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Biomedical subjects

Peter Peduzzi

Publications and source records attributed to Peter Peduzzi.

15 recordsLinked to original sources
PubMed2006

Improved self-confidence was a mechanism of action in two geriatric trials evaluating physical interventions.

OBJECTIVE: To evaluate the mechanisms of action in two successful geriatric clinical trials that tested multicomponent physical conditioning programs and to determine whether the pathways for overall benefit were through improvement in physical ability and/or self-confidence. STUDY DESIGN AND SETTING: PREHAB and DRIVER were conducted by the Yale Pepper Center. PREHAB participants received an individualized program that focused on the impairments present (standardly tailored design); DRIVER participants received the entire intervention (global design). PREHAB enrolled 188 community-living persons, aged 75 years or older, who were physically frail but ambulatory; DRIVER enrolled 178 drivers aged 70 years or older with physical impairments associated with poor driving performance. The primary outcome for PREHAB was a disability score and for DRIVER it was a driving score; potential mediators were measures of physical ability and self-confidence. RESULTS: In PREHAB, pathways for the intervention were established through improvement in physical ability and self-confidence. In DRIVER, there was some evidence for a pathway through improved driving self-confidence but not through physical ability; however, the intervention effect was largely unexplained. CONCLUSION: Multicomponent physical interventions may operate through psychological mechanisms, and these mechanisms should be anticipated in trial designs so that the component effects can be suitably evaluated.

Activities of Daily Living↗
PubMed2006

A brief measure of perceived understanding of informed consent in a clinical trial was validated.

BACKGROUND AND OBJECTIVE: To develop and evaluate an Informed Consent Questionnaire (ICQ) for measuring self-reported perceived understanding of informed consent in a randomized clinical trial. METHODS: The study was embedded in a Department of Veterans Affairs randomized clinical trial of Gulf War veterans' illnesses (CSP#470). The trial was initiated in May 1999 at 20 hospitals and concluded in September 2001; 1,092 participants were enrolled and followed for 12 months. The reliability and validity sample included 1,086 participants evaluated at baseline, 906 at 3 months, 929 at 6 months, and 910 at 12 months. The psychometric evaluations included tests of acceptability (based on missing data, endorsement frequencies, and floor/ceiling effects), item reduction, internal consistency, and construct validity (based on Cronbach's alpha coefficients, item-total correlations, and principal components analysis). RESULTS: The ICQ had >5% missing information on some questions at baseline, indicating poor acceptability prior to the initiation of the trial; however, the scale had good acceptability at each of the follow-up visits. Psychometric evaluation following standard item reduction techniques confirmed the reliability and validity of a four-item subscale of the ICQ (ICQ-4). CONCLUSIONS: The ICQ-4 is a simple and psychometrically sound self-report measure of perceived understanding of informed consent.

Adult↗
PubMed2006

The effectiveness of screening for prostate cancer: a nested case-control study.

BACKGROUND: Screening for prostate cancer is done commonly in clinical practice, using prostate-specific antigen (PSA) tests or digital rectal examination (DRE). Evidence is lacking, however, to confirm a survival benefit among screened patients. We evaluated the effectiveness of PSA, with or without DRE, in reducing mortality. METHODS: We conducted a multicenter nested case-control study at 10 Veterans Affairs medical centers in New England. Among 71 661 patients receiving ambulatory care between 1989 and 1990, 501 case patients were identified as men who were diagnosed as having adenocarcinoma of the prostate from 1991 through 1995 and who died sometime between 1991 and 1999. Control patients were men who were alive at the time the corresponding case patient had died, matched (1:1 ratio) for age and Veterans Affairs facility. The exposure variable (determined blind to case-control status) was whether PSA testing or DRE was performed for screening prior to the diagnosis of prostate cancer among case patients, with the same time interval for control patients. The association of screening and overall or cause-specific (prostate cancer) mortality was adjusted for race and comorbidity. RESULTS: A benefit of screening was not found in our primary analysis assessing PSA screening and all-cause mortality (adjusted odds ratio, 1.08; 95% confidence interval, 0.71-1.64; P=.72), nor in a secondary analysis of PSA and/or DRE screening and cause-specific mortality (adjusted odds ratio, 1.13; 95% confidence interval, 0.63-2.06; P=.68). CONCLUSIONS: These results do not suggest that screening with PSA or DRE is effective in reducing mortality. Recommendations for obtaining "verbal informed consent" from men regarding such screening should continue.

Adenocarcinoma↗
PubMed2006

Consumer involvement in consent document development: a multicenter cluster randomized trial to assess study participants' understanding.

BACKGROUND: Despite widespread agreement on the importance of informed consent in clinical research, uncertainty remains about the adequacy of current consent procedures and documentation. METHODS: The objective of the study was to compare an informed consent document developed by a consumer group of potential study participants to one developed by the study investigators. The study was a cluster randomized, controlled study embedded in a 'parent' randomized controlled trial of 1092 participants with Gulf War veterans' illnesses recruited in 1999-2000 at 20 US medical centers. Centers were randomized to the investigator-developed or participant-developed consent document. The primary outcome measure was an Informed Consent Questionnaire-4 (ICQ-4), a validated four-item scale measuring self-reported participant understanding scored from 0 to 1. Secondary outcomes included the Client Satisfaction Questionnaire-8 and measures of study refusal and adherence to the parent trial protocol. RESULTS: There were no significant differences between consent documents on the ICQ-4 score overall or at any of the time points. Mean (95% CI) treatment differences ranged from +0.020 (-0.015, 0.055) (better understanding) at entry to -0.021 (-0.054, 0.012) (worse understanding) at three-months for the participant versus the investigator document group. There were also no significant differences in satisfaction, adherence to the protocol, or in the proportion of patients who refused to participate in the trial. LIMITATIONS: The consumer group may not have been representative of the study participants and they did not suggest dramatic changes to the consent document. The outcome assessment questionnaire was not validated prior to the trial's initiation. CONCLUSIONS: Consumer modification of the consent document did not lead to either benefit or harm in understanding, satisfaction, or study refusal and adherence rates. This study did demonstrate, however, that embedding consent studies in a clinical trial is feasible and can address important questions about informed consent without disrupting the primary study.

Adult↗
PubMed2006

Predictors of exercise compliance in individuals with Gulf War veterans illnesses: Department of Veterans Affairs Cooperative Study 470.

Although the health benefits of exercise for individuals with Persian Gulf War veterans illnesses (GWVI) are documented, many of these individuals do not exercise regularly enough to obtain benefits. The purpose of this study was to investigate factors predicting exercise compliance among individuals with GWVI in a multicenter, randomized, clinical trial. Participants were 1,092 veterans who reported at least two of the following cardinal symptoms of GWVI: (1) fatigue, (2) musculoskeletal pain, and (3) cognitive problems. Participants received exercise alone or exercise and cognitive-behavioral therapy. The overall level of compliance was relatively low during the exercise treatment phase (46.2%) and decreased by one-half during the follow-up period (23.0%). Predictors of compliance during treatment included less pain and greater age, motivation, and body mass index. Predictors of compliance during the follow-up period included less pain and greater age. The results highlight factors that affect adoption and maintenance of physical activity in a population with GWVI.

Adult↗
PubMed2005

A case study found that a regression tree outperformed multiple linear regression in predicting the relationship between impairments and Social and Productive Activities scores.

OBJECTIVE: Many important physiologic and clinical predictors are continuous. Clinical investigators and epidemiologists' interest in these predictors lies, in part, in the risk they pose for adverse outcomes, which may be continuous as well. The relationship between continuous predictors and a continuous outcome may be complex and difficult to interpret. Therefore, methods to detect levels of a predictor variable that predict the outcome and determine the threshold for clinical intervention would provide a beneficial tool for clinical investigators and epidemiologists. STUDY DESIGN AND SETTING: We present a case study using regression tree methodology to predict Social and Productive Activities score at 3 years using five modifiable impairments. The predictive ability of regression tree methodology was compared with multiple linear regression using two independent data sets, one for development and one for validation. RESULTS: The regression tree approach and the multiple linear regression model provided similar fit (model deviances) on the development cohort. In the validation cohort, the deviance of the multiple linear regression model was 31% greater than the regression tree approach. CONCLUSION: Regression tree analysis developed a better model of impairments predicting Social and Productive Activities score that may be more easily applied in research settings than multiple linear regression alone.

Aged↗
PubMed2005

Complexity of bacterial communities in a river-floodplain system (Danube, Austria).

Natural floodplains play an essential role in the processing and decomposition of organic matter and in the self-purification ability of rivers, largely due to the activity of bacteria. Knowledge about the composition of bacterial communities and its impact on organic-matter cycling is crucial for the understanding of ecological processes in river-floodplain systems. Particle-associated and free-living bacterial assemblages from the Danube River and various floodplain pools with different hydrological characteristics were investigated using terminal restriction fragment length polymorphism analysis. The particle-associated bacterial community exhibited a higher number of operational taxonomic units (OTUs) and was more heterogeneous in time and space than the free-living community. The temporal dynamics of the community structure were generally higher in isolated floodplain pools. The community structures of the river and the various floodplain pools, as well as those of the particle-associated and free-living bacteria, differed significantly. The compositional dynamics of the planktonic bacterial communities were related to changes in the algal biomass, temperature, and concentrations of organic and inorganic nutrients. The OTU richness of the free-living community was correlated with the concentration and origin of organic matter and the concentration of inorganic nutrients, while no correlation with the OTU richness of the particle-associated assemblage was found. Our results demonstrate the importance of the river-floodplain interactions and the influence of damming and regulation on the bacterial-community composition.

Animals↗
PubMed2004

Bacteria and viruses in the water column of tropical freshwater reservoirs.

In tropical freshwater reservoirs of Sri Lanka, which are linked in an aquatic network, bacterial abundance and production as well as virus abundance, frequency of viral infection and virus production were investigated together with a set of nutrient species (Kjeldahl-N, NO3-N, total P, soluble P, PO4-P). At two characteristic seasons (wet season, dry season), samples were taken from two types of reservoirs (new upland impoundment and ancient, shallow lowland reservoir), each during 4 days at various depths of the entire water columns. Kjeldahl-N and total P were greatly elevated in the wind-mixed water body of the shallow impoundment during the dry season, whereas the deeper reservoir type exhibited no obvious seasonality. In SYBR green trade mark -stained samples, bacterial abundance showed no seasonal pattern in either reservoir type. Bacterial secondary production, however, was significantly elevated in the entire water column of the shallow impoundment under wind-mixed conditions in the dry season. Highest abundance of virus particles and elevated frequency of bacteria containing mature phages were also observed in the shallow reservoir during the dry season indicating favourable conditions for virus propagation. Data from this aquatic network show that most virus parameters, such as abundance or frequency of visibly infected cells, were positively linked to bacterial abundance and production, but also to organic nitrogen or some phosphorus species. We calculated that between 13.2% and 46.1% of the bacterial standing stocks would be subjected to virus-mediated mortality. Estimates of bacteriophage production revealed that from 10 x 10(9) up to 98 x 10(9) phages were produced per litre and day. Bacteria and viruses in the studied tropical freshwater system appear to be linked to various environmental conditions and may affect processes at the ecosystem scale.

Bacteria↗
PubMed2004

Online tool for analysis of denaturing gradient gel electrophoresis profiles.

We present an online tool (EquiBands, http://www.univie.ac.at/IECB/limno/equibands/EquiBands.html) that quantifies the matching of two bands considered to be the same in different samples, even when samples are applied to different denaturing gradient gel electrophoresis gels. With an environmental example we demonstrate the procedure for the classification of two bands of different samples with the help of EquiBands.

Electrophoresis, Polyacrylamide Gel↗
PubMed2004

The Society for Clinical Trials supports United States legislation mandating trials registration. Position paper.

The official position of the Society for Clinical Trials is to support legislation in the United States and internationally that mandates registration of all controlled clinicals trials at or before enrollment of the first participant. The major trial sponsor would be responsible for ensuring contribution of trial information. The mechanism for registering trials would be through research ethics review boards, and registration would be required for ethics approval and before trial initiation. Standardized data and a unique identification number would be available for each registered trial.

Controlled Clinical Trials as Topic↗
PubMed2003

Cognitive behavioral therapy and aerobic exercise for Gulf War veterans' illnesses: a randomized controlled trial.

CONTEXT: Gulf War veterans' illnesses (GWVI), multisymptom illnesses characterized by persistent pain, fatigue, and cognitive symptoms, have been reported by many Gulf War veterans. There are currently no effective therapies available to treat GWVI. OBJECTIVE: To compare the effectiveness of cognitive behavioral therapy (CBT), exercise, and the combination of both for improving physical functioning and reducing the symptoms of GWVI. DESIGN, SETTING, AND PATIENTS: Randomized controlled 2 x 2 factorial trial conducted from April 1999 to September 2001 among 1092 Gulf War veterans who reported at least 2 of 3 symptom types (fatigue, pain, and cognitive) for more than 6 months and at the time of screening. Treatment assignment was unmasked except for a masked assessor of study outcomes at each clinical site (18 Department of Veterans Affairs [VA] and 2 Department of Defense [DOD] medical centers). INTERVENTIONS: Veterans were randomly assigned to receive usual care (n = 271), consisting of any and all care received from inside or outside the VA or DOD health care systems; CBT plus usual care (n = 286); exercise plus usual care (n = 269); or CBT plus exercise plus usual care (n = 266). Exercise sessions were 60 minutes and CBT sessions were 60 to 90 minutes; both met weekly for 12 weeks. MAIN OUTCOME MEASURES: The primary end point was a 7-point or greater increase (improvement) on the Physical Component Summary scale of the Veterans Short Form 36-Item Health Survey at 12 months. Secondary outcomes were standardized measures of pain, fatigue, cognitive symptoms, distress, and mental health functioning. Participants were evaluated at baseline and at 3, 6, and 12 months. RESULTS: The percentage of veterans with improvement in physical function at 1 year was 11.5% for usual care, 11.7% for exercise alone, 18.4% for CBT plus exercise, and 18.5% for CBT alone. The adjusted odds ratios (OR) for improvement in exercise, CBT, and exercise plus CBT vs usual care were 1.07 (95% confidence interval [CI], 0.63-1.82), 1.72 (95% CI, 0.91-3.23), and 1.84 (95% CI, 0.95-3.55), respectively. The OR for the overall (marginal) effect of receiving CBT (n = 552) vs no CBT (n = 535) was 1.71 (95% CI, 1.15-2.53) and for exercise (n = 531) vs no exercise (n = 556) was 1.07 (95% CI, 0.76-1.50). For secondary outcomes, exercise alone or in combination with CBT significantly improved fatigue, distress, cognitive symptoms, and mental health functioning, while CBT alone significantly improved cognitive symptoms and mental health functioning. Neither treatment had a significant impact on pain. CONCLUSION: Our results suggest that CBT and/or exercise can provide modest relief for some of the symptoms of chronic multisymptom illnesses such as GWVI.

Adult↗
PubMed2002

Department of Veterans Affairs Cooperative Studies Program Clinical Trial comparing combined warfarin and aspirin with aspirin alone in survivors of acute myocardial infarction: primary results of the CHAMP study.

BACKGROUND: Both aspirin and warfarin when used alone are effective in the secondary prevention of vascular events and death after acute myocardial infarction. We tested the hypothesis that aspirin and warfarin therapy, when combined, would be more effective than aspirin monotherapy. Methods and Results- We conducted a randomized open-label study to compare the efficacy of warfarin (target international normalized ratio 1.5 to 2.5 IU) plus aspirin (81 mg daily) with the efficacy of aspirin monotherapy (162 mg daily) in reducing the total mortality in 5059 patients enrolled within 14 days of infarction and followed for a median of 2.7 years. Secondary end points included recurrent myocardial infarction, stroke, and major hemorrhage. Four hundred thirty-eight (17.3%) of 2537 patients assigned to the aspirin group and 444 (17.6%) of 2522 patients assigned to the combination group died (log-rank P=0.76). Recurrent myocardial infarction occurred in 333 patients (13.1%) taking aspirin and in 336 patients (13.3%) taking combination therapy (log-rank P=0.78). Stroke occurred in 89 patients (3.5%) taking aspirin and in 79 patients (3.1%) taking combination therapy (log-rank P=0.52). Major bleeding occurred more frequently in the combination therapy group than in the aspirin group (1.28 versus 0.72 events per 100 person years of follow-up, respectively; P<0.001). There were 14 individuals with intracranial bleeds in both the aspirin and combination therapy groups. CONCLUSIONS: In post-myocardial infarction patients, warfarin therapy (at a mean international normalized ratio of 1.8) combined with low-dose aspirin did not provide a clinical benefit beyond that achievable with aspirin monotherapy.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2002

Research on informed consent: investigator-developed versus focus group-developed consent documents, a VA cooperative study.

In the Department of Veterans Affairs Cooperative Study (VACSP) #470, A Randomized, Multicenter, Controlled Trial of Multi-Modal Therapy in Veterans with Gulf War Illnesses, a substudy was designed with the primary objective of comparing the utility of an informed consent document developed by a focus group of Gulf War veterans (focus group-developed) to an informed consent document developed by the standard process involving the study investigators (investigator-developed). In December 1998 a focus group of five Gulf War veterans convened at the coordinating center and developed a consent document during three sessions. The focus group used the investigator-developed consent document as a "starting point" and then modified it by consensus agreement. They also reviewed and modified the substudy's assessment questionnaire. Utility will be evaluated in 1092 veterans participating in the parent study, VACSP #470, by directly comparing selected patient-centered outcomes between those receiving the focus group-developed consent document versus those receiving the investigator-developed document. The primary outcomes to be evaluated over a 1-year follow-up period include measures of the informed consent process, such as patient recall, expectations about risks and benefits of participation, and understanding about the voluntariness of consent. Secondary outcomes will assess the impact of the substudy on the parent study with respect to recruitment and adherence. VACSP #470 was initiated in May 1999 in 20 sites that were randomly allocated to use either the focus group-developed or investigator-developed consent document. Sites are unaware of the type of consent document assigned. This article focuses on the rationale and design of the informed consent substudy and also discusses potential ethical issues.

Focus Groups↗
PubMed2002

Analysis of randomized controlled trials.

Although the sophistication and flexibility of the statistical technology available to the data analyst have increased, some durable, simple principles remain valid. Hypothesis-driven analyses, which were anticipated and specified in the protocol, must still be kept separate and privileged relative to the important, but risky data mining made possible by modern computers. Analyses that have a firm basis in the randomization are interpreted more easily than those that rely heavily on statistical models. Outcomes--such as quality of life, symptoms, and behaviors--that require the cooperation of subjects to be measured will come to be more and more important as trials move away from mortality as the main outcome. Inevitably, such trials will have to deal with more missing data, especially because of dropout and noncompliance. There are fundamental limits on the ability of statistical methods to compensate for such problems, so they must be considered when studies are designed. Finally, it must be emphasized that the availability of software is not a substitute for experience and statistical expertise.

Data Interpretation, Statistical↗