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Results for “Effect Modifier, Epidemiologic”

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PubMedDate not supplied

Comparison of visual inspection and statistical analysis of single-subject data in rehabilitation research.

Single-subject designs are being advocated to conduct outcome research in rehabilitation environments. The methods provide an alternative to traditional designs based on statistical comparisons across groups. Data analysis in single subject research does not rely on statistical hypothesis testing of responses collected from a sample of subjects. Instead, visual inspection of patient responses graphed over time is the usual method of data analysis in single-subject research. This study examined the agreement between visual analysis and statistical tests of single-subject data for 42 hypothetical single-subject graphs. Specially constructed graphs allowed the systematic manipulation of different treatment effect sizes across a commonly used single-subject design. Thirty-two rehabilitation and health care providers rated each of the 42 graphs to determine whether a clinically significant treatment effect existed across the phases of the designs. Data analysis focused on two questions: (1) How much agreement was there between visual judgments and the results of statistical tests? and (2) What level of treatment effect was required to produce a finding of visual versus statistical significance? The agreement between visual analysis and statistical significance was high (86%). The sensitivity of visual inferences compared with statistical test results was 0.84, specificity was 0.88, and positive predictive value was 0.91. Both visual and statistical procedures were sensitive to medium and large treatment effects in the 42 single-subject graphs examined in this study.

Audiovisual Aids↗
PubMedDate not supplied

Case studies, single-subject research, and N of 1 randomized trials: comparisons and contrasts.

Case studies, single-subject research designs, and N of 1 randomized clinical trials are methods of scientific inquiry applied to an individual or small group of individuals. A case study is a form of descriptive research that seeks to identify explanatory patterns for phenomena and generates hypotheses for future research. Single-subject research designs provide a quasi-experimental approach to investigating causal relationships between independent and dependent variables. They are characterized by repeated measures of an observable and clinically relevant target behavior throughout at least one pretreatment (baseline) and intervention phase. The N of 1 clinical trial is similar to the single-subject research design through its use of repeated measures over time but also borrows principles from the conduct of large, randomized controlled trials. Typically, the N of 1 trial compares a therapeutic procedure with placebo or compares two treatments by administering the two conditions in a predetermined random order. Neither the subject nor the clinician is aware of the treatment condition in any given period of time. All three approaches are relatively easy to integrate into clinical practice and are useful for documenting individualized outcomes and providing evidence in support of rehabilitation interventions.

Bias↗
PubMed2001

Multimodal treatment of ADHD in the MTA: an alternative outcome analysis.

OBJECTIVE: To conduct a post hoc investigation of the utility of a single composite measure of treatment outcome for the NIMH Collaborative Multisite Multimodal Treatment Study of Children With Attention-Deficit/Hyperactivity Disorder (MTA) at 14 months postbaseline. BACKGROUND: Examination of multiple measures one at a time in the main MTA intent-to-treat outcome analyses failed to detect a statistically significant advantage of combined treatment (Comb) over medication management (MedMgt). A measure that increases power and precision using a single outcome score may be a useful alternative to multiple outcome measures. METHOD: Factor analysis of baseline scores yielded two "source factors" (parent and teacher) and one "instrument factor" (parent-child interactions). A composite score was created from the average of standardized parent and teacher measures. RESULTS: The composite was internally consistent (alpha = .83), reliable (test-retest over 3 months = 0.86), and correlated 0.61 with clinician global judgments. In an intent-to-treat analysis, Comb was statistically significantly better than all other treatments, with effect sizes ranging from small (0.28) versus MedMgt, to moderately large (0.70) versus a community comparison group. CONCLUSIONS: A composite of ADHD variables may be an important tool in future treatment trials with ADHD and may avoid some of the statistical limitations of multiple measures.

Analysis of Variance↗
PubMedDate not supplied

Effectiveness of Tai Chi exercise in improving aerobic capacity: a meta-analysis.

PURPOSE: Meta-analysis involves the integration of several studies with small sample sizes, enabling the investigator to summarize research results into useful clinical information. Tai Chi exercise has recently gained the attention of Western researchers as a potential form of aerobic exercise. A goal of this meta-analysis was to estimate the effect of Tai Chi exercise on aerobic capacity. METHODS: A computerized search of 7 databases was done using key words and all languages. Sixteen study elements were critically appraised to determine study quality. D-STAT software was used to calculate the standardized mean differences (ESsm) and the 95% confidence intervals (CI), using means and standard deviations (SD) reported on aerobic capacity expressed as peak oxygen uptake (VO2peak) (mL x kg(-1) x min(-1)). RESULTS: Of 441 citations obtained, only 7 focused on aerobic capacity in response to Tai Chi exercise (4 experimental and 3 cross-sectional). Older adults including those with heart disease participated (n = 344 subjects); on average men were aged 55.7 years (SD = 12.7) and women 60.7 years (SD = 6.2). Study quality scores ranged from 22 to 28 (mean = 25.1, SD = 2.0). Average effect size for the cross-sectional studies was large and statistically significant (ESsm = 1.01; CI = +0.37, +1.66), while in the experimental studies the average effect size was small and not significant (ESsm = 0.33; CI = -0.41, +1.07). Effect sizes of aerobic capacity in women (ESsm = 0.83; CI = -0.43, +2.09) were greater than those for men (ESsm = 0.65; CI = -0.04, +1.34), though not statistically significant. Aerobic capacity was higher in subjects performing classical Yang style (108 postures) Tai Chi (ESsm = 1.10; CI = +0.82, +1.38), a 52-week Tai Chi exercise intervention (ESsm = 0.94; C = +0.06, +1.81), compared with sedentary subjects (ESsm = 0.80; CI = +0.19, +1.41). CONCLUSIONS: This meta-analysis suggests that Tai Chi may be an additional form of aerobic exercise. The greatest benefit was seen from the classical Yang style of Tai Chi exercise when performed for 1-year by sedentary adults with an initial low level of physical activity habits. Recommendations for future research are provided and the effect sizes generated provide information needed for sample size calculations. Randomized clinical trials in diverse populations, including those with chronic diseases, would expand the current knowledge about the effect of Tai Chi on aerobic capacity.

Confidence Intervals↗
PubMed2002

Registered nurse unions and patient outcomes.

Although research shows substantial relationships between several organizational characteristics in hospitals and patient outcomes, the relationship between nurse unions and patient outcomes has not been explored. Because of the workplace chaos of the last half of the 1990s, some nurses are rethinking their relationships with unions; some have the perception that union activity has increased. It is not always clear whether changes in healthcare are associated with patient outcomes, but it is clear that hospitals/health systems with unions often engage in spirited rhetoric about what is best for patients with little objective evidence to support either view. This study examines the relationship between the presence of a bargaining unit for registered nurses and the acute myocardial infarction mortality rate for acute care hospitals in California. The authors also discuss how registered nurse wage, hospital bed size, volume of patients, and other organizational factors may influence and confound this relationship.

Acute Disease↗
PubMed1999

Systematic review of trauma system effectiveness based on registry comparisons.

BACKGROUND: Trauma registries offer distinct advantages and disadvantages when assessing the effectiveness of trauma systems. Detailed injury data and statistical comparisons that use TRISS methodology and the Major Trauma Outcome Study norms provide advantages over population-based or preventable death studies. However, miscodings and registry differences in injury severity coding limit the validity and generalizability of findings. The purpose of this study was to identify these strengths and weaknesses and to determine whether registry studies provide evidence of trauma system efficacy. METHODS: A systematic review of published literature assessing trauma systems effectiveness by using registry-based data. RESULTS: Eight of 11 articles reviewed provided comparable data and consistently demonstrated a 15 to 20% reduction in the risk of death comparing trauma system outcomes to Major Trauma Outcome Study norms. CONCLUSION: These studies provide evidence of the effectiveness of trauma systems. However, future studies that use trauma registries would be strengthened by including both prehospital and postdischarge trauma deaths, standardizing trauma registry inclusion criteria and developing a contemporary national reference norm for trauma outcome.

Canada↗
PubMed1997

Promoting screening mammography in inner-city settings. The sustained effectiveness of computerized reminders in a randomized controlled trial.

OBJECTIVES: The authors conducted a randomized controlled trial to evaluate the sustained effectiveness of a computerized reminder system in promoting mammography during a second year of continuing intervention at three primary care practices of a Health Department and a health maintenance organization in Detroit, Michigan. METHODS: Out-of-pocket mammography cost was eliminated for all participants (limited intervention). Computer-generated reminders promoting physician referral for mammography were placed in the medical records of women due for mammography 1 month in advance of their due date (full intervention). RESULTS: Among 1,225 year 2 visitors, mammography rates were 44% for full intervention versus 28% for limited intervention at the health department (adjusted odds ratio [OR] for effect of full intervention 1.84; 95% confidence interval [CI]: 1.40-2.40) and 45% for full versus 46% for limited at the health maintenance organization (adjusted OR 1.06; 95% CI 0.80-1.42). These second year results contrasted with those observed for year 1, during which a significant effect of full intervention was demonstrated for both organizations. After controlling for patient characteristics and site, the effect sizes of full intervention were reduced significantly in the second year compared with the first year (P = 0.05). CONCLUSIONS: The effect of computerized mammography reminders can be sustained in a second year of continued intervention, but individual practice sites and organizations vary in their responsiveness to the intervention. Strategies to promote periodic and repetitive procedure use must identify and address time-varying barriers to their effectiveness.

Adult↗
PubMed1998

Effectiveness of interventions to improve patient compliance: a meta-analysis.

OBJECTIVES: This article summarizes the results of 153 studies published between 1977 and 1994 that evaluated the effectiveness of interventions to improve patient compliance with medical regimens. METHODS: The compliance interventions were classified by theoretical focus into educational, behavioral, and affective categories within which specific intervention strategies were further distinguished. The compliance indicators broadly represent five classes of compliance-related assessments: (1) health outcomes (eg, blood pressure and hospitalization), (2) direct indicators (eg, urine and blood tracers and weight change), (3) indirect indicators (eg, pill count and refill records), (4) subjective report (eg, patients' or others' reports), and (5) utilization (appointment making and keeping and use of preventive services). An effect size (ES) r, defined as Fisher's Z transformation of the Pearson correlation coefficient, representing the association between each intervention (intervention versus control) and compliance measure was calculated. Both an unweighted and weighted r were calculated because of large sample size variation, and a combined probability across studies was calculated. RESULTS: The interventions produced significant effects for all the compliance indicators (combined Z values more than 5 and less than 32), with the magnitude of effects ranging from small to large. The largest effects (unweighted) were evident for refill records and pill counts and in blood/urine and weight change studies. Although smaller in magnitude, compliance effects were evident for improved health outcomes and utilization. Chronic disease patients, including those with diabetes and hypertension, as well as cancer patients and those with mental health problems especially benefited from interventions. CONCLUSIONS: No single strategy or programmatic focus showed any clear advantage compared with another. Comprehensive interventions combining cognitive, behavioral, and affective components were more effective than single-focus interventions.

Adolescent↗
PubMed1998

Short term drug abuse treatment costs and utilization: a multi-employer analysis.

OBJECTIVES: This report investigates three aspects of drug abuse treatment costs, with special emphasis on systematic differences among employers: (1) predictors of drug abuse treatment costs; (2) differentials in drug abuse treatment costs across employers; and (3) differential impacts of patient and employer characteristics on drug abuse treatment costs. METHODS: The study used multiple regression analysis of behavioral cost functions. It decomposed cost differences into employer and variable effects using an algebraic method that accounted for differences in cost functions and in population characteristics. An insurance claims database was used from 10 large self-insured employers for a 3-year period starting January 1989. RESULTS: Marginal inpatient costs generally exceeded average costs, leading to slightly increasing costs per day as length of stay increased. Marginal outpatient costs were generally about the same as average costs, implying that outpatient drug treatment maintained constant unit costs as utilization increased. Decomposition of cost differences among employers suggested that observed differences among employers and/or their carriers (who administer the benefits for the self-insured employers) and providers appeared to be at least as important as differences among the characteristics or the utilization of the people that they cover. CONCLUSIONS: National health policies aimed at reducing costs are likely to have differing impacts on different employers. Employers with high costs relative to the characteristics of their covered population may be able to achieve significant cost savings. Employers serving populations with greater risk factors may find it difficult to cut costs further.

Adult↗
PubMed1999

Application of random effects models and other methods to the analysis of multidimensional quality of life data in an AIDS clinical trial.

BACKGROUND: Current analytic methods applied to multidimensional health-related quality of life (HRQOL) data do not borrow strength across analyses and do not produce summary estimates of effect. OBJECTIVES: To compare a random effects modelling approach for the analysis of multidimensional HRQOL data to the following: (1) separate analyses for each dimension; (2) O'Brien's global test procedure; and (3) multivariate analysis of variance (MANOVA). RESEARCH DESIGN: Randomized clinical trial comparing 3 treatments (Trimethoprim-Sulfamethoxazole [TS], Dapsone-Trimethoprim [DT], and Clindamycin-Primaquine [CP] for Pneumocystis carinii pneumonia [PCP]). SUBJECTS: Patients with PCP enrolled in AIDS Clinical Trials Group Protocol 108. MEASURES: A 33-item battery assessing 7 dimensions of HRQOL: physical functioning, pain, energy, general health perceptions, disability, pulmonary symptoms, and constitutional symptoms. RESULTS: Analyses focused on changes in score from baseline to Day 7 (n = 145). Separate analyses for each dimension suggested a trend favoring CP versus TS, but using a Bonferroni correction no differences were statistically significant. O'Brien's global procedure for a test of no-treatment effect versus superiority of one treatment yielded P = 0.07. MANOVA did not reveal significant differences among treatment groups. A random effects model using fixed treatment and dimension effects and separate random effects for each person showed a significant overall treatment effect (P = 0.02); changes in scores for CP averaged 10 points greater than for TS. CONCLUSIONS: Random-effects models provide a flexible class of models for analyzing multidimensional quality of life data and estimating treatment effects because they borrow strength across dimensions.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Power analysis: Part II.

Explore the source record for details and available documents.

Data Interpretation, Statistical↗
PubMedDate not supplied

Respiratory muscle strength in older adults.

Gender-related effects and two measures of muscularity, handgrip strength and fat-free mass (FFM), were examined to determine their relationship to respiratory muscle strength. Subjects were 101 healthy older adults. In 75 subjects, the magnitude of learning effect was examined over four weekly sessions. Maximal inspiratory pressure (PImax) was lower with increasing age in women, and maximal expiratory pressure (PEmax) was lower with increasing age in both genders. The PEmax correlated with handgrip strength and FFM in men only. Performance of PImax plateaued by the third visit in both men and women. Performance of PEmax plateaued by the third measure in women and was unchanged across four measurements for men.

Aged↗