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PubMed2001

Systematic reviews of diagnostic research. Considerations about assessment and incorporation of methodological quality.

The aim of this paper is to provide a theoretical background for performing and reading systematic reviews of diagnostic studies. We first discuss items for assessment of methodological quality in diagnostic studies and then present methods on how to incorporate these quality measures in systematic reviews. The items of internal validity determine whether the presented results of the individual studies are unbiased and can be trusted. Items of external validity determine to what extent the results are applicable outside the population in which the study was performed. The issues concern the adequacy of the study population, the performance and interpretation of the diagnostic tests and the presentation of the results. Several methods exist for incorporation of issues of methodological quality into systematic reviews, such as subgroup analyses, meta-regression analysis, and methodological scores. Publications of diagnostic studies should provide sufficient information to enable assessment of the methodological quality. Furthermore, publication of results of subgroup analyses should be promoted. Methodological criteria lists might help to improve the quality of systematic reviews of diagnostic research. With the items of methodological quality in mind the general practitioner might be better equipped to critically read and interpret diagnostic reviews.

Epidemiologic Studies↗

PubMed1999

Evaluation of a campaign to improve immunization in a rural headstart program.

This study evaluated an intervention to improve immunization rates in a high poverty, medically underserved rural area employing a pretest-posttest design. The intervention expanded immunization availability, established walk-in appointment policies, and introduced intensified parent education. Formative evaluation indicated specific messages with high salience to parents. As a result, the susceptibility and severity of childhood infectious disease, the outcome efficacy of vaccines, and methods to reduce barriers to immunization were emphasized in communications with parents. Data on DTP1-4, OPV1-3, and MMR were obtained from preschools, local health departments and private medical practices before (n = 567) and after the intervention (n = 331). Following adjustment for birth order and demographics, at post-intervention a significantly greater proportion of children received 6 of 8 vaccines on time. Effect sizes were large. For example, post MMR rates were at least 2X greater than pre rates. Time-series analysis of trend data on local newspaper coverage of child health topics suggested history was not a major threat to the internal validity of this pre-post only design. The findings indicate that comprehensive intervention, targeting improvements in the availability of pediatric care, health system policies and parent behavior, can improve immunization.

Attitude to Health↗

PubMed2002

Predicting toxicity of tall larkspur (Delphinium barbeyi): measurement of the variation in alkaloid concentration among plants and among years.

Tall larkspur (Delphinium barbeyi) is the principal mountain larkspur responsible for the majority of cattle deaths on mountain rangelands in western Colorado and central and southern Utah in the United States. Ten plants in each of two tall larkspur populations in the mountains near Ferron and Salina, Utah, were marked, and single stalks were harvested periodically through the growing season for 4 yr. Toxic alkaloid concentration [alkaloids containing the N-(methylsuccimimido)-anthranilik ester group] was determined by Fourier transform infrared (FTIR) spectroscopy. Individual larkspur plants varied in alkaloid concentrations, especially in early growth (14-38 mg/g). As the concentration declined over the growing season, variation among plants also declined. There were yearly differences in alkaloid concentration among individual plants (P < 0.01) and populations (P < 0.001), even after accounting for differences in phenological growth between years. Variables such as precipitation, temperature, days since snow melt, growing degree days (sum of mean temperature each day from snow melt), and plant height and weight were all considered in a Mallows Cp multiple regression selection procedure to predict alkaloid concentration. The mixed model procedure in SAS adjusted the regression equation for locations and years. Growing degree days was the best single predictor of alkaloid levels: In y = (3.581 - 0.00423 GDD), R2 = 0.85. Internal validation of this equation within individual years and locations from which the equation was developed, produced correlations between observed versus predicted values ranging from r = 0.73 to 0.93. External validations on nine other larkspur populations produced correlations ranging from r = 0.76 to 0.99. This predictive equation can provide a tool for ranchers and land managers to make management decisions of when to graze cattle in larkspur areas.

Alkaloids↗

PubMed2003

Physical therapy for pregnancy-related low back and pelvic pain: a systematic review.

BACKGROUND: A systematic review of prospective controlled clinical trials was performed to assess the effectiveness of physical therapy interventions for the prevention and treatment of pregnancy-related back and pelvic pain. Pregnancy-related low back and pelvic pain has an impact on daily life for many women. Prevention and treatment of back and pelvic pain is therefore an important issue for all those concerned with women's health. METHODS: All prospective controlled clinical trials retrieved by systematic searching of electronic databases, checking of reference lists and contacting of authors were examined. Two reviewers independently selected trials for inclusion and independently assessed the internal validity of the included trials. Authors were contacted to obtain missing information. RESULTS: Nine trials with a total of 1350 patients were reviewed. Except for three high-quality studies, the validity of the trials was moderate to low. Two high-quality studies showed no difference in pain intensity and functional status between the exercise groups and the control groups. In the third high-quality study significant reduction in sick leave was found in favor of water gymnastics compared with no intervention. Because the included trials were considered heterogeneous with regard to study design, population intervention and outcome, no meta-analysis was performed. CONCLUSIONS: Because of heterogeneity and the varying quality of the studies no strong evidence exists concerning the effect of physical therapy interventions on the prevention and treatment of back and pelvic pain related to pregnancy. Future studies should meet current methodological standards, and interventions to be evaluated should be based on established theoretical framework.

Female↗

PubMed2002

The Bech-Rafaelsen Melancholia Scale (MES) in clinical trials of therapies in depressive disorders: a 20-year review of its use as outcome measure.

OBJECTIVE: To evaluate the psychometric properties of the Bech-Rafaelsen Melancholia Scale (MES) by reviewing clinical trials in which it has been used as outcome measure. METHOD: The psychometric analysis included internal validity (total scores being a sufficient statistic), interobserver reliability, and external validity (responsiveness in short-term trials and relapse prevention in long-term trials). RESULTS: The results showed that the MES is a unidimensional scale, indicating that the total score is a sufficient statistic. The interobserver reliability of the MES has been found adequate both in unipolar and bipolar depression. External validity including both relapse, response and recurrence indicated that the MES has a high responsiveness and sensitivity. CONCLUSION: The MES has been found a valid and reliable scale for the measurement of changes in depressive states during short-term as well as long-term treatment.

Clinical Trials as Topic↗

PubMed1991

How "blind" are double-blind studies?

Psychopharmacological studies usually attempt to eliminate "nonspecific" influences on outcome by double-blind designs. In a randomized, double-blind comparison of alprazolam, imipramine, and placebo, the great majority of panic disorder patients (N = 59) and their physicians were able to rate accurately whether active drug or placebo had been given. Moreover, physicians could distinguish between the two types of active drugs. Inasmuch as correct rating was possible halfway through treatment, concerns about the internal validity of the double-blind strategy arise.

Adult↗

PubMed2001

Issues of measurement and mechanism in meta-analyses: comment on Westen and Morrison (2001).

The authors suggest that D. Westen and K. Morrison's (2001) meta-analysis of treatment is critically limited in the consideration of measurement and mechanisms of therapeutic change. The measures included in the analysis fail to represent a comprehensive coverage of the domains within which change is expected. Moreover, they do not measure the theoretically derived constructs currently conceived as being central to each disorder. Further, the particular meta-analytical approach taken prohibits evaluation of the treatment components responsible for change. The authors reviewed the most recent data on comorbidity as an issue of treatment efficacy and generalizability, proffer an interpretation for the difference in outcome results across the 3 diagnostic groups, and discuss internally valid methodologies for the bridging from research to clinical practice.

Anxiety Disorders↗

PubMed1985

Psychosocial approaches to smoking prevention: a review of findings.

Twenty-seven school-based studies of psychosocial approaches to smoking prevention are reviewed. Two major approaches are represented: the "social influences" approach and the broader "life/social skills" approaches. The research studies are considered in four "generations": the seminal work by Richard Evans and colleagues at the University of Houston; seven "pilot" studies of improved programs at Stanford, Minnesota, New York, and Washington, with one school or classroom per experimental condition; twelve improved "prototype" studies by these four groups and others, with two or three units randomly assigned to conditions; and six studies in which maximizing internal validity was of prime concern. Reported results were fairly consistent, with each tested program seeming to reduce smoking onset by about 50%. However, none of the pilot or prototype studies considered alone provided easily interpreted results. The major contributions were improved programs and methods. The findings from the fourth generation of studies were more easily interpreted, though only two of them were interpreted with high confidence. It seems that psychosocial approaches to smoking prevention, particularly the social influences approach--fourth generation tests of the broader life/social skills approaches have yet to be reported--are effective, but at this time we know very little about why, for whom, or under what conditions. Suggestions are provided for improved future research.

Adolescent↗

PubMed1994

Is there universal recognition of emotion from facial expression? A review of the cross-cultural studies.

Emotions are universally recognized from facial expressions--or so it has been claimed. To support that claim, research has been carried out in various modern cultures and in cultures relatively isolated from Western influence. A review of the methods used in that research raises questions of its ecological, convergent, and internal validity. Forced-choice response format, within-subject design, preselected photographs of posed facial expressions, and other features of method are each problematic. When they are altered, less supportive or nonsupportive results occur. When they are combined, these method factors may help to shape the results. Facial expressions and emotion labels are probably associated, but the association may vary with culture and is loose enough to be consistent with various alternative accounts, 8 of which are discussed.

Cross-Cultural Comparison↗

PubMed2004

Population stratification in the candidate gene study: fatal threat or red herring?

Advances in molecular genetics have provided behavioral scientists with a means of investigating the influence of genetic factors on human behavior. Unfortunately, recent candidate gene studies have produced inconsistent results, and a frequent scapegoat for the lack of replication across studies is the threat of population stratification. This review of the literature on population stratification suggests that the threat may be a red herring. Reliable findings will require improved specification and measurement of the behavioral phenotypes in question, a renewed focus on internal validity, and the specification and testing of genetic factors in the context of longitudinal multivariate models. In this respect, behavioral scientists are well suited to investigating genetic factors that influence psychological mechanisms.

Case-Control Studies↗

PubMed2004

The intervention selection bias: an underrecognized confound in intervention research.

Selection bias can be the most important threat to internal validity in intervention research, but is often insufficiently recognized and controlled. The bias is illustrated in research on parental interventions (punishment, homework assistance); medical interventions (hospitalization); and psychological interventions for suicide risk, sex offending, and juvenile delinquency. The intervention selection bias is most adequately controlled in randomized studies or strong quasi-experimental designs, although recent statistical innovations can enhance weaker designs. The most important points are to increase awareness of the intervention selection bias and to systematically evaluate plausible alternative explanations of data before making causal conclusions.

Child↗

PubMed2000

Updating to the WAIS-III and WMS-III: considerations for research and clinical practice.

The Wechsler Adult Intelligence Scale-Revised (WAIS-R) and the Wechsler Memory Scale-Revised (WMS-R) are the most commonly used intelligence and memory scales in both clinical and neuropsychology. In 1997, updated versions of these instruments (the WAIS-III and WMS-III) were published. Because of the extensive use of the WAIS-R and WMS-R in the field and the body of accumulated research, there is naturally some reluctance by clinicians and researchers to update to the new versions. It is sometimes difficult for clinicians who test individuals on repeated occasions to switch over to the new versions of the scales because of the difficulty of interpreting score discrepancy between the 2 versions. Researchers, especially those conducting longitudinal research, have a similar difficulty in changing measurement devices because of the possible threat of internal validity. This article reviews the substantive revisions of the scales and outlines those issues that users should take into consideration when updating to the new versions.

Adolescent↗

PubMed2003

A self-report typology of behavioral adjustment for young children.

A large, national U.S. sample of children rated their own behavior and emotions using the Self-Report of Personality-Child version (SRP-C) of the Behavior Assessment System for Children (C. R. Reynolds & R. W. Kamphaus, 1992). Cluster analysis was used to group 4,981 self-reports (SRP-C) of children between the ages of 8 and 11 years. Theoretical and empirical considerations were used to identify a 10-cluster solution. Internal validation procedures revealed that the 10-cluster solution was well replicated by independently classifying 2 large subsamples of participants. External validation evidence revealed that only 2 of the 10 clusters could be differentiated by parent and teacher ratings of behavior problems. Peer ratings of social status and behavior, however, proved far better than adult ratings at differentiating the clusters. These findings suggest that the realm of intraindividual adjustment is not well understood by parents and teachers of these same children.

Adaptation, Psychological↗

PubMed2000

Hispanic ethnicity and risk for combat-related posttraumatic stress disorder.

Hispanic veterans are said to exhibit higher risk of developing posttraumatic stress disorder (PTSD) than veterans of other racial/ethnic backgrounds. This prediction is based largely on findings from the National Vietnam Veterans Readjustment Study (NVVRS; R. A. Kulka et al., 1990a, 1990b). This article first summarizes the findings of the NVVRS with regard to race/ethnicity and PTSD, and then it makes a careful assessment of both the external and the internal validity of these findings. Conceptual issues are addressed and, where possible, further analyses of the NVVRS data set are conducted to identify factors that account for ethnic differences in rates of the disorder. Possible mediators of the effects of Hispanic ethnicity on vulnerability to PTSD are identified, including psychosocial factors (racial/ethnic discrimination and alienation) and sociocultural influences (stoicism and normalization of stress, alexithymia, and fatalism). Areas in which future research is needed are indicated.

Confounding Factors, Epidemiologic↗

PubMed1992

Citalopram decreases desirability, liking, and consumption of alcohol in alcohol-dependent drinkers.

In previous studies serotonin uptake inhibitors such as citalopram decreased alcohol consumption in alcoholics. The mechanism of the effect is not fully understood. This study tested the hypothesis that it is mediated by changes in desire to drink and alcohol effects. After a 1-week baseline period, subjects (13 men and three women; aged 26 to 69 years; healthy, nondepressed, alcohol-dependent drinkers [mean, 6.6 drinks per day]) were randomized in a double-blind fashion to receive 40 mg/day citalopram and placebo for 1 week each, separated by a 1-week washout period. Daily standard alcoholic drinks (13.6 gm ethanol), nonalcoholic drinks, and tobacco use were recorded; evening urine samples were taken; and interest, desire, craving, and liking for alcohol were rated. Medical status, depression, and anxiety were assessed weekly, but no other treatment or advice was given. Daily alcoholic drinks significantly decreased during citalopram treatment (mean +/- SEM = 4.6 +/- 0.6) compared with placebo (5.7 +/- 0.8; p = 0.01), and the average decrease was 17.5%. Percentage of days abstinent increased during citalopram administration (27.7% +/- 5.7%) compared with placebo (15.5% +/- 3.7%; p less than 0.01). Citalopram decreased interest, desire, craving, and liking for alcohol (all p less than 0.05). There was clear internal validation of these measures in that variations in each correlated with alcohol consumption (all r greater than 0.5, p less than 0.05). Nonalcoholic drinks, self-reports of cigarettes smoked (daily smokers), and body weight did not change significantly. In experimental bar sessions, after the citalopram and placebo periods, subjects were required to consume as many of 18 minidrinks as possible (equivalent to six standard drinks) at 5-minute intervals. Subjects rated their desire for alcohol, intoxication, and mood. Citalopram had no significant effects on the desirability of alcohol or subjective feelings of intoxication. The findings indicate that serotonin uptake inhibitors may act by decreasing the urge to drink and the reinforcing effects of alcohol. Also, a naturalistic outpatient trial is a sensitive, simple, and economic procedure for detecting these drug effects.

Adult↗

PubMed2005

Multiple diagnostic techniques identify previously vaccinated individuals with protective immunity against monkeypox.

Approximately 50% of the US population received smallpox vaccinations before routine immunization ceased in 1972 for civilians and in 1990 for military personnel. Several studies have shown long-term immunity after smallpox vaccination, but skepticism remains as to whether this will translate into full protection against the onset of orthopoxvirus-induced disease. The US monkeypox outbreak of 2003 provided the opportunity to examine this issue. Using independent and internally validated diagnostic approaches with >or=95% sensitivity and >or=90% specificity for detecting clinical monkeypox infection, we identified three previously unreported cases of monkeypox in preimmune individuals at 13, 29 and 48 years after smallpox vaccination. These individuals were unaware that they had been infected because they were spared any recognizable disease symptoms. Together, this shows that the US monkeypox outbreak was larger than previously realized and, more importantly, shows that cross-protective antiviral immunity against West African monkeypox can potentially be maintained for decades after smallpox vaccination.

Animals↗

PubMed2000

Effects of an energy and micronutrient supplement on growth and development in undernourished children in Indonesia: methods.

OBJECTIVES: To describe the methodologies of a clinical trial on the effects of an energy and micronutrient supplement on the growth and development of undernourished children. DESIGN: This trial included two cohorts of children classified as nutritionally-at-risk who were randomly assigned to three treatments (condensed milk + micronutrients (E); skimmed milk + micronutrients (M); skimmed milk (S)). Supplements were given for a period up to 12 months. SETTING: Six tea plantations in Pangalengan, West Java were the site for this study. SUBJECTS: A 12-month-old (N=53) and an 18-month-old (N=83) cohort were recruited from 24 day-care-centers (DCC). Twenty children that received the S supplement were part of the 12- and 18 month-old cohort. Criteria for case inclusion were absence of chronic disease; length-for-age < or = -1 standard deviation (s.d.) and weight-for-length between -1 and -2 s.d. of the median of the reference of the World Health Organization. VARIABLES: Social variables included assessment of health facilities, childcare, housing, income and parental education. Nutrition and growth variables included dietary intake measured over a 24 hr period every 2 months; hemoglobin and three iron indicators measured at baseline, 6 and 12 months; anthropometry measured every 2 months and skeletal maturation measured every 6 months. Cognition and behavior included the assessment of mental and motor development and the behavior of the child under natural conditions. DATA ANALYSIS: An ANOVA was the statistic most frequently used to test inter-group differences and structural equation modeling was used to test the internal validity of the conceptual model of the study.

Analysis of Variance↗

PubMed2003

Mortality attributable to cardiovascular risk factors in Spain.

OBJECTIVE: To present the current burden of mortality attributable to some of the main cardiovascular risk factors in adults in Spain. METHODS: Mortality attributable to risk factors was calculated by combining their prevalence, the relative risks for death, and the number of deaths in Spain. Prevalence of hypertension (>/=140/90 mmHg), tobacco smoking, excess weight (body mass index >/=25 kg/m(2)), and self-reported diabetes were based on representative samples of the Spanish population in the 1990s. The relative risks came from valid international studies. RESULTS: About 14 000 total deaths (25% of all deaths) were attributable to hypertension in Spain's middle-aged population. A quarter of them were cardiovascular deaths. About 56 000 deaths were attributable to tobacco use in adults >/=35 y (16% of all deaths). Two-thirds of them were deaths for: lung cancer (26.5%), chronic obstructive pulmonary disease (20.9%), coronary heart disease (12.8%), and stroke (9.2%). About 28 000 deaths (8.5% of all deaths) were attributable to excess weight in adults. Two-thirds of them were cardiovascular deaths. About 2800 cardiovascular deaths were attributable to diabetes in adults >/=35 y (6% of all cardiovascular deaths). CONCLUSIONS: Mortality attributable to the risk factors studied is a major avoidable public health problem in Spain. The results presented are only illustrative but clearly show that there is considerable scope for prevention.

Adult↗