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Results for “Effect Modifier, Epidemiologic”

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PubMed1995

Hawthorne effect: implications for prehospital research.

STUDY OBJECTIVE: The phenomenon of altered behavior or performance resulting from awareness of being a part of an experimental study has been termed the "Hawthorne effect." Prehospital studies generally involve paramedics or are designed to use data collected by paramedics. Our objective was to determine whether paramedic performance, as measured by frequency of documentation, can be modified by (1) written notification of the importance of documentation, (2) written notification of a research project involving paramedic documentation, or (3) written notification of a quality-improvement audit of paramedic documentation. DESIGN: Prospective, sequential intervention study with five study phases. SETTING: Urban, all-advanced life support public utility model emergency medical services system with 55,000 emergency calls per year. PARTICIPANTS: One hundred forty-five paramedics who completed all ambulance run reports from August 1992 to May 1993. RESULTS: A total of 30,828 run reports was entered into the study. Baseline undocumented parameters ranged from 3.7% to 6.5%. Compared with baseline, a memo to heighten awareness (phase 2) did not alter documentation (P > or = .08). A medication study memo (phase 3) improved medication documentation (P = .0005) and allergies documentation (P = .037). A quality-improvement audit memo (phase 4) improved documentation of all parameters (P < or = .001). CONCLUSION: The Hawthorne effect occurs in prehospital research. It does not require direct observation, nor does it require direct feedback. However, it may require a perceived demand for performance. The Hawthorne effect must be considered in the design of prehospital studies and interpretation of data collected by paramedics.

Data Collection↗
PubMed1995

Defibrillation by basic emergency medical technicians: effect on survival.

Several studies have examined the effect of early defibrillation by basic EMTs on patient survival. Although the studies have a common theme of early basic EMT defibrillation, they are diverse in locations, devices, control groups, caregivers, and protocols. They provide a confusing array of information that is difficult to review, synthesize, and interpret. Metaanalysis allows data pooling of these primary studies to combine results and statistically compare the observed variation in study outcomes. The purpose of this metaanalysis was to examine the published studies of early basic EMT defibrillation to learn whether this treatment has an effect on survival of out-of-hospital cardiac arrest. Analysis of the 10 studies that met inclusion criteria showed that despite variations in design, the overall effect size for all the studies was .092, indicating a 9.2% increase in survival over what would have been expected had the EMT-Ds not intervened.

Effect Modifier, Epidemiologic↗
PubMed1999

The role of ipratropium bromide in the emergency management of acute asthma exacerbation: a metaanalysis of randomized clinical trials.

STUDY OBJECTIVE: This study was conducted to determine whether the addition of inhaled ipratropium to inhaled beta-agonist therapy is effective in the treatment of adults with acute asthma exacerbation. METHODS: Published reports of randomized, controlled trials assessing the use of ipratropium and beta-agonists in asthma were identified by a search of the MEDLINE, EMBASE, CINAHL, Biological Abstracts on CD, the Cochrane Library, and Current Contents databases. Bibliographies from identified studies and from review articles were manually searched. Published and unpublished reports in English, French, and Italian were identified and assessed for inclusion in the metaanalysis. Randomized, double-blind, placebo-controlled trials were selected in which ipratropium was used as adjunctive therapy to beta-agonists in adult patients with acute asthma exacerbation presenting to a hospital emergency department or similar acute care setting. Data were extracted independently by 2 reviewers. For eligible trials, the mean percent change in peak expiratory flow rate (PEFR), or forced expiratory volume in one second (FEV1), and their SDs were assessed in the ipratropium-treated and control groups. The effect of ipratropium on hospitalization rates and adverse effects were also analyzed. RESULTS: Data from 10 studies, reporting on a total of 1,377 patients with asthma, were pooled using a weighted average method. Compared with placebo, the use of ipratropium was associated with a pooled 7.3% improvement in FEV1 (95% confidence interval [CI] 3.8% to 10.9%), corresponding to an absolute improvement in FEV1 in the ipratropium/ beta-agonist group, which was 100 mL (95% CI 50 to 149 mL) above that seen for the group that received beta-agonist without ipratropium. Similarly, the pooled estimate of treatment effect in trials that reported data as PEFR was 22.1% (95% CI 11.0% to 33.2%), corresponding to an absolute peak expiratory flow improvement of 32 L/min (95% CI 16 to 47 L/min) in favor of the ipratropium/ beta-agonist combination group. When these data were combined using effect size as a common measure, the use of ipratropium was associated with a summary effect size of.38 (95% CI.27 to.48). Effect sizes were negatively correlated with baseline mean expiratory flows, suggesting that studies enrolling patients with more severe airflow obstruction showed greater absolute benefits of combination bronchodilator therapy. For the 3 trials reporting hospital admission data (n=1,031), patients receiving ipratropium had a relative risk of hospitalization of .73 (95% CI.53 to .99). The use of ipratropium was not associated with any severe adverse effects when used in conjunction with beta2 -agonists. CONCLUSION: There is a modest statistical improvement in airflow obstruction when ipratropium is used as an adjunctive treatment to beta2 -agonists for the treatment of acute asthma exacerbation. Although the clinical significance of this improvement in airflow obstruction remains unclear, it would seem reasonable to recommend the use of combination ipratropium/ beta-agonist therapy in acute adult asthmatic exacerbations, since the addition of ipratropium seemed to provide physiologic evidence of benefit without risk of adverse effects.

Acute Disease↗
PubMed2002

Randomized, placebo-controlled, parallel group versus crossover study designs for the study of dementia in Parkinson's disease.

In studies of dementia, crossover designs are controversial, reflecting concerns about temporal stability of disease, confounding of treatment effects with period by treatment interactions and/or carryover effects. Carryover effects are differences in the lingering effect of treatments (placebo) into subsequent periods. In the context of a trial to study the effect of donepezil on dementia in patients with Parkinson's disease, we examine two-sequence crossover studies with two or four periods, and a four-sequence design with two periods. We quantify bias in estimated treatment effects due to carryover effects and explore the use of biased estimators in hypothesis testing. For hypothesis testing, type I error rates are valid if (1) repeated administration of treatment alters the outcome only for effective treatments and (2) carryover effects due to placebo following treatment periods are nonzero only for effective treatments. For crossover and parallel group designs, sample sizes are adjusted for reduced statistical power due to carryover effects and temporal changes in variance. For the proposed clinical study, we estimate that a single-period parallel group design with baselines would require 104 patients and take about 23 months to complete. A two-sequence, four-period parallel group design with baselines would require about 80 patients and about 20 months to complete. We conservatively assume a carryover effect of 50% of the treatment effect for a two-sequence four-period crossover design. The estimated treatment effect for this model may underestimate the true treatment effect by up to 13%. The sample size/study length requirements are 28 patients or 12.4 months, respectively, a substantial saving over either parallel group design. The cost of allowing for carryover in the sample size calculation is about 1.2 months of study time.

Bias↗
PubMed2000

Selection of quality-of-life measures for a prevention trial: a psychometric analysis.

Quality-of-life (QoL) outcomes have become increasingly important in the evaluation of health interventions. The objective of the present study was to determine which of three generic QoL instruments was most suitable for use in an 8-year nutritional primary prevention trial. We compared the Duke Health Profile, the Nottingham Health Profile, and the Short Form Health Survey Questionnaire (SF36). We conducted the comparison in two stages: (1) a statistical analysis of data from a pilot study (n = 963) comparing the psychometric properties of the three instruments; and (2) an assessment of the practicality of the tools. With regard to psychometric properties, convergent validity was comparable for the three scales, and the correlation with Global Health Assessment ranged from 0.24 to 0.72. Discriminant validity was best for the SF36, with a difference between scores in healthy subjects and those with chronic disease in the range of 4.4 to 15.8 (scores could range from 0 to 100, where 100 indicates perfect health). Reproducibility was good for all three instruments, with a test-retest intraclass correlation coefficient of over 0.60 for most dimensions. DHP and SF36 performed best in terms of responsiveness. We judged the practicality of the three tools as satisfactory. We chose the SF36 for its high responsiveness. We also selected the Duke Health Profile for its practicality and favorable psychometric properties.

Cardiovascular Diseases↗
PubMed2003

Principles and issues in radiological ecological risk assessment.

This paper provides a bridge between the fields of ecological risk assessment (ERA) and radioecology by presenting key biota dose assessment issues identified in the US Department of Energy's Graded Approach for Evaluating Radiation Doses to Aquatic and Terrestrial Biota in a manner consistent with the US Environmental Protection Agency's framework for ERA. Current radiological ERA methods and data are intended for use in protecting natural populations of biota, rather than individual members of a population. Potentially susceptible receptors include vertebrates and terrestrial plants. One must ensure that all media, radionuclides (including short-lived radioactive decay products), types of radiations (i.e., alpha particles, electrons, and photons), and pathways (i.e., internal and external contamination) are combined in each exposure scenario. The relative biological effectiveness of alpha particles with respect to deterministic effects must also be considered. Expected safe levels of exposure are available for the protection of natural populations of aquatic biota (10 mGy d(-1)) and terrestrial plants (10 mGy d(-1)) and animals (1 mGy d(-1)) and are appropriate for use in all radiological ERA tiers, provided that appropriate exposure assumptions are used. Caution must be exercised (and a thorough justification provided) if more restrictive limits are selected, to ensure that the supporting data are of high quality, reproducible, and clearly relevant to the protection of natural populations.

Animals↗
PubMed2003

An investigation into expectation-led interviewer effects in health surveys.

Many large-scale health surveys use interviewers to obtain standardised information about the health of the general population. To improve response rates and data quality, the researchers/designers usually brief the interviewers to familiarise them with the survey procedures and stimulate their interest in the survey. However, it is possible that interviewers, having been exposed to researchers' expectations, may inadvertently influence respondents to produce outcomes consistent with those expectations. Such expectations are referred to here as 'expectation-led interviewer effects'. In this paper, the design and results from an experiment to test for expectation-led interviewer effects are described. The experiment involved conducting two health surveys, called the 'experimental' and the 'control', which were identical in every way except that researchers made a reference to a supposed link between childhood and adult health at the experimental survey briefing. The testing procedure was designed prior to data collection to preclude accusations of data dredging and to ensure that the type I error probability was less than 5 percent. No consistent evidence of expectation-led interviewer effects was found, bar a statistically significant effect for health questions requiring the recall of detailed quantitative information. This effect was small, however.

Adult↗
PubMed2001

Multiwave analysis of retest artifact in the National Longitudinal Survey of Youth drug use.

We examined follow-up data from surveys in 1988, 1992 and 1994 in order to estimate the prevalence and explore the correlates of retest artifact (denial) of drug use among National Longitudinal Survey of Youth respondents who disclosed lifetime cocaine or marijuana use in 1984. In the cocaine use cohort, 42% denied lifetime cocaine use during at least one follow-up wave. In the marijuana use cohort, about 29% denied lifetime marijuana use during at least one follow-up wave. Denial either leveled off (cocaine) or diminished (marijuana) between the second and third follow-up interviews. The most consistent predictors of denial in both longitudinal and cross-sectional models and across substances were race/ethnicity (black informants had increased rates of denial) and marital status (married respondents had increased rates of denial). Other predictors of denial included interviewer characteristics (social attribution), interview mode, and drug salience. The findings with respect to marijuana reporting trends parallel increased willingness of public officials to retrospectively disclose this behavior in the popular press.

Adolescent↗
PubMed2003

Effects of psychosocial interventions on quality of life in adult cancer patients: meta analysis of 37 published controlled outcome studies.

The present meta analysis summarized the results of 37 published, controlled studies that investigated the effectiveness of psychosocial interventions on quality of life (QoL) in adult cancer patients. The overall effect size of psychosocial interventions and the effect of potential moderating variables such as type and duration of intervention, sociodemographic and clinical parameters, characteristics of QoL measurement, and methodological quality of the selected studies were calculated using a meta analysis model suggested by Hunter and Schmidt. The overall effect size was 0.31 (correlation equivalent delta) which corresponds to a standardized mean difference of d=0.65 (N=3120 cancer patients). The most important moderating variable was duration of psychosocial intervention with durations of more than 12 weeks being significantly more effective than interventions of shorter duration. The meta analytical findings support the usefulness of psychosocial interventions for improving QoL in adult cancer patients.

Adaptation, Psychological↗
PubMed1999

Complementary therapies: evaluating their effectiveness in cancer.

The use of complementary therapies is common among cancer patients. However, a major concern is that very few of these therapies have been appropriately evaluated and, thus, little is known about their safety and efficacy. The gold standard for evaluating cancer treatments is the randomized controlled trial (RCT). However, there are several issues inherent to the nature and practice of complementary therapies that interfere with the straightforward use of RCTs. Alternative approaches are often highly individualized and attempt to respond to patients' needs. They are often holistic, taking into account many facets of a patient's life. Placebo effects and the role of the provider are frequently recognized as an important part of treatment. Outcomes of complementary therapies are often subjective, rather than being more objective outcomes, such as increased survival time. Although it is important to evaluate complementary therapies, it is mandatory that studies be sensitive to these issues and that existing research methods be adjusted and modified for this purpose.

Complementary Therapies↗
PubMed2000

Promoting mammography: results of a randomized trial of telephone counseling and a medical practice intervention.

BACKGROUND: Despite widespread promotion of mammography screening, a distinct minority of women have remained underusers of this effective preventive measure. We sought to measure the effects of barrier-specific telephone counseling (BSTC) and a physician-based educational intervention (MD-ED) on mammography utilization among underusers of mammography screening. DESIGN: This was a randomized controlled trial. Women meeting criteria for mammography underuse at baseline (grouped by practice affiliation) were randomized to a reminder control condition (RC group received annual mailed reminders), BSTC or MD-ED interventions and followed for 3 years. Underuse was defined by failure to get two annual or biannual mammograms over a 2- to 4-year period prior to a baseline survey. PARTICIPANTS AND SETTING: The study included 1655 female underusers of mammography aged 50-80 years who were members of two health maintenance organizations (HMO) in central Massachusetts. INTERVENTIONS: BSTC consisted of periodic brief, scripted calls from trained counselors to women who had not had a mammogram in the preceding 15 months. Women could receive up to three annual calls during the study. MD-ED consisted of physician and office staff trainings aimed at improving counseling skills and office reminder systems. MAIN OUTCOME MEASURE: Self-report of mammography use during the study period was the main outcome measure. Regular use was defined as > or =1 mammogram every 24 months. RESULTS: Forty-four percent in each intervention group became regular users compared to 42% in the RC group. Among subjects who had prior but not recent mammograms at baseline, BSTC was effective (OR=1.48; 95% CI=1.04; 2. 10), and MD-ED marginally effective (OR=1.28; 95% CI=0.88, 1.85). Most recent users at baseline and few never users became regular users (61% and 17%, respectively) regardless of intervention status. CONCLUSIONS: Among mammography underusers BSTC modestly increases utilization for former users at a reasonable cost ($726 per additional regular user).

Aged↗
PubMedDate not supplied

The use of the rapid exchange grip test in detecting sincerity of effort, Part I: administration of the test.

A review of studies that utilize the rapid exchange grip (REG) test revealed that there is no standardized test protocol for administering the test. The purpose of this study was to investigate three factors that affect the result of the REG test: the hand switch rate, the number of grips performed during the test, and the comparative tests used in the interpretation of the REG test. The 146 uninjured subjects performed a series of randomized grip strength tests including the REG test, the maximal static grip test (MSGT), and the five-rung (5R) test while making maximal and submaximal efforts. Results revealed no significant differences in peak REG scores between hand switch rates of 45 and 60 rpm. Significant differences were found for peak REG scores obtained from three vs. five trials. Peak scores from the 5R test vs. the MSGT differed significantly for maximal efforts but not for submaximal efforts. These results led to the following recommendations for a standardized protocol for administering the REG test: 1) the REG maneuver may be administered at a rate of either 45 or 60 rpm; 2) at least five hand-grip exchanges must be performed; and 3) only one comparative test, either the MSGT or the 5R test, should be used consistently for comparison with the REG maneuver. The findings of the present study, however, did not verify which static grip test should be used for comparison with REG scores.

Adolescent↗
PubMed1997

Fitting a routine health-care activity into a randomized trial: an experiment possible without informed consent?

Due to possible methodological and practical problems, many researchers refrain from using a randomized controlled trial design to evaluate procedures already embedded in routine health care. We performed a randomized controlled trial on the effects of routine individual feedback on test ordering behavior of family physicians. The trial started after 4 years of feedback and lasted for 2.5 years. With some adaptations a randomized trial proved to be possible. In evaluating health-care procedures that cannot be blinded in a traditional way, asking full and study-specific informed consent may conflict with the validity of the design. In such studies, an alternative procedure is to be considered. Our trial, with doctors as study subjects, was held on an already accepted routine procedure (feedback). This made it possible to refrain from obtaining study-specific informed consent. Consequently, a Hawthorne effect and contamination of the trial arms through information leakage could be avoided. Justification and general criteria for not obtaining full and study-specific informed consent are worked out. In health-care research on the performance of doctors or on interventions into the quality of care, obtaining a general informed consent in advance is an acceptable alternative approach.

Diagnostic Tests, Routine↗
PubMed1997

Use of goal attainment scaling in measuring clinically important change in cognitive rehabilitation patients.

Measuring the effectiveness of cognitive rehabilitation programs poses both conceptual and practical challenges. We compared several standardized outcome measures with goal attainment scaling (GAS) to assess their sensitivity to changes in health status in patients undergoing cognitive rehabilitation. GAS is a measurement approach that accommodates multiple individual patient goals, and has a scoring system which allows for comparisons between patients. Forty-four patients were evaluated. GAS yielded a mean 4.4 goals per patient. The mean gain in the GAS score was compared with the change in the Rappaport Disability Rating Scale, the Kohlman Evaluation of Daily Living Skills, the Milwaukee Evaluation of Daily Living, the Klein-Bell elimination scale and mobility scale, the Instrumental Activities of Daily Living Scale, and the Spitzer Quality of Life Index. Using a relative efficiency statistic, GAS proved more responsive than any other measure. The effect size statistic also demonstrated greater responsiveness to change with GAS compared with standard measures. GAS shows promise as a responsive measure in cognitive rehabilitation. This study replicates a similar study of GAS in frail elderly patients, suggesting that individualized measures may have broad merit in evaluating rehabilitation programs.

Activities of Daily Living↗
PubMed1997

Assessing the responsiveness of a functional status measure: the Sickness Impact Profile versus the SIP68.

In this study, the Sickness Impact Profile (SIP) and the SIP68 are studied for their ability to detect changes in health-related behavioral status. Methodological approaches toward responsiveness are invented and discussed. Next, literature findings on the responsiveness of the SIP are presented and judged for their validity. The SIP appeared to be able to demonstrate changes in the expected direction and in accordance with changes detected by other instruments. Using data from seven different longitudinal projects in populations with different diagnoses, the responsiveness of both the SIP136 and the SIP68 are subsequently studied and compared. In all populations, changes in functional status were indicated by both instruments. In terms of effect sizes, the SIP136 and the SIP68 do not differ significantly in their responsiveness. Moreover, changes detected by both SIPs appear to be valid representations of changes in health-related functional status.

Activities of Daily Living↗
PubMed1997

Interaction fallacy.

We define interaction fallacy as the situation in which heterogeneity of odds ratios suggests an interaction that does actually not exist among the corresponding risk ratios. We provide a hypothetical example of interaction fallacy between the presence of the germ-line BRCA1 mutation, age at first live birth, and breast cancer risk based on data from the literature. More generally, we present a set of hypothetical conditions under which interaction fallacy may occur.

Adult↗
PubMed1998

Testing the measurement properties of the Short Form-36 Health Survey in a frail elderly population.

The Short Form-36 Health Survey (SF-36) is a widely used measure of health-related quality of life, however, its suitability for frail older persons is not well documented. This study examines the measurement properties of the SF-36 in a frail older patient population. Patients consecutively admitted to two geriatric services (n = 146) were administered the SF-36 and comparative measures on admission and discharge. Internal consistency (0.75-0.91) and test-retest reliability (0.24-0.80) did not meet standards for clinical application of the tool. Four subscales were moderately correlated with comparative measures (Physical Function 0.53 to -0.76; Bodily Pain -0.61; Vitality -0.58; Mental Health -0.63). The results of effect size, standardized response mean, and relative efficiency statistics were consistent in documenting only minimal change for the SF-36 subscales. The SF-36 appears to be reliable and valid, although its ability to monitor clinical change for frail older patients is questionable.

Activities of Daily Living↗