Estimating daily urine volume in psychiatric patients: empiric confirmation.
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Adult↗
Biomedical subjects
D Hedeker
Publications and source records attributed to D Hedeker.
A longitudinal study of plasma cortisol and depressive symptomatology by random regression analysis.
The authors utilized a random regression model to test the longitudinal relationship between depressive symptomatology and plasma cortisol levels obtained before and after the administration of dexamethasone in 62 affectively ill inpatients. This statistical model for longitudinal studies permits the inclusion of subjects with incomplete data as well as subjects measured at different time points. The most significant relationships were found between decreases in depressive symptoms and decreases in the 8:30 AM predexamethasone and the 4:00 PM postdexamethasone cortisol values. Patients were also classified as responders or nonresponders, and the rate of change in several plasma cortisol measures were separately analyzed for these two groups. No differences in the rate of change in plasma cortisol levels were found between responders and nonresponders. These results suggest that the decreases in cortisol production associated with clinical improvement may be partially explained by a regression toward the mean effect. Some of the possible explanations for these results are discussed.
Adult↗
Personality dimensions in eating disorders and their relevance for subtyping.
Personality dimensions and psychopathological symptoms were assessed in 50 female patients hospitalized for the treatment of anorexia nervosa or bulimia nervosa and in 19 healthy female controls of similar age. Restricting anorexia nervosa patients, who had lost weight by consistently reducing their food intake, reported significantly greater self-control, inhibition of emotionality, and conscientiousness than controls or bulimia nervosa patients, before and after the data were corrected for depressive and eating pathology. Both nonbulimic and bulimic anorexia nervosa patients expressed stronger than normal conformance to moral and family values. On the impulsivity dimension, bulimia nervosa patients scored in the high normal range, whereas bulimic anorexia nervosa patients rated in the low normal range. The results suggest that a personality disposition toward overcontrol and reserve might constitute a risk factor for the restricting type of anorexia nervosa through fostering restrictive behavior toward food and avoidance of personal relationships.
Adolescent↗
Assessment of drug involvement: applications to a sample of physicians in training.
The investigators examined survey data of lifetime and recent drug use in national samples of 2036 senior medical students and 1772 resident physicians to test whether patterns of lifetime drug use could be characterized adequately by a single underlying dimension of 'drug involvement'. The data analysis was based on a two parameter normal item response theory (IRT) model using the marginal maximum likelihood estimation method. The results showed that a single latent dimension of 'drug involvement' characterized individual drug use differences on the following measures: substances ever used, substances used in the previous year or previous month, and the sequential order of first use for each substance. The dimension was equivalent for students and resident physicians, and for both genders. Those who professed 'no religion' tended to be more drug involved. Physicians-in-training with a higher drug involvement score based on lifetime use were more likely: (a) to have used higher-ranking drugs (such as LSD and prescription opiates) in the past year; and (b) to have used a greater number of different drugs during the past month. Subjects first began to use each of the substances in a relatively invariant sequence corresponding to that predicted by the model. The implications of this model for evaluating the drug use histories of physicians-in-training, for identifying subgroups at greater risk for continued drug involvement after the beginning of medical training, and for further psychological, biological, and sociocultural research on the nature of 'drug involvement' are discussed.
Adult↗
Predicting risk for medical malpractice claims using quality-of-care characteristics.
The current fault-based tort system assumes that claims made against physicians are inversely related to the quality of care they provide. In this study we identified physician characteristics associated with elements of medical care that make physicians vulnerable to malpractice claims. A sample of physicians (n = 248) thought to be at high or low risk for claims was surveyed on various personal and professional characteristics. Statistical analysis showed that 9 characteristics predicted risk group. High risk was associated with increased age, surgical specialty, emergency department coverage, increased days away from practice, and the feeling that the litigation climate was "unfair." Low risk was associated with scheduling enough time to talk with patients, answering patients' telephone calls directly, feeling "satisfied" with practice arrangements, and acknowledging greater emotional distress. Prediction was more accurate for physicians in practice 15 years or less. We conclude that a relationship exists between a history of malpractice claims and selected physician characteristics.
Clinical Medicine↗
Random regression models for multicenter clinical trials data.
A random-effects regression model is proposed for the analysis of data arising from multicenter clinical trials. Advantages of the random regression model (RRM) in this context include that it allows for varying numbers of subjects within the different centers, it can assess the influence of variables measured both at the level of the subject and at the level of the center on the subject's clinical outcome, and it controls for and estimates the amount of intracenter variation that is present in the data. An example utilizing data collected in the National Institute of Mental Health schizophrenia collaborative study, where subjects were clustered within nine centers, illustrates the usefulness of the statistical model. Other applications and extensions of RRM within a psychiatric framework are discussed.
Humans↗
Steady-state plasma level prediction for haloperidol from a single test dose.
Due to large interindividual variabilities in kinetics of haloperidol (HPDL), empirically adjusting the dose to achieve steady-state plasma levels (Css) is a time consuming process. We report a method to individualize doses to achieve the desired Css from the observed plasma level 24 hours after a single test dose. Twenty-eight acutely psychotic patients, after up to 2 weeks of inhospital drug washout, received a 15-mg oral "test" dose of HPDL and 24- and 48-hour plasma levels were measured. They were then randomly assigned to empirically determined doses of HPDL (2, 4, or 10 mg b.i.d.) to achieve a low, medium, or high Css. The 24-hour plasma level after the test dose, the final Css, and the dose required to achieve that Css were analyzed by a linear regression model. The log Css in terms of the log dose revealed a strong linear relationship (R2 = .78, n = 28), which was further improved by the addition of the 24-hour log plasma level (R2 = .87).
Female↗
Physical recklessness in adolescence. Trait or byproduct of depressive/suicidal states?
The authors assessed adolescents (264 psychiatric inpatients and 742 high school students) with a new instrument (the Sommerfeldt-Clark Adolescent Recklessness Scale) to test whether adolescents show individual differences on a dimension ranging from physical caution to physical recklessness. The three dimensions that emerged reflect an interest in weapons and military dangers, which we have tentatively labeled "foolhardiness"; the combination of dangerous driving and substance abuse; and involvement with smoking, drug use, and "bad company." The personality traits of "venturesomeness" and "impulsiveness" were significantly correlated with all three recklessness factors. The first two factors showed no significant relationship with patient status, diagnosis of mood disorder, or history of suicidal behavior; the third factor was associated with inpatient status and a history of suicide attempts.
Adolescent↗
Time-related predictors of suicide in major affective disorder.
The authors studied 954 psychiatric patients with major affective disorders and found that nine clinical features were associated with suicide. Six of these--panic attacks, severe psychic anxiety, diminished concentration, global insomnia, moderate alcohol abuse, and severe loss of interest or pleasure (anhedonia)--were associated with suicide within 1 year, and three others--severe hopelessness, suicidal ideation, and history of previous suicide attempts--were associated with suicide occurring after 1 year. These findings draw attention to the importance of 1) standardized prospective data for studies of suicide, 2) assessment of short-term suicide risk factors, and 3) anxiety symptoms as modifiable suicide risk factors within a clinically relevant period.
Adolescent↗
Investigating drug plasma levels and clinical response using random regression models.
The reanalysis of the Riesby dataset using a random regression model indicates a significant effect of DMI plasma measurements on HAM-D scores across the four timepoints of the study. This effect is especially strong when the HAM-D change from baseline score is used in place of the actual HAM-D score at the four timepoints. A significant effect of IMI was not found for either the actual HAM-D score or the HAM-D change from baseline score. An endogenous effect was marginally significant when the actual HAM-D score was used; however, this effect was not observed when the HAM-D change score was used as the dependent measure. There also was evidence of a marginally significant effect due to autocorrelation of the residuals, indicating that the residuals at a given timepoint were related to the residuals from previous timepoints according to a first-order autoregressive process. In contrast, when the repeated measures MANOVA was used to analyze these data, a significant effect of DMI was not observed, since subjects without complete data at all timepoints had to be dropped from the analysis. In longitudinal psychiatric studies where missing data are the rule (rather than the exception), the random regression approach provides an attractive alternative to the traditional methods of analyzing longitudinal data.
Humans↗
Random regression models: a comprehensive approach to the analysis of longitudinal psychiatric data.
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Humans↗
Regression toward the mean: more on the price of beer and the salaries of priests.
Investigators must take great care in studying the temporal association between biological and clinical data. By selecting patients on the basis of deviant levels of a biological parameter, it often is impossible to separate the effect of regression toward the mean from a temporal association of clinical interest. Experimental strategies that focus exclusively on subjects with extreme values are particularly prone to misinterpreting the effects of regression toward the mean as a temporal change in the variable of interest. We cite specific examples of two previous studies of the relationship between the dexamethasone suppression test (DST) and clinical response in depression. Contrary to the conclusions of the investigators, normalization of the DST had no relation to clinical response in the first 5 weeks of treatment. The decrease of post-dexamethasone cortisol levels occurred regardless of clinical response, most likely due to the effect of regression toward the mean.
Antidepressive Agents↗
Response of psychotic and nonpsychotic depressed patients to tricyclic antidepressants.
The response to tricyclic antidepressants (TCAs) is studied in 75 of 121 depressed patients classified as psychotic or nonpsychotic subtypes by Research Diagnostic Criteria. Response was assessed by a clinical global evaluation scale. Of the 75 patients treated with TCAs, 40 (68%) of the nonpsychotic subtype responded in contrast to only 4 (25%) of the psychotic subtype. Adjusting for the effects of chronicity, sex, age, incapacity, agitation, retardation, endogenicity, and the unipolar-bipolar distinction as covariates, it was found that these variables failed to alter the differential response rate of the psychotic and nonpsychotic depressed groups. A literature review of 1054 patients revealed that 67% of the nonpsychotic depressed patients responded to TCAs compared with only 35% of the psychotic depressed patients.
Antidepressive Agents, Tricyclic↗
The relationship between academic performance and severity of depressed mood during medical school.
We employ a structural equation model to examine the relationship between academic performance and depressed mood over 4 years for a single medical school class. Academic performance measures included undergraduate gradepoint average, first- and second-year medical school gradepoint average, full Medical College Admissions Test (MCAT) and total National Boards Part I (NB) scores. Severity of depressed mood was assessed by administering the Beck Depression Inventory two times per year during the first 2 years, and once per year during the last 2 years. Overall there is little reason to think that depressive mood states compromise academic performance during the first 2 years of medical school for the class as a whole. Medical school grades had no direct impact on depressed mood, and mood had no direct impact on grades. There was a non-significant tendency for mood in the months preceding National Boards Part I to influence Board scores, which in turn influenced mood. Students with higher college gradepoint averages consistently reported fewer depressive symptoms throughout medical school. The latter result directs attention to a subgroup of medical students less susceptible to depression, or less prone to admit distress or symptoms. The non-susceptible and/or minimizing qualities of this subgroup merit further investigation.
Achievement↗