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Methods of sample size and power calculations are reviewed for the most common study designs. The sample size and power equations for these designs are shown to be special cases of two generic formulae for sample size and power calculations. A computer program is available that can be used for studies with dichotomous, continuous, or survival response measures. The alternative hypotheses of interest may be specified either in terms of differing response rates, means, or survival times, or in terms of relative risks or odds ratios. Studies with dichotomous or continuous outcomes may involve either a matched or independent study design. The program can determine the sample size needed to detect a specified alternative hypothesis with the required power, the power with which a specific alternative hypothesis can be detected with a given sample size, or the specific alternative hypotheses that can be detected with a given power and sample size. The program can generate help messages on request that facilitate the use of this software. It writes a log file of all calculated estimates and can produce an output file for plotting power curves. It is written in FORTRAN-77 and is in the public domain.
Clinical decision making is under increased scrutiny due to concerns about the cost and quality of medical care. Variability in physician decision making is common, in part because of deficiencies in the knowledge base, but also due to the difference in physicians' approaches to clinical problem solving. Evaluation of patient prognosis is a critical factor in the selection of therapy, and careful attention to methodology is essential to provide reliable information. Randomized controlled clinical trials provide the most solid basis for the establishment of broad therapeutic principles. Because randomized studies cannot be performed to address every question, observational studies will continue to play a complementary role in the evaluation of therapy. Randomized studies in progress, meta analyses of existing data, and increased use of administrative and collaborative clinical data bases will improve the knowledge base for decision making in the future.
The 1988 National Maternal and Infant Health Survey was conducted by the National Center for Health Statistics to study factors related to poor pregnancy outcome, such as adequacy of prenatal care; inadequate and excessive weight gain during pregnancy; maternal smoking, drinking, and drug use; and pregnancy and delivery complications. The survey is a nationally representative sample of 11,000 women who had live births, 4000 who had late fetal deaths, and 6000 who had infant deaths in 1988. Mothers were mailed questionnaires based on information from certificates of live birth, reports of fetal death, and certificates of infant death. Information supplied by the mother, prenatal care providers, and hospitals of delivery was linked with the vital records to expand knowledge of maternal and infant health in the United States. Data collection from the Longitudinal Followup of mothers in the survey began in January 1991. It provides information on health and development of low- and very low-birthweight babies, child care and safety, maternal health, maternal depression, and plans for adoption and foster care. Both surveys will provide useful data for clinicians in maternal and child health.
The pharmacokinetic and pharmacodynamic interaction between caffeine and phenylpropanolamine has been investigated in six normal subjects in a double-blind, placebo-controlled, Latin-square design study. After 3 days on a 100 mEq sodium, xanthine-free diet, fasting subjects were placed in a supine position and were given 25 mg phenylpropanolamine and placebo, 250 mg caffeine and placebo, or 25 mg phenylpropanolamine and 250 mg caffeine in random order. Blood pressure, pulse, plasma renin activity, and plasma catecholamine levels were measured before and for 3 hours after drug administration. Plasma and urinary phenylpropanolamine, caffeine, and caffeine metabolite levels were measured serially for 48 hours. Coadministration of caffeine and phenylpropanolamine produced an additive increase in blood pressure. This effect could not be explained by any pharmacokinetic interaction between the two drugs and occurred even though phenylpropanolamine attenuated the epinephrine and renin response to caffeine. These data suggest that a clinically relevant interaction between caffeine and phenylpropanolamine does occur in drug-free subjects and that this interaction cannot be explained by a mechanism involving the sympathetic or renin-angiotensin systems.
Describes the application to community issues of the meta-analytic research strategies increasingly used in many field of psychology. First, we highlight the potential value of meta-analysis to community research. Second, we describe six major steps involved in conducting an effective meta-analysis. These steps include formulating the initial research question(s), locating relevant studies, abstracting critical information from each study, and presenting, analyzing, and interpreting the resultant data. In this guide, the major aspects of meta-analysis are discussed with particular emphasis on the procedures that are most critical to the validity of its conclusions. Greater familiarity with the techniques, issues, and potential of meta-analysis may stimulate investigators to make more effective use of this powerful approach to integrating research in community psychology.
The toxicities of chemotherapy continue to hamper dose escalation of specific chemotherapeutic agents. The impact of dose intensification upon survival will be assessed as clinical studies continue. Strategies to support chemotherapy dose intensification include BMT, use of CSFs and antiemetic drug combinations. Advances in symptom management will hopefully enhance quality of life for patients, whereas the development of chemoprotectant agents may allow specific organ toxicities to be avoided.
We derived a model of appraisal, coping, and adaptation in patients with rheumatoid arthritis (RA) from the more general theory of Lazarus and Folkman (1984) and examined this model using a longitudinal data set spanning 4 years and involving 239 RA patients (of whom 157 contributed to the primary analyses, with the remainder contributing to various follow-up analyses). This model attempted to identify the short- and long-term adaptational consequences of coping as well as the antecedents (appraisals, beliefs, social support, disease activity, etc.) that promote particular coping styles. Interrelations among the variables were examined using path-analytic techniques. Many observed relations were consistent with the model. Significant relations were subjected to more stringent analyses examining the ability of hypothesized causal variables to predict changes in outcome variables 1 year later. These analyses provided additional support for many observed relations and suggested the existence of a vicious cycle involving helplessness appraisals, passive coping with pain, and psychosocial impairment that promotes maladaptation in the face of RA. Theoretical implications, strengths, and limitations of the study are discussed.
High-dose cytosine arabinoside (HDAC) is used to treat adults with acute and chronic leukemia and non-Hodgkin's lymphoma. Although HDAC is associated with various toxicities, cutaneous toxicity in particular leads to alterations in comfort, interference with daily living activities, and increased risk of infection. The incidence of cutaneous toxicity ranges from 3%-72%. A review of the literature revealed a variety of terms describing this toxicity, which begins as erythema and progresses to painful swelling, bullae formation, and desquamation. The etiology is unclear, and the severity is related to the number of consecutive doses. Interventions specific to prevention and treatment of this toxicity were found to be minimal, with no interventions scientifically examined. The challenge for nurses is to explore measures that will minimize the complications, treat the manifestations, and document the impact of these problems on quality of life.