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At least 145 records · Page 8Linked to original sources
PubMed2001

Dropout rates in randomised antipsychotic drug trials.

RATIONALE: It has been assumed that new atypical drugs improve treatment compliance due to fewer adverse effects. Data supporting this assumption are scarce. OBJECTIVES: The aim of this study was to study attrition rates in randomised controlled trials of oral administration of conventional antipsychotic drugs, atypical antipsychotic drugs and placebo. METHODS: The database of the Schizophrenia Module of the Cochrane Library was utilised for the present study. The data in the Cochrane Module are collected by identifying relevant randomised controlled trials from several electronic databases and other sources. Number of dropouts was defined as patients leaving the study preterm due to any reason. RESULTS: Data from 328 treatment groups, consisting of 18,585 randomised subjects from 163 drug trials, were entered in the analysis. One-third of the subjects had dropped out of the trials. The dropout rates significantly increased for each calendar year. Year of trial publication, type of drug and trial length remained statistically significant contributors to dropout rates. In a model incorporating year of publication and trial length, placebo groups and groups treated with conventional antipsychotics had significantly higher attrition rates than groups treated with atypical drugs. When clozapine-treated groups were excluded from the analysis, no statistically significant advantage for atypical drugs over conventional drugs remained. CONCLUSIONS: Trial data implicate that a better compliance can be achieved by favouring atypical drugs rather than conventional alternatives in the treatment of schizophrenia. However, this effect is found only when groups treated with the atypical antipsychotic clozapine are included in the analysis. Our study did not find evidence for a statistically significant superiority in acceptability of novel atypical drugs when compared to conventional antipsychotics.

Antipsychotic Agents↗
PubMed2005

Missing forms and dropout in the TME quality of life substudy.

OBJECTIVE: Missing forms may pose problems in health related quality of life (QOL) studies, because the absence of a QOL measure may be related to the patient's health and hence to the patient's QOL itself. Studying patterns of missingness, dropout, and the possible impact of missing data on QOL measures is an important step in reporting outcomes of QOL studies. We study patterns of dropout and evaluate the impact of missing forms in the TME QOL substudy. METHODS: Patients with rectal cancer, randomized to receive either radiotherapy plus total mesorectal excision (TME) or TME only were included in the TME trial. QOL was evaluated in 1302 Dutch patients, before treatment, and 3, 6, 12, 18 and 24 months after surgery. Here only the visual analogue score (VAS) was studied. RESULTS: At baseline, differences between VAS scores were found with respect to whether the QOL forms were dated before or after radiotherapy and surgery. Differences were small between different statistical methods accounting for dropout; only a cross-sectional analysis gave biased results. CONCLUSION: The results of the sensitivity analysis indicated that a linear mixed model analysis is a reliable and attractive approach for this study.

Analysis of Variance↗
PubMed1992

A test for the difference between two treatments in a continuous measure of outcome when there are dropouts.

Consider a randomized clinical trial that is designed to compare two treatments in which the treatment continues during the entire period of the study. Some subjects may refuse to complete the protocol and will not return for the final evaluation. Since the reason for dropping out may be related to the subject's self-assessed evaluation of the usefulness of the treatment or to undesirable side effects of the treatment, subjects who drop out cannot be treated as a random sample of those who entered the trial. We consider the situation where the measure of efficacy of the treatment is continuous. Under the assumption that the expected value of the measure for those who drop out is not better (the direction depends on the measure) than that for those who complete the study, we propose an adjustment to the usual test for a difference between treatments that allows for the inclusion of the probable effect of the dropouts; this provides a bound on the test for efficacy of the treatment. First, we estimate a predetermined percentile, such as the median score, of the control, or placebo, group and assign this score to all those who dropped out from both groups and to all subjects in both groups with scores that are worse than the assigned score. A Mann-Whitney statistic is then used to test the equality of the distributions of the two groups. We show by simulation that this modified test is equivalent to a test using the complete data and has greater power than that obtained when including the dropouts by assigning the worst observed score to them. This test will be less sensitive to bias that is induced by exclusion of dropouts from the final evaluation.

Bias↗
PubMed2005

Reasons for dropout from drug abuse treatment: symptoms, personality, and motivation.

Previous research has identified risk factors for early attrition from substance abuse treatment, but has not assessed reasons for dropout from the client's perspective. Interview and self-report assessment data were collected from 24 clients who prematurely terminated outpatient treatment to evaluate their subjective reasons for dropping out and the association of these reasons with demographic and clinical variables. Items from scales indicating problems with client motivation or conflicts with program staff were the most commonly endorsed. The severity of participant's symptoms and logistical problems interfering with appointments were less commonly reported as reasons for dropping out. Demographic, substance abuse, and motivational stage indicators were infrequently associated with subjective reasons for dropout. In contrast, indicators of maladaptive personality functioning were strongly associated with many reasons for dropping out, especially concerns about privacy and boundary issues within the program. Results from this preliminary evaluation will guide the development of an instrument and intervention focused on dropout risk factors and treatment reengagement.

Adult↗
PubMed2004

Reasons for dropout in an in vitro fertilization/intracytoplasmic sperm injection program.

OBJECTIVE: To gain more insight into psychological aspects of dropping out from IVF-ICSI. DESIGN: Prospective cohort study. SETTING: University hospital-based tertiary care fertility clinic. PATIENT(S): Women entering their first treatment cycle of IVF or ICSI. INTERVENTION(S): Standardized psychological questionnaires were administered before the start of the treatment and after treatment. MAIN OUTCOME MEASURE(S): Reasons for dropout, state and trait anxiety, depression, and marital and sexual satisfaction. RESULT(S): Baseline psychological factors and the probability of dropout after IVF-ICSI treatment were found to be associated in the group that stopped treatment for psychological reasons. Those who were denied further treatment by the medical team, the "actively censored" group, did not show pretreatment differences regarding psychological measures in comparison with those who continued treatment. After treatment, the group that was denied further treatment showed higher levels of anxiety and depression compared with those that continued. CONCLUSION(S): Dropout, being a well-known phenomenon in IVF-ICSI, is related to preexisting psychological factors in IVF-ICSI. Actively censored patients were psychologically well-adjusted before treatment, but this changed after censoring.

Adult↗
PubMed1983

Predictors of dropout from cardiac exercise rehabilitation. Ontario Exercise-Heart Collaborative Study.

The Ontario Exercise-Heart Collaborative Study was a multicenter randomized clinical trial of high intensity exercise for the prevention of recurrent myocardial infarction in 733 men. Of the 678 subjects who could have participated for at least 3 years, 315 (46.5%) dropped out. Stepwise multiple linear logistic regression analysis was carried out to examine the relation between subject characteristics and the probability of dropping out during the study. Analysis was performed on the entry group as a whole by considering those subjects who had reinfarction while complying with the program and also by excluding all subjects with reinfarctions. The consistent and statistically significant predictors of dropout in both analyses were smoking and a blue collar occupation. Angina was significantly associated with dropout only when reinfarctions were excluded. It may be important to consider these factors when investigating the potential for compliance-improving strategies in reducing dropout from exercise rehabilitation programs.

Adult↗
PubMed1999

Prognostic factors in patients continuing in vitro fertilization or intracytoplasmic sperm injection treatment and dropouts.

OBJECTIVE: To investigate whether cumulative pregnancy rates using life table analysis but without considering dropouts are representative of the whole population of patients entering an in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) program. DESIGN: Retrospective study. SETTING: University hospital-based infertility center. PATIENT(S): One thousand one hundred sixty-nine patients entering our IVF/ICSI program from January 1993 to December 1996. INTERVENTION(S): Comparison of prognostic factors between pregnant and nonpregnant patients, and between patients continuing IVF/ICSI treatment and dropouts. MAIN OUTCOME MEASURE(S): Prognostic factors, such as patient age, cancellation of oocyte retrieval because of poor response to ovarian stimulation, number of oocytes retrieved, fertilization rate, number and quality of embryos transferred. RESULT(S): No statistical differences in prognostic factors were found between patients continuing IVF/ICSI treatment and dropouts. CONCLUSION(S): Cumulative pregnancy rates using life table analysis can be considered representative of the whole population of patients for at least the first three treatment cycles.

Adult↗
PubMed1998

School importance and dropout among pregnant adolescents.

PURPOSE: This study examined the relationship of psychological well-being, social support, and demographic variables to school importance and school dropout among pregnant teens. METHOD: Fifty-one Caucasians and 68 African-Americans (mean age = 16.7 years, mean weeks pregnant = 23) were recruited from two Baltimore area prenatal teen clinics. The adolescents completed questionnaires measuring depression, self-esteem, mastery, parental and friend support, demographic characteristics (i.e., age, marital status, ethnicity, socioeconomic status), school importance, and status. RESULTS: Most adolescents were enrolled in school or had graduated (69.7%), were receiving at least passing grades (78.7%), and perceived finishing high school as very important (76.7%). Blacks were more likely to say school was important (p < 0.001), were less likely to drop out (p < 0.01), and received higher grades (p < 0.01) than whites. Dropouts had lower family incomes than current school attenders and graduates (p < 0.05). One measure of psychological well-being (mastery, p < 0.01) was positively correlated with school importance. Social support did not correlate with school importance or dropout. CONCLUSIONS: These findings suggest that dropping out of school among pregnant teens may be more strongly related to sociocultural factors than to individual characteristics such as emotional support and psychological well-being. Overall, this study reveals a positive picture of educational continuation and performance during pregnancy, with most adolescents recognizing the importance of education and remaining in school.

Adolescent↗
PubMed1989

On dropouts and refusers in child psychotherapy: reply to Garfield.

We agree with Garfield that there is value in keeping criteria for dropout groups consistent across studies. Because our methods served this goal, we are puzzled at this part of his critique. The term dropout, as used in our study, might reasonably be replaced with Garfield's term refuser; however, the procedural realities of our child clinics make both terms appropriate. At Garfield's suggestion, we present new data on those youngsters he considers true dropouts; analyses reveal that the results we previously reported would have been the same had we used this group.

Child↗
PubMed2006

Adolescent and parent therapeutic alliances as predictors of dropout in multidimensional family therapy.

The authors examined the relations between adolescent-therapist and mother-therapist therapeutic alliances and dropout in multidimensional family therapy for adolescents who abuse drugs. The authors rated videotapes of family therapy sessions using observational methods to identify therapist-adolescent and therapist-mother alliances in the first 2 therapy sessions. Differences in adolescent and mother alliances in families that dropped out of therapy and families that completed therapy were compared. Results indicate that both adolescent and mother alliances with the therapist discriminated between dropout and completer families. Although no differences were observed between the 2 groups in Session 1, adolescents and mothers in the dropout group demonstrated statistically significantly lower alliance scores in Session 2 than adolescents and parents in the completer group. These findings are consistent with other research that has established a relationship between therapeutic alliance and treatment response.

Adolescent↗
PubMed2006

On the treatment effect in clinical trials with dropout.

Patient's dropout often occurs in clinical trials with multiple scheduled visits, which results in a great challenge in the analysis of incomplete data. As the first step, one has to define a relevant treatment effect parameter, which is not straightforward in the presence of dropout. We discuss and compare two different treatment effect parameters that are adopted in most analyses of clinical data: the study-end treatment effect and the last-observed treatment effect. Some related issues, such as the estimability of causal parameters, the dependence of study parameters on the dropout patterns, and the use of the last observation carry forward, are also discussed.

Clinical Trials as Topic↗
PubMedDate not supplied

Accounting for dropout bias using mixed-effects models.

Treatment effects are often evaluated by comparing change over time in outcome measures. However, valid analyses of longitudinal data can be problematic when subjects discontinue (dropout) prior to completing the study. This study assessed the merits of likelihood-based repeated measures analyses (MMRM) compared with fixed-effects analysis of variance where missing values were imputed using the last observation carried forward approach (LOCF) in accounting for dropout bias. Comparisons were made in simulated data and in data from a randomized clinical trial. Subject dropout was introduced in the simulated data to generate ignorable and nonignorable missingness. Estimates of treatment group differences in mean change from baseline to endpoint from MMRM were, on average, markedly closer to the true value than estimates from LOCF in every scenario simulated. Standard errors and confidence intervals from MMRM accurately reflected the uncertainty of the estimates, whereas standard errors and confidence intervals from LOCF underestimated uncertainty.

Analysis of Variance↗
PubMed2005

Effect of dropouts on sample size estimates for test on trends across repeated measurements.

Sample size calculation is an important component at the design stage of clinical trials. We investigate the implications of dropouts for the sample size estimates in testing differences in the rates of changes produced by two treatments in a randomized parallel-groups repeated measurement design. Statistical models for calculating sample sizes for repeated measurement designs often fail to take into account the impact of dropouts correctly. In this article, we examine the impact of dropouts on sample size estimate and compare the power with the approach of Jung and Ahn [Jung, S. H., Ahn, C. (2003). Sample size estimation for GEE method for comparing slopes in repeated measurements data. Stat. Med. 22: 1305-1315] with that suggested by Patel and Rowe [Patel, H., Rowe, E. (1999). Sample size for comparing linear growth curves. J. Biopharm. Stat. 9:339-350] through a simulation study.

Clinical Trials as Topic↗
PubMed2002

Cigarette smoking and perceived health in school dropouts: a comparison of Mexican American and non-Hispanic white adolescents.

OBJECTIVE: To examine the relations between educational attainment and health (cigarette smoking and perceived health) in Hispanic adolescents. METHOD: Participants included 3,360 Mexican American and non-Hispanic white adolescents ranging in age from 12 to 21 years. The sample included school dropouts, academically at-risk students, and control students. RESULTS: School dropouts were 6.46 times more likely and academically at-risk students were 2.80 times more likely to smoke heavily than were control students. In addition, school dropouts reported poorer health than did their peers. Results suggest that the relation between educational attainment and perceived health is mediated by cigarette smoking. CONCLUSIONS: Increased awareness of educational attainment as a significant risk factor for smoking in Hispanic adolescents will enable smoking cessation services to be targeted more effectively.

Adolescent↗
PubMed1991

Early dropouts from psychotherapy.

Ninety-six patients requesting psychotherapy were studied prospectively at the time of screening interview by four senior psychiatrists using a variation on Luborsky's Helping Alliance questionnaire and the Osgood Semantic Differential. Significant differences were found at the time of screening between early dropouts and continuers, among screeners' rate of early dropouts, and among patients' perceptions of screeners. The screener with a high early dropout rate was seen as being more passive and less potent, and offering less new understanding than other screeners. Patients who dropped out early experienced a less strong helping alliance, felt they gained less new understanding, liked the clinician less well, felt less well liked and less respected, and saw the interviewer as more passive and psychotherapy as less potent than did continuers.

Attitude to Health↗
PubMed1986

Academic dropout or academic success: a model for prediction.

Why do some students who qualify for admission to optometry school become academic dropouts while others succeed? This question was addressed in a study which compared the admission records of 21 academic dropouts from three classes at the University of Houston College of Optometry (UHCO) with 269 retained students. Academic dropouts were found to have significantly lower preoptometry grades, lower Optometry College Admission Test (OCAT) scores, attended less competitive (i.e., less selective) undergraduate institutions, scored lower on the California Psychological Inventory (CPI), and were older than retained students. When these differentiating admission variables, excepting age, were applied to a new entering class, prediction of subsequent academic dismissal or serious academic difficulty was highly accurate. However, it was found that such prediction must take into account not only areas of weakness, i.e., academic and psychological factors which place a student at risk, but also areas of strength which give the student an advantage. For all students, regardless of age, sex, or ethnic origin, it was the ratio of "advantage" factors to "risk" factors which gave the most valid prediction of academic success or failure.

Achievement↗
PubMed2007

Predicting school dropout and adolescent sexual behavior in offspring of depressed and nondepressed mothers.

OBJECTIVE: To examine predictors of school dropout and adolescent sexual behavior in offspring of depressed and nondepressed mothers. Possible moderators of the relation between maternal depression and these outcomes also were explored. METHOD: Participants were 240 mothers and adolescents assessed annually from 6th through 12th grade. Interviews and questionnaires measured the chronicity and severity of the mother's depressive episodes, the mother's educational attainment, socioeconomic status, the presence of a father, the adolescent's IQ, externalizing behaviors, and substance use disorders. RESULTS: Substance use disorders before ninth grade significantly predicted higher rates of both school dropout and adolescent sexual behavior. Lower levels of mother's educational attainment and higher rates of adolescent's externalizing behaviors in grades 6 through 8 predicted higher school dropout. Higher IQ was associated with a lower likelihood of dropping out among offspring of never or moderately depressed mothers, but not for offspring of chronic/severely depressed mothers. Among offspring of never or moderately depressed mothers, the presence of a male head of household was associated with lower rates of adolescent sexual behavior, but not among offspring of chronically/severely depressed mothers. CONCLUSIONS: These findings have implications for the development of programs aimed at preventing behavior problems in high-risk adolescents.

Adolescent↗
PubMed2000

Reparameterizing the pattern mixture model for sensitivity analyses under informative dropout.

Pattern mixture models are frequently used to analyze longitudinal data where missingness is induced by dropout. For measured responses, it is typical to model the complete data as a mixture of multivariate normal distributions, where mixing is done over the dropout distribution. Fully parameterized pattern mixture models are not identified by incomplete data; Little (1993, Journal of the American Statistical Association 88, 125-134) has characterized several identifying restrictions that can be used for model fitting. We propose a reparameterization of the pattern mixture model that allows investigation of sensitivity to assumptions about nonidentified parameters in both the mean and variance, allows consideration of a wide range of nonignorable missing-data mechanisms, and has intuitive appeal for eliciting plausible missing-data mechanisms. The parameterization makes clear an advantage of pattern mixture models over parametric selection models, namely that the missing-data mechanism can be varied without affecting the marginal distribution of the observed data. To illustrate the utility of the new parameterization, we analyze data from a recent clinical trial of growth hormone for maintaining muscle strength in the elderly. Dropout occurs at a high rate and is potentially informative. We undertake a detailed sensitivity analysis to understand the impact of missing-data assumptions on the inference about the effects of growth hormone on muscle strength.

Aged↗