Biomedical subjects

P A Charpentier

Publications and source records attributed to P A Charpentier.

10 recordsLinked to original sources

PubMed2001

An algorithm for prospective individual matching in a non-randomized clinical trial.

A method is described to achieve balance across prognostic factors in intervention trials for which randomized allocation to treatment group is not possible. The method involves prospective individual matching of patients that have already been assigned to treatment groups. Data can be analyzed using methods appropriate for prospective matched cohort studies. Successful implementation depends on the number and complexity of factors to be matched, and on the number of available control patients. Simulation studies suggest that, in order to yield satisfactory match rates and to reduce costs associated with screening unmatched controls, no more than three prognostic factors should generally be considered. Baseline prognostic indices, incorporating information from multiple variables, provide effective matching factors. The implementation of the method in a successful clinical trial, the Delirium Prevention Trial, is discussed. In that study, treatment group was determined by hospital admission to either an intervention floor or to one of two usual care hospital floors. The ratio of available control to intervention patients was 1.3, and 95% of the eligible intervention floor patients were successfully matched to control floor patients. Excellent balance was demonstrated for non-matching factors, due in part to the use of a composite baseline risk score as a matching factor. In addition, external validity is enhanced because most eligible intervention patients are enrolled as they present. The methods outlined in this report provide a methodologically rigorous alternative for achieving balance across treatment groups, with respect to important prognostic factors, in non-randomized clinical trials, and will have broad applicability in the numerous situations in which randomization is not possible.

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PubMed2000

PTEVAL: a computerized home-based physical therapy intervention instrument.

The determination of physical therapy treatment protocols, based on an in-home evaluation of a patient, is a complex task. The specific rules for treatment indications are individually simple, but numerous and hence time-consuming and prone to error using pencil-and-paper methods. This paper describes PTEVAL, a computerized Point-of-Care instrument designed to support the intervention protocols of an ongoing clinical trial. With appropriate modifications and extensions, PTEVAL can be a model for instruments used in clinical practice.

Activities of Daily Living↗

PubMed1999

A multicomponent intervention to prevent delirium in hospitalized older patients.

BACKGROUND: Since in hospitalized older patients delirium is associated with poor outcomes, we evaluated the effectiveness of a multicomponent strategy for the prevention of delirium. METHODS: We studied 852 patients 70 years of age or older who had been admitted to the general-medicine service at a teaching hospital. Patients from one intervention unit and two usual-care units were enrolled by means of a prospective matching strategy. The intervention consisted of standardized protocols for the management of six risk factors for delirium: cognitive impairment, sleep deprivation, immobility, visual impairment, hearing impairment, and dehydration. Delirium, the primary outcome, was assessed daily until discharge. RESULTS: Delirium developed in 9.9 percent of the intervention group as compared with 15.0 percent of the usual-care group, (matched odds ratio, 0.60; 95 percent confidence interval, 0.39 to 0.92). The total number of days with delirium (105 vs. 161, P=0.02) and the total number of episodes (62 vs. 90, P=0.03) were significantly lower in the intervention group. However, the severity of delirium and recurrence rates were not significantly different. The overall rate of adherence to the intervention was 87 percent, and the total number of targeted risk factors per patient was significantly reduced. Intervention was associated with significant improvement in the degree of cognitive impairment among patients with cognitive impairment at admission and a reduction in the rate of use of sleep medications among all patients. Among the other risk factors per patient there were trends toward improvement in immobility, visual impairment, and hearing impairment. CONCLUSIONS: The risk-factor intervention strategy that we studied resulted in significant reductions in the number and duration of episodes of delirium in hospitalized older patients. The intervention had no significant effect on the severity of delirium or on recurrence rates; this finding suggests that primary prevention of delirium is probably the most effective treatment strategy.

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PubMed1998

Prospective individual matching: covariate balance and power in a comparative study.

In phase II to phase IV studies, randomization has gained widespread acceptance as a methodologic tool for the allocation of patients to treatment. However, randomization is not always feasible. At times, the treatment intervention occurs universally throughout one or more units (for example, a hospital unit), while the control therapy is the only intervention provided in other units. Patients may arrive randomly at a unit, based solely on availability of the unit to accept new subjects. Thus, the treatment assignment process is out of the investigator's control and not subject to selection bias. We describe a prospective individual matching procedure through which one can achieve balanced allocation of subjects to treatment groups in this comparative study setting. In this paper, we compare balance of baseline covariates and power for this design, in which the subject is selected at random and assigned to a treatment group, and the traditional randomized block design, in which the treatment is chosen at random and assigned to a subject. We show that the prospective individual matching procedure compares favourably to the traditional randomized blocked design with respect to both baseline covariate comparability and statistical power.

Analysis of Variance↗

PubMed1997

The informed consent process in older patients who developed delirium: a clinical epidemiologic study.

PURPOSE: Delirium, defined as an acute, fluctuating disorder of attention and cognition, is a serious and increasingly common problem for hospitalized older persons. Delirium poses unique ethical challenges for the informed consent process, notably the preservation of patient autonomy in the face of potentially fluctuating decision-making capacity. To clarify these issues, we examined the informed consent process in a group of hospitalized older patients who developed delirium. PATIENTS: Eighty-four hospitalized patients aged >70 years who developed delirium during hospitalization at a large urban teaching hospital. METHODS: We conducted a clinical epidemiologic investigation of informed consent in 173 medical and surgical procedures performed in 84 patients. Clinical researchers carried out detailed cognitive evaluation of patients on or near the consent date. A separate blinded researcher extracted medical record information on the procedures and informed consent process variables. RESULTS: Of 173 procedures, 33 (19%) had no documentation of any consent, and 34 (20%) used surrogate consent. There were no documented assessments of competency/ decisional capacity; cognitive assessments were done in 7 (4%) cases, and legal consults in 2 (1%) cases. Discussion of potential risks of the procedure with patient or surrogate were documented in 61 (35%) cases. In multivariable analysis, independent predictors for failure to obtain consent were presence of delirium (adjusted odds ratio [OR] = 2.7, 95% confidence interval [CI] 1.3, 5.3) and less invasive procedure (OR = 5.0, CI 2.0, 12.8). Although cognitive impairment predicted surrogate use, we found that 47% of cases with substantial impairment did not involve use of a surrogate, whereas surrogates signed for 4% of cases with normal mental status near the time of consent. CONCLUSIONS: Our results highlight the ethical challenges that delirium poses for the informed consent process, including the high rate of no consent, lack of cognitive and decisional capacity assessment, and inconsistent surrogate use.

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PubMed1996

Precipitating factors for delirium in hospitalized elderly persons. Predictive model and interrelationship with baseline vulnerability.

OBJECTIVES: To prospectively develop and validate a predictive model for delirium based on precipitating factors during hospitalization, and to examine the interrelationship of precipitating factors and baseline vulnerability. DESIGN: Two prospective cohort studies, in tandem. SETTING: General medical wards, university teaching hospital. PATIENTS: For the development cohort, 196 patients aged 70 years and older with no delirium at baseline, and for the validation cohort, 312 comparable patients. MAIN OUTCOME MEASURE: New-onset delirium by hospital day 9, defined by the Confusion Assessment Method diagnostic criteria. RESULTS: Delirium developed in 35 patients (18%) in the development cohort. Five independent precipitating factors for delirium were identified; use of physical restraints (adjusted relative risk [RR], 4.4; 95% confidence interval [CI], 2.5 to 7.9), malnutrition (RR, 4.0; 95% CI, 2.2 to 7.4), more than three medications added (RR, 2.9; 95% CI, 1.6 to 5.4), use of bladder catheter (RR, 2.4; 95% CI, 1.2 to 4.7), and any iatrogenic event (RR, 1.9; 95% CI, 1.1 to 3.2). Each precipitating factor preceded the onset of delirium by more than 24 hours. A risk stratification system was developed by adding 1 point for each factor present. Rates of delirium for low-risk (0 points), intermediate-risk (1 to 2 points), and high-risk groups (> or equal to 3 points) were 3%, 20%, and 59%, respectively (P < .001). The corresponding rates in the validation cohort, in which 47 patients (15%) developed delirium, were 4%, 20%, and 35%, respectively (P < .001). When precipitating and baseline factors were analyzed in cross-stratified format, delirium rates increased progressively from low-risk to high-risk groups in all directions (double-gradient phenomenon). The contributions of baseline and precipitating factors were documented to be independent and statistically significant. CONCLUSIONS: A simple predictive model based on the presence of five precipitating factors can be used to identify elderly medical patients at high risk for delirium. Precipitating and baseline vulnerability factors are highly interrelated and contribute to delirium in independent substantive, and cumulative ways.

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PubMed1996

A database model for studies of cocaine-dependent pregnant women and their families.

The database management functions for the Mothers Project are arranged into administrative and analytic task groups, and separate systems are devised for each. The task groups can be distinguished not only by differences in data structure but also by interface requirements. The administrative database system uses a relational database technology, whereas the analytic database system employs more traditional flat-file methods. Although the database management systems are complex, they are based on standard database practices, used in widely available software packages, and run on inexpensive desktop computing equipment.

Cocaine↗

PubMed1995

Self-esteem and neuroendocrine response to challenge: MacArthur studies of successful aging.

The role of self-esteem in modulating patterns of neuroendocrine response to challenge at older ages was examined in 16 healthy 70-yr-olds. Responses to two challenges were examined: (1) a driving simulation designed to reflect a 'real life' challenge situation; and (2) a pharmacologic, corticotropin-releasing-hormone (CRH) challenge (1 micrograms/kg). Both challenges evoked significant elevations in cortisol and adrenocorticotropic hormone (ACTH). Levels of self-esteem were significantly and negatively associated with peak elevations in cortisol in response to the driving simulation challenge (r = -0.51, p = 0.04). ACTH responses showed similar trends (r = -0.41, p = 0.12). Self-esteem levels were not correlated with responses to the CRH challenge. These data indicate that psychological characteristics such as self-esteem may play a role in modulating patterns of neuroendocrine response to cognitive/behavioral challenges in everyday life in older individuals.

Activities of Daily Living↗

PubMed1995

Behavioral and psychosocial predictors of physical performance: MacArthur studies of successful aging.

BACKGROUND: Performance-based measures of physical performance are examined for an older cohort of relatively high-functioning men and women. The influences of baseline behavioral, social, and psychological characteristics on patterns of change in performance over 2.5 years are examined. METHODS: A cohort of relatively high-functioning men and women, aged 70-79, identified in 1988 by subsampling from three community-based studies on the basis of physical and cognitive function. Baseline assessments included physical performance, sociodemographic characteristics, health status, and behavioral, social, and psychological characteristics. A summary measure of physical performance was developed from tests of balance, gait, lower body strength and coordination, and manual dexterity. In-home assessments were repeated at follow-up in 1991. RESULTS: Linear regression models were used to identify significant behavioral, social, and psychological predictors of better performance at follow-up, controlling for known sociodemographic and health status predictors. Significant, independent associations with better performance were found for participation in moderate and/or strenuous exercise activity and greater frequency of emotional support from social networks, particularly among those reporting low frequency of instrumental support. These effects remained significant independent of incident health conditions during follow-up. None of the psychological characteristics was a significant predictor. CONCLUSIONS: Maintenance of better physical performance within a high-functioning cohort is influenced by prior exercise behavior and social network emotional support. Observed patterns of both decline and improvement in performance suggest that older age is not uniformly associated with declines. Predictors of better performance identified here may offer potential for effective interventions to promote more successful aging.

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PubMed1994

Predicting changes in physical performance in a high-functioning elderly cohort: MacArthur studies of successful aging.

BACKGROUND: Performance-based measures of physical performance were examined for an older cohort of relatively high-functioning men and women. Relationships between baseline physical performance and sociodemographic and health status characteristics were also examined. Three-year pattern changes in performance are described, and sociodemographic and health status predictors of change are investigated. METHODS: A cohort of relatively high-functioning men and women, aged 70-79, was identified in 1988 by subsampling from three community-based studies on the basis of physical and cognitive function. Baseline in-home assessments included tests of physical performance and measurement of sociodemographic characteristics and health status. A summary measure of physical performance was developed from tests of balance, gait, lower body strength and coordination, and manual dexterity. In-home assessments were repeated at follow-up in 1991. RESULTS: Better physical performance at baseline was more common among males, Whites, those reporting higher income and education, and those with fewer chronic conditions. In linear regression models, declines in performance were predicted by older age, lower income, higher education, relative weight and blood pressure, lower peak expiratory flow, prevalent diabetes and incident health conditions and hospitalizations during follow-up. Improvements in performance were also observed; the only significant association was with race (i.e., being Black). CONCLUSIONS: Declines in physical performance within a high-functioning cohort are predictable from sociodemographic and health status characteristics. The patterns of both decline and improvement in performance observed in this cohort suggest that older age is not uniformly associated with declines, indicating the potential for effective interventions to promote more successful aging.

Activities of Daily Living↗