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PubMed2006

A prospective comparison of 3 new-generation pulse oximetry devices during ambulation after open heart surgery.

OBJECTIVE: To assess the clinical performance of 3 new-generation pulse-oximetry signal-processing software systems (Philips FAST, Masimo SET, and Nellcor N-3000) during ambulation after open-heart surgery. DESIGN: Prospective, convenience sample. SETTING: Cardiac surgical progressive care unit in a 629-bed, not-for-profit, tertiary-care teaching hospital. PATIENTS: Status post-cardiac-surgery patients (n = 36) during their first postoperative ambulation. INTERVENTIONS: None. PROTOCOL: Randomization was used for digit and hand selection, and all 3 devices were used continuously during ambulation. Data on dropouts, false alarms, and correlation with heart rate were recorded. We continuously measured arterial oxygen saturation via pulse oximetry during ambulation with all 3 devices. RESULTS: Pairwise comparisons indicated significant differences among the 3 devices for data dropout and false alarm. In repeated-measures analysis, the Nellcor N-3000 had the greatest likelihood of data dropout (odds ratio of 31.9 to Masimo and 5.6 to Philips, at the 95% confidence interval). However, the converse was true for false alarms; the Masimo had the most false alarms, with an odds ratio of 17.9 to Nellcor and 2.3 to Philips, at the 95% confidence interval. There were also significantly more dropouts with all 3 devices when readings were taken on a hand on an arm from which a radial graft had been taken (p = 0.004). For heart-rate correlation, the mean absolute difference among the 3 devices was similar: Philips = 4.3 beats/min, Masimo = 5.1 beats/min, and Nellcor = 3.0 beats/min. CONCLUSIONS: There are significant differences among the 3 devices with regard to dropout and false alarms. High numbers of dropouts are problematic because no pulse-oximetry patient information is available during dropout. However, false alarms are even more problematic, because they desensitize clinicians to alarms and call into question the accuracy of displayed data. While our data highlight the statistical differences between the studied oximeters, the clinical implications of these differences warrant further study.

Adult↗
PubMedDate not supplied

Predictors of attrition from an outpatient marijuana-dependence counseling program.

We sought to characterize attrition-related characteristics of three subgroups of adults (i.e. early dropouts, late dropouts, treatment completers) who had participated in a marijuana-dependence treatment outcome study involving two alternative forms of outpatient group counseling. Early dropouts were younger, earned less income, were more likely to rent rather than own their domiciles, were less able to pay bills, and had a higher level of psychological distress than was the case with treatment completers. Late dropouts and completers were quite similar on a number of measures (e.g., age, income, home ownership, ability to pay bills, psychological stress level, confidence in being abstinent in the future), yet the lower rates of abstinence in the late dropouts largely resembled the treatment outcomes of early dropouts. The findings suggest that attrition prevention in the early phase of counseling ought to focus on motivational ambivalence as well as assisting the client in dealing with schedule conflicts or financial impediments to continued involvement. In the later stage of counseling, attrition reduction is more likely to be accomplished through efforts to better understand and address the client's dissatisfaction with treatment components delivered at that stage.

Adolescent↗
PubMed2001

A prospective study of factors influencing adherence to a continuous neuroleptic treatment program in schizophrenia patients during 2 years.

Dropout from prophylactic neuroleptic treatment is one major reason for relapse in schizophrenia patients. There is a lack of prospective studies on factors that predict medication adherence. We investigated factors suspected to predict dropout from continuous neuroleptic treatment in a 2-year prospective study involving 122 outpatients with a DSM-III-R diagnosis of schizophrenia. Forty-two (34.4%) were classified as patient-related dropouts. No significant difference between compliant patients and dropouts was found with regard to sociodemographic variables, except that compliant patients were significantly older. Also, no differences in psychopathology were seen at the beginning of treatment, but compliant patients had a longer duration of illness. Compliant patients had higher doses of neuroleptics in the initial stabilization phase and correspondingly showed more extrapyramidal signs. Physicians rated compliant patients from the beginning as more cooperative. These patients also showed significantly higher scores in positive treatment expectations. In a stepwise regression analysis, positive illness concepts, the global assessment of functioning (GAF), and the physicians' view of patients' cooperation predicted 19 percent of the variance. We concluded that the prediction of dropouts is insufficient and remains largely an unsolved problem. Future research should focus more on context factors in the search for clinically meaningful explanations of patient dropout from treatment.

Adult↗
PubMed2006

Is the superior efficacy of new generation antipsychotics an artifact of LOCF?

It has been argued that the efficacy superiority found in meta-analyses for some of the atypical antipsychotics is an artifact of higher dropout rates due to side effects in the haloperidol group combined with last-observation-carried-forward (LOCF) analyses. We therefore reanalyzed a number of pivotal studies comparing new generation antipsychotics (NGAs) and conventional antipsychotics (CAs). A total of 5 studies (n = 1271) comparing amisulpride and 3 studies (n = 2454) comparing olanzapine with CAs were reanalyzed using original patient data. We applied 4 different models: LOCF, completer analysis, LOCF but excluding dropouts due to adverse events, and LOCF but excluding all dropouts with the exception of dropouts related to efficacy. Effect sizes expressed as standardized mean differences between NGAs and CAs based on the 4 different analysis models were compared. The overall results were not different irrespective of the model used. Single studies, however, showed higher effect sizes when LOCF instead of other models was used. Overall, it does not seem that higher dropout rates due to side effects in the haloperidol groups together with LOCF analyses consistently biased the results in favor of amisulpride and olanzapine. Because the results of the single studies, however, showed that this may occasionally be the case, future studies should look at the data from different angles applying sensitivity analyses, and they may use alternative statistics such as mixed models, which need to be developed further. Ultimately, strategies to reduce dropout rates are needed.

Amisulpride↗
PubMed1996

Why do eating disorder patients drop out?

BACKGROUND: Dropout from psychotherapy is an important problem that has received little systematic attention. Although previous research suggests that the number of patients who drop out is considerable, it is not clear why they drop out or what might be done to limit the problem. The present study attempted to examine the role of the patient-therapist relationship as well as other variables for dropout among eating disorder patients. METHODS: Eating disorder patients and their therapists were assessed on a measure of treatment expectations previously developed by the author: the former were also assessed on measures of psychiatric symptoms (Crown-Crisp Experiential Index) and eating disorder psychopathology (Eating Disorder Inventory), as well as relevant background and treatment variables. Patients were divided into those who had completed their course of treatment, and those who dropped out during assessment or treatment. RESULTS: Lack of congruence between patients' and therapists' expectations of potential treatment interventions was associated with increased risk of dropout, whereas other patient-, therapist- and treatment-specific factors were not. In particular, dropouts had significantly greater expectations of being helped by insight-related interventions than their therapists. CONCLUSIONS: Dropout among eating disorder patients appears to be related to the patient-therapist relationship. It may be important for therapists to openly discuss patient expectations of treatment from the outset, and focus on particular areas of discrepancy to limit potential dropout.

Adult↗
PubMed2002

Dropping out of mental health treatment: patterns and predictors among epidemiological survey respondents in the United States and Ontario.

OBJECTIVE: The authors interviewed individuals treated for self-described mental health problems in the preceding year to examine patterns and predictors associated with dropping out of treatment. METHOD: Subjects were drawn from respondents to community epidemiological surveys carried out in representative samples of the United States and Ontario populations. Dropouts were those who had left mental health treatment during the prior year for reasons other than symptom improvement. The surveys also assessed potential dropout correlates: sociodemographic characteristics, attitudes about mental health care, disorder type, provider type, and treatment received. RESULTS: The proportion of dropouts did not significantly differ between the United States (19.2%) and Ontario (16.9%), nor did the effects of the predictors differ significantly between the two samples. Sociodemographic characteristics associated with treatment dropout included low income, young age, and, in the United States, lacking insurance coverage for mental health treatment. Patient attitudes associated with dropout included viewing mental health treatment as relatively ineffective and embarrassment about seeing a mental health provider. Respondents who received both medication and talk therapy were less likely to drop out than those who received single-modality treatments. CONCLUSIONS: Mental health treatment dropout is a serious problem, especially among patients who have low income, are young, lack insurance, are offered only single-modality treatments, and have negative attitudes about mental health care. Cost-effective interventions targeting these groups are needed to increase the proportion of patients who complete an adequate course of treatment.

Adolescent↗
PubMed1984

Therapeutic communities: what are the retention rates?

The present research is the first in a systematic investigation of retention in therapeutic communities (TCs). Findings are reported from an interrelated set of analyses clarifying retention rates and the temporal pattern of dropout. Retention information was obtained on all admissions to a nonrandom sample of seven traditional (long-term) TCs during February 1-August 15, 1979. Results showed that: (a) Across the seven programs, the 12-month retention rates ranged from 4 to 21%. Program differences were generally nonsignificant. (b) Less than 17% of admissions were readmissions. Among these, however, the number of days before initial dropout was a significant predictor of long-term retention. (c) The temporal pattern of dropout was uniform across programs. Dropout was highest within the first 14 d and declined thereafter, indicating that practically all dropouts leave within 3 months. (d) Based upon rates adjusted for those who had left treatment ("survivor rates"), estimates indicated that the likelihood of continued retention increased significantly with longer stay in treatment. (e) The temporal pattern of dropout was remarkably stable, evident in both replicational and comparative analyses; the latter involved the entire residential drug-free modality in several data systems. The present findings establish that the temporal pattern of retention is orderly, predictable, and has utility for program management and treatment planning, although the phenomenon of retention itself remains to be explained.

Adult↗
PubMed2000

Carbamazepine for cocaine dependence.

BACKGROUND: Cocaine dependence has become a substantial public health problem, developing a significant number of medical, psychological and social problems, including the spread of infectious diseases (e.g. AIDS, hepatitis and tuberculosis), crime, violence and neonatal drug exposure. Although there is no consensus regarding how to treat cocaine dependence, effective pharmacotherapy has a potentially major role to play as part of a broader treatment milieu. The anti-convulsant carbamazepine, a tricyclic medication that is widely used to treat a variety of neurological and psychiatric disorder, has also been used for treatment of cocaine dependence, although its effectiveness has not been established. OBJECTIVES: To determine whether carbamazapine (CBZ) is effective on the treatment of cocaine dependence. SEARCH STRATEGY: Electronic searches of Cochrane Library, EMBASE, MEDLINE, PsycLIT, Biological Abstracts and LILACS; scan of reference list of relevant articles; personal communication; conference abstracts; unpublished trials from pharmaceutical industry; book chapters on treatment of cocaine dependence. SELECTION CRITERIA: The inclusion criteria for all randomised controlled trials were that they should focus on the use of carbamazepine drugs versus placebo on the treatment of cocaine dependence. Trials including patients with additional diagnosis such as opiate dependence were also eligible. DATA COLLECTION AND ANALYSIS: The reviewers extracted the data independently and Odds Ratios, weighted mean difference and number needed to treat were estimated. Qualitative assessments of the methodology of eligible studies were carried out using validated checklists. The reviewers assumed that people who died or dropped out had no improvement and tested the sensitivity of the final results to this assumption. Where possible analysis was carried out according to the "intention to treat" principles. MAIN RESULTS: 5 studies were included in the review, with 455 people randomised. No differences were found regarding positive urine sample for cocaine metabolites. Scores on Spielberg State Anxiety Inventory slightly favoured carbamazepine, but didn't reach statistical significance. Dropouts were high in both groups up to 70% in the placebo group. Less dropout occurred in the Carbamazepine group (RR 0.87 95%CI 0.71-1.06). When no retention in treatment was due to side effects no differences were found. The number of participants presenting at least one side effect, reported in Kranzler (1995), was higher in the carbamazepine group (RR 4.33 95% CI 1.45-12.91). REVIEWER'S CONCLUSIONS: There is no current evidence supporting the clinical use of CBZ in the treatment of cocaine dependence. Larger randomised investigation must be considered taking into account that these time-consuming efforts should be reserved for medications showing more relevant and promising evidence.

Anticonvulsants↗
PubMed2004

Characteristics of latino men who have sex with men on the internet who complete and drop out of an internet-based sexual behavior survey.

To identify biases and threats to validity of Internet survey data collection on HIV-related risk behaviors, we studied 1,546 Latino men who have sex with men on the Internet recruited through banner impressions on a leading national gay Internet site. The study could be completed in English or Spanish. Of those commencing, 33.6% dropped out before completing the 450-field questionnaire. None of the linguistic variables (level of use of Spanish or English) predicted dropout. However, dropouts were more likely to identify as Puerto Rican or Black, to reject the $20 compensation or offer it to a charity, to not have met men for sex on the Internet, to identify as bisexual or heterosexual, and to use Web sites or personal ads for contact and to use the Internet less at home than those who completed the study. Men in seroconcordant monogamous relationships and those who had not met a man for sex on the Internet were also more likely to drop out. These data suggest that there are no linguistic and few demographic and Internet use variables that are associated with dropout. Issues of compensation and respondent characteristics that make it likely that there will be a large number of inapplicable data fields in the questionnaire appear to be significant predictors of dropout. Although there were many data missing, the dropouts did not appear to be at greater HIV-associated risk than the completers. The fact that there appear to be few systematic demographic or Internet use biases in dropouts suggests that the completers do not represent a seriously skewed sample of those Latinos who commence the Internet survey.

Analysis of Variance↗
PubMed1999

Testing differences in response trends across a normalized time domain.

A two-stage mixed model analysis of repeated measurement calculates participant-specific regression slopes relating change in available measurements to associated assessment times, and then the difference between mean regression slopes in two or more treatment groups is tested for significance against the within-groups variability of the participant-specific regression slopes. It is not necessary that all participants have the same schedule or number of repeated measurements. However, when dropouts are included in an "intent to treat" analysis, the shortened treatment exposures for the dropouts substantially increase variability and reduce power of tests for differences in rates of change. Previous work has suggested that normalizing the time scale to unit length for all participants prior to fitting the individual regression equations materially reduces the power attenuation produced by dropouts. This article reports a more detailed evaluation of the enhanced robustness against dropouts that is achieved by rescaling the time dimension. The robust analysis is recognized to be equivalent to weighting ordinary least squares regression on the original time scale by the duration of treatment for each participant. Slope coefficients calculated across a shortened time span for dropouts are less stable, so they are given less weight in defining the (linear) treatment effects.

Bias↗
PubMed1983

Improvement in clients who have given different reasons for dropping out of treatment.

Addressed the dropout problem by (a) directly asking clients their reasons for dropping out; and (b) assessing pretherapy to follow-up symptom change in clients grouped by dropout reason. Forty-six dropouts who had been administered the Brief Symptom Inventory at intake were contacted 3 months later. At follow-up they were asked their reasons for dropping out and readministered the Brief Symptom Inventory. It was found that 39% quit due to "no need for services," 35% due to "environmental constraints," and 26% due to "dislike of services." The "no need for services" and "environmental constraints" groups had significant decreases in intake to follow-up Brief Symptom Inventory scores. Dropouts were found to be a heterogeneous group whose follow-up adjustment was related to termination reason. This contradicts prevailing notions that consider all dropouts as treatment failures.

Adjustment Disorders↗
PubMed2006

Treatment attrition during group therapy for social phobia.

Psychological group treatments, such as behavioral or cognitive-behavioral therapy, are generally effective interventions for social phobia. However, a substantial number of individuals discontinue these treatments prematurely. Participant attrition can threaten the validity of treatment outcome studies if attrition during therapy does not occur randomly. In order to examine this issue, we studied 133 individuals with a principal diagnosis of social phobia who initiated a 12-week behavioral or cognitive-behavioral group treatment for social phobia. Thirty-four participants discontinued therapy prematurely. These dropouts were compared to treatment completers in demographic characteristics, Axis I and II psychopathology, and their attitude toward treatment. The results only showed a small difference between treatment completers and dropouts in their attitude toward treatment: dropouts rated the treatment rationale as less logical than completers at the beginning of treatment. No other differences between dropouts and completers were observed. Therefore, dropouts are unlikely to present a serious threat to the external validity of treatment outcome studies for social phobia.

Adolescent↗
PubMedDate not supplied

Intent-to-treat analysis for clinical trials: use of data collected after termination of treatment protocol.

Following patients for a period of time after termination of treatment protocols is a common practice in clinical trials of drug treatments. After termination of the protocol treatment, patients are usually provided with medical care as deemed appropriate, e.g. different doses of the same drug, augmentation with other drugs, or different drugs. Data collected on patients when they are not in the treatment protocol are termed "off-treatment" data to be differentiated from "on-treatment" data that are collected while patients are in the treatment protocol. The purpose of the present paper is to describe some recent statistical methodological advances in the use of "off-treatment" data for intent-to-treat (IT) analysis using mixture models [Biometrics 52 (1996) 1002]. Two-piece spline models conditional on the protocol treatment dropout time are developed first. The two pieces of the spline model represent the on-treatment and off-treatment segments of data and are joined at the dropout time. The weighted average of the two-piece conditional models across realizations of the dropout times provides the mixture model for the pragmatic IT analysis. The weights are the estimates of the probabilities of the dropout times. The mixture model is amenable to an explanatory analysis which assumes that the patients remain on their assigned treatments. The model allows the parameters of the splines to depend on the dropout time. Statistical inference is based on bootstrap sampling procedures. We have illustrated this methodology using data from a drug trial comparing nortriptyline and paroxetine in the treatment of major depression in older patients.

Clinical Trials as Topic↗
PubMed2003

Good treatment outcomes in late-life depression with comorbid anxiety.

BACKGROUND: Late-life depression studies have found that comorbid anxiety, as a symptom or comorbid disorder, is associated with poorer treatment response and increased likelihood of dropout. This study evaluated the impact of comorbid anxiety on response, dropouts, and side effects, in elderly subjects treated for depression. METHODS: We analyzed data from a 12-week trial comparing nortriptyline and paroxetine in 116 patients aged 60 and older with depression. Subjects classified as having anxious depression were compared to those with nonanxious depression in terms of treatment response rate, time to response, dropout rate, and early side effects. The analysis was replicated with another study, in which 125 subjects aged 69 and older were treated openly with paroxetine and interpersonal psychotherapy. RESULTS: Anxious and nonanxious groups did not differ in terms of response rates, time to response, dropout rates, or time to dropout. Side effects declined more quickly and more significantly in the anxious group than in the nonanxious group. LIMITATIONS: Subjects were treated in a specialty mental health setting, and the findings may not apply in other settings. CONCLUSIONS: We found no association between comorbid anxiety and a poorer prognosis during acute treatment of late-life depression. For elderly patients with anxious depression, standardized treatment in the mental health sector is associated with a good response.

Age of Onset↗
PubMed2003

Minimizing attrition in a long-term clinical trial of pediatric asthma.

BACKGROUND: Despite increased attention focused on the need to prevent patient attrition in long-term clinical trials, high dropout rates have threatened the success of numerous studies. OBJECTIVE: To evaluate the disease, demographic, and psychological factors associated with missed visits and study dropout to help improve patient management in long-term clinical trials. METHODS: Predictors of attrition were examined within the Childhood Asthma Management Program (CAMP), a large, multicenter clinical trial that followed up 1,041 children with asthma for 4 to 6 years. RESULTS: Eighty-two percent of patients attended all study visits. The tendency to miss visits was increased among older children with milder asthma, lower intellectual and social competence, and more symptoms of behavioral problems and emotional distress. Forty-two patients who missed 3 or more visits in a row and did not attend the final visit were considered study dropouts; these patients at baseline had milder asthma; lower cognitive, academic, and social competence skills; and more family conflict and distress than found among participants who remained in the study. The 49 children who had erratic attendance but did not drop out also had lower intellectual and academic skills and less family social support. CONCLUSIONS: The 4% dropout rate in CAMP was lower than reported in any previous long-term asthma trial. The findings of milder disease, decreased psychological resources, and increased distress in problem-attendance patients can assist in identifying patients who are at risk for missed visits or dropout during the trial either to block their entry into the trial or to focus efforts at maintaining their attendance once enrolled in the trial.

Anti-Asthmatic Agents↗
PubMed2002

Joint modeling of event time and nonignorable missing longitudinal data.

Survival studies usually collect on each participant, both duration until some terminal event and repeated measures of a time-dependent covariate. Such a covariate is referred to as an internal time-dependent covariate. Usually, some subjects drop out of the study before occurrence of the terminal event of interest. One may then wish to evaluate the relationship between time to dropout and the internal covariate. The Cox model is a standard framework for that purpose. Here, we address this problem in situations where the value of the covariate at dropout is unobserved. We suggest a joint model which combines a first-order Markov model for the longitudinally measured covariate with a time-dependent Cox model for the dropout process. We consider maximum likelihood estimation in this model and show how estimation can be carried out via the EM-algorithm. We state that the suggested joint model may have applications in the context of longitudinal data with nonignorable dropout. Indeed, it can be viewed as generalizing Diggle and Kenward's model (1994) to situations where dropout may occur at any point in time and may be censored. Hence we apply both models and compare their results on a data set concerning longitudinal measurements among patients in a cancer clinical trial.

Algorithms↗
PubMed2000

Determinants of attrition from cessation treatment in smokers with a history of major depressive disorder.

Attrition from smoking cessation treatment by individuals with a history of major depression was investigated. An investigation of preinclusion attrition examined differences between eligible smokers who did (n = 258) and did not (n = 100) attend an initial assessment session. Postinclusion attrition was investigated by comparing early dropouts (n = 33), late dropouts (n = 27), and treatment completers (n = 117). Those who failed to attend the assessment session were more likely to be female, to smoke cigarettes with higher nicotine content, and to have a history of psychotropic medication use. Early-treatment dropouts reported a higher smoking rate than late-treatment dropouts and endorsed more symptoms of depression than late dropouts and treatment completers. Results are compared with previous investigations of smoking cessation attrition, and implications for treatment and attrition prevention are discussed.

Adult↗
PubMed1992

Long-term weight control study. VI. Individual participant response patterns.

We analyzed the individual response patterns of all 121 participants who entered the study. Fifty-one participants completed up to week 190. In 26 completers, the response pattern consisted of an initial beneficial effect (greater than or equal to 6 months of weight loss greater than or equal to 10% from baseline) and later success (weight loss of greater than or equal to 10% from baseline at week 160). These successful participants had lost 14.1 +/- 1.0 kg (mean +/- SEM); 15.9% +/- 0.9% of initial weight) at week 160 and 8.1 +/- 1.2 kg (9.1% +/- 1.3% of initial weight) at week 190. A second pattern observed in 16 completers consisted of initial benefit and later partial success (loss of 0.1% to 9.9% at week 160). Other response patterns observed in completers included showing initial benefit only (n = 3) and no success (n = 6). Seventy of the 121 participants left the study before week 190. There were 22 "dropout successes" who had consistent weight loss for 1 year or more and were greater than or equal to 10% below their initial weights at time of dropout. Fifteen "dropouts with initial benefit" stayed in the study for greater than or equal to 1 year with initial benefit (weight loss greater than or equal to 10% from baseline maintained for greater than or equal to 6 months). Medication-related reasons accounted for only 10 of the 37 dropouts in the group with initial or later benefit. Minimal benefit was seen in 17 dropouts. Another 16 were in the study less than 1 year. Analysis of individual participant responses made some other generalizations possible. Participants receiving continuous medication lost more weight and had fewer adverse effects than those receiving targeted intermittent medication. Upward dose adjustment appeared to help 24 participants achieve the criteria for late or partial success. Analyses of individual participant responses can suggest ways to optimize anorectic medication use for individual patients.

Adult↗