often among females who attended the intervention condition than among those in the control condition. Social support coping also increased significantly among males and females attending the intervention condition compared with those attending the control condition. Following the "Act Safe" module, youths who attended the intervention condition reported 82% fewer unprotected sexual acts, 45% fewer sexual partners, 50% fewer HIV-negative sexual partners, and 31% less substance use, on a weighted index, than those in the control condition.

CONCLUSIONS

Prevention programs can effectively reduce risk acts among HIV-infected youths. Alternative formats need to be identified for delivering interventions (e.g., telephone groups, individual sessions).

A randomized trial of preexercise stretching for prevention of lower-limb injury

PURPOSE

This study investigated the effect of muscle stretching during warm-up on the risk of exercise-related injury.

METHODS

1538 male army recruits were randomly allocated to stretch or control groups. During the ensuing 12 wk of training, both groups performed active warm-up exercises before physical training sessions. In addition, the stretch group performed one 20-s static stretch under supervision for each of six major leg muscle groups during every warm-up. The control group did not stretch.

RESULTS

333 lower-limb injuries were recorded during the training period, including 214 soft-tissue injuries. There were 158 injuries in the stretch group and 175 in the control group. There was no significant effect of preexercise stretching on all-injuries risk (hazard ratio [HR] = 0.95, 95% CI 0.77-1.18), soft-tissue injury risk (HR = 0.83, 95% CI 0.63-1.09), or bone injury risk (HR = 1.22, 95% CI 0.86-1.76). Fitness (20-m progressive shuttle run test score), age, and enlistment date all significantly predicted injury risk (P < 0.01 for each), but height, weight, and body mass index did not.

CONCLUSION

A typical muscle stretching protocol performed during preexercise warm-ups does not produce clinically meaningful reductions in risk of exercise-related injury in army recruits. Fitness may be an important, modifiable risk factor.

Efavirenz plus zidovudine and lamivudine, efavirenz plus indinavir, and indinavir plus zidovudine and lamivudine in the treatment of HIV-1 infection in adults. Study 006 Team

BACKGROUND

Efavirenz is a nonnucleoside reverse-transcriptase inhibitor of human immunodeficiency virus type 1 (HIV-1). We compared two regimens containing efavirenz, one with a protease inhibitor and the other with two nucleoside reverse-transcriptase inhibitors, with a standard three-drug regimen.

METHODS

The study subjects were 450 patients who had not previously been treated with lamivudine or any nonnucleoside reverse-transcriptase inhibitor or protease inhibitor. In this open-label study, patients were randomly assigned to one of three regimens: efavirenz (600 mg daily) plus zidovudine (300 mg twice daily) and lamivudine (150 mg twice daily); the protease inhibitor indinavir (800 mg every eight hours) plus zidovudine and lamivudine; or efavirenz plus indinavir (1000 mg every eight hours).

RESULTS

Suppression of plasma HIV-1 RNA to undetectable levels was achieved in more patients in the group given efavirenz plus nucleoside reverse-transcriptase inhibitors than in the group given indinavir plus nucleoside reverse-transcriptase inhibitors (70 percent vs. 48 percent, P<0.001). The efficacy of the regimen of efavirenz plus indinavir was similar (53 percent) to that of the regimen of indinavir, zidovudine, and lamivudine. CD4 cell counts increased significantly with all combinations (range of increases, 180 to 201 cells per cubic millimeter). More patients discontinued treatment because of adverse events in the group given indinavir and two nucleoside reverse-transcriptase inhibitors than in the group given efavirenz and two nucleoside reverse-transcriptase inhibitors (43 percent vs. 27 percent, P=0.005).

CONCLUSIONS

As antiretroviral therapy in HIV-1-infected adults, the combination of efavirenz, zidovudine, and lamivudine has greater antiviral activity and is better tolerated than the combination of indinavir, zidovudine, and lamivudine.

[Contribution of clinical epidemiology to the management of HIV infections]

INTRODUCTION

The objective of this publication is to make clinicians more aware of clinical epidemiology through our experience in the field of human immunodefiency virus (HIV) infection.

CURRENT KNOWLEDGE AND KEY POINTS

Clinical epidemiology is aimed at studying diagnostic, therapeutic and prognostic aspects of diseases, and their consequences, with the objective of improving both scientific knowledge and patient's management. Examples, including longitudinal studies and clinical trials, illustrate the value of clinical epidemiology.

FUTURE PROSPECTS AND PROJECTS

Beyond HIV infection, the importance of both multidisciplinary collaboration and education of clinicians in regard to biostatistical and epidemiological methods is emphasized.