Statistics in the medical curriculum.
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Biometry↗
Biomedical subjects
T Colton
Publications and source records attributed to T Colton.
Agreement among raters in assessment of physiologic waveforms recorded by a cardiorespiratory monitor for home use. Collaborative Home Infant Monitoring Evaluation (CHIME) Study Group.
There are numerous reports of cardiorespiratory patterns in infants on home monitors, but no data to determine whether "experts" agree on the description of these patterns. Therefore, we evaluated agreement among four experienced investigators and five trained technicians who assessed independently the same sample of physiologic waveforms recorded from infants enrolled in a multicenter study. The monitor used respiratory inductance plethysmography and recorded waveforms for apnea > or = 16 s or a heart rate < 80 beats/min for > or = 5 s. The investigators and technicians initially assessed 88 waveforms. After additional training, the technicians assessed another 113 additional waveforms. In categorizing waveforms as apnea present or absent, agreement among technicians improved considerably with additional training (kappa 0.65 to 0.85). For categorizing waveforms as having bradycardia present versus absent, the trends were the same. Agreement in measurement of apnea duration also improved considerably with additional training (intraclass correlation 0.33-0.83). Agreement in measurement of bradycardia duration was consistently excellent (intraclass correlation 0.86-0.99). Total agreement was achieved among technicians with additional training for measurement of the lowest heart rate during a bradycardia. When classifying apnea as including > or = 1, > or = 2, > or = 3, or > or = 4 out-of-phase breaths, agreement was initially low, but after additional training it improved, especially in categorization of apneas with > or = 3 or > or = 4 out-of-phase breaths (kappa 0.67 and 0.94, respectively). Although researchers and clinicians commonly describe events based on cardiorespiratory recordings, agreement amongst experienced individuals may be poor, which can confound interpretation. With clear guidelines and sufficient training raters can attain a high level of agreement in describing cardiorespiratory events.
Female↗
Cigarette smoking and the risk of development of lens opacities. The Framingham studies.
OBJECTIVE: To examine the association between cigarette smoking and the incidence of nuclear and non-nuclear lens opacities in members of the Framingham Eye Study Cohort. PARTICIPANTS AND METHODS: Eye examinations were conducted on surviving members of the Framingham Heart Study Cohort from 1973 to 1975 (Framingham Eye Study I) and again from 1986 to 1989 (Framingham Eye Study II). Smoking data, collected biennially since 1948 in the Heart Study, were used to examine the relationship between cigarette smoking and the incidence of lens opacities. Two thousand six hundred seventy-five persons were examined in the Framingham Eye Study I. Our analysis included 660 persons, aged 52 to 80 years, who were free of lens opacities at the first eye examination. RESULTS: During the approximately 12.5 years between eye examinations, lens opacities developed in a total of 381 persons, with nuclear opacities constituting the most frequent type. In logistic regression analyses that controlled for age, sex, education, and diabetes, a significant positive association with increasing duration of smoking and number of cigarettes smoked daily was found for nuclear lens opacities, alone or in combination (test for trend, P < or = .002), but not for nonnuclear opacities (test for trend, P = .62). Among the heavier smokers (persons who smoked > or = 20 cigarettes per day according to 6 or more biennial Framingham Heart Study examinations), 77% were still smoking at the time of the first eye examination. Persons who smoked 20 or more cigarettes per day at the time of the first eye examination were at substantially increased risk for the development of nuclear opacities than nonsmokers (odds ratio, 2.84; 95% confidence interval, 1.46-5.51). There was no apparent excess risk for persons with nonnuclear lens opacities (odds ratio, 1.42; 95% confidence interval, 0.65-3.07). CONCLUSION: This study provides further evidence that cigarette smokers have an increased risk of developing nuclear lens opacities. The risk was greatest for heavier smokers, who tended to be current smokers and who smoked more cigarettes and for a longer duration.
Aged↗
Infant polysomnography: reliability. Collaborative Home Infant Monitoring Evaluation (CHIME) Steering Committee.
Infant polysomnography (IPSG) is an increasingly important procedure for studying infants with sleep and breathing disorders. Since analyses of these IPSG data are subjective, an equally important issue is the reliability or strength of agreement among scorers (especially among experienced clinicians) of sleep parameters (SP) and sleep states (SS). One basic issue of this problem was examined by proposing and testing the hypothesis that infant SP and SS ratings can be reliably scored at substantial levels of agreement, that is, kappa (kappa) > or = 0.61. In light of the importance of IPSG reliability in the collaborative home infant monitoring evaluation (CHIME) study, a reliability training and evaluation process was developed and implemented. The bases for training on SP and SS scoring were CHIME criteria that were modifications and supplements to Anders, Emde, and Parmelee (10). The kappa statistic was adopted as the method for evaluating reliability between and among scorers. Scorers were three experienced investigators and four trainees. Inter- and intrarater reliabilities for SP codes and SSs were calculated for 408 randomly selected 30-second epochs of nocturnal IPSG recorded at five CHIME clinical sites from healthy full term (n = 5), preterm (n = 4), apnea of infancy (n = 2), and siblings of the sudden infant death syndrome (SIDS) (n = 4) enrolled subjects. Infant PSG data set 1 was scored by both experienced investigators and trained scorers and was used to assess initial interrater reliability. Infant PSG data set 2 was scored twice by the trained scorers and was used to reassess inter-rater reliability and to assess intrarater reliability. The kappa s for SS ranged from 0.45 to 0.58 for data set 1 and represented a moderate level of agreement. Therefore, rater disagreements were reviewed, and the scoring criteria were modified to clarify ambiguities. The kappa s and confidence intervals (CIs) computed for data set 2 yielded substantial inter-rater and intrarater agreements for the four trained scorers; for SS, the kappa = 0.68 and for SP the kappa s ranged from 0.62 to 0.76. Acceptance of the hypothesis supports the conclusion that the IPSG is a reliable source of clinical and research data when supported by significant kappa s and CIs. Reliability can be maximized with strictly detailed scoring guidelines and training.
Humans↗
Adult height and risk of breast cancer among white women in a case-control study.
Data from a hospital-based case-control study were analyzed to evaluate the relation of adult height to the risk of breast cancer among white women. The authors compared 5,358 newly diagnosed breast cancer cases and 4,555 controls interviewed from 1976 to 1992 in hospitals located mainly in the United States. Overall, there was no association between stature and risk of breast cancer. In comparison with women whose heights were less than 62 inches (< 158 cm), the adjusted odds ratios were 1.1 (95% confidence interval (Cl) 0.9-1.2), 1.0 (95% Cl 0.9-1.2), 1.0 (95% Cl 0.9-1.1), and 1.0 (95% Cl 0.8-1.2) for women with heights of 62-63, 64-65, 66-67, and > or = 68 inches (equivalent to 158-160, 163-165, 168-170, and > or =173 cm), respectively. There was no consistent evidence of modification of the effect of height by other risk factors. The results suggest that adult stature in white women is not related to the risk of breast cancer.
Adult↗
Parental ages at birth in relation to a daughter's risk of breast cancer among female participants in the Framingham Study (United States).
Data from the Framingham Heart Study, collected in Framingham, MA (United States) during 1948-86, were used to evaluate the relation of parental age at birth to the risk of breast cancer among daughters. After 38 years of follow-up, 149 breast cancer cases occurred among 2,662 women. All but two cases were confirmed by histologic report. The rate of breast cancer increased among daughters with increasing maternal age at birth up to the mid-30s, where the rate levelled off. A similar pattern was observed with paternal age. After adjustment for other confounding factors and paternal age, the rate ratios for breast cancer in daughters whose mothers were aged 26 to 31 years and 32 or more years at their birth, relative to women whose mothers were aged 25 years or younger, were 1.5 (95 percent confidence interval [CI] = 1.0-2.4) and 1.3 (CI = 0.8-2.2), respectively. However, there was no longer an association between paternal age at birth and risk of breast cancer after controlling for maternal age and other risk factors.
Adult↗
A metaanalysis of home uterine activity monitoring.
OBJECTIVE: Our purpose was to assess by metaanalysis the evidence from randomized clinical trials regarding home uterine activity monitoring. STUDY DESIGN: Six randomized controlled trials of home uterine activity monitoring, the same six trials reviewed by the U.S. Preventive Services Task Force on home uterine activity monitoring, were studied. Data were extracted from published reports of the six trials. In addition, unpublished data were obtained by personal communication from the trials' principal investigators. Insofar as possible, the principle of intention-to-treat was maintained. Data regarding twins were handled by use of numbers of pregnancies rather than numbers of infants as sample sizes. Stratified metaanalyses were conducted according to whether the trial did or did not control in study design for the nursing contact factor that accompanies home uterine activity monitoring. In addition, stratified metaanalyses were conducted for singleton and twin pregnancies. The four outcomes investigated were incidence of preterm birth, incidence of preterm labor combined with cervical dilatation > 2 cm, infant referral to the intensive care unit, and mean birth weight. RESULTS: Overall, for all pregnancies home uterine activity monitoring was associated with a statistically significant reduction of 52% in risk of preterm labor combined with cervical dilatation > 2 cm (relative risk = 0.48, p = 0.001) and a statistically significant increase of 86 gm in mean birth weight (p = 0.038). When stratified by singleton or twin pregnancy, the pooled results generally differed by strata. Among singleton pregnancies, home uterine activity monitoring was associated with a statistically significant reduction of 24% in risk of preterm birth (relative risk 0.76, p = 0.037) and a statistically significant increase of 126 gm in mean birth weight (p = 0.009). Among twin pregnancies, there was a statistically significant effect of home uterine activity monitoring with a reduction of 56% in risk of preterm labor combined with cervical dilatation > 2 cm (relative risk 0.44, p = 0.005). There were no statistically significant effects found overall and in any stratum with regard to infant referral to the intensive care unit. Metaanalyses of studies that controlled in design for the nursing contact factor that accompanies home uterine activity monitoring showed either no difference or stronger pooled effects compared with metaanalyses of those studies that did not control for nursing contact. This suggests that the potential bias attributed to the nursing contact feature that accompanies home uterine activity monitoring is not as appreciable as home uterine activity monitoring critics have suggested. CONCLUSIONS: Metaanalysis of existing clinical trial evidence regarding home uterine activity monitoring reveals statistically significant benefits of home uterine activity monitoring. Of the outcomes investigated, home uterine activity monitoring is associated with reductions in risks of preterm birth (in singleton pregnancies only) and preterm labor combined with cervical dilatation > 2 cm, as well as with increased mean birth weight (in singleton pregnancies only).
Female↗
Effects of antihypertensive medications on quality of life in elderly hypertensive women.
The impact of antihypertensive medications on the quality of life of elderly hypertensive women has rarely been systematically evaluated in large clinical trials using drugs from the new generations of pharmaceutic preparations. We carried out a multicenter, randomized double-blind clinical trial with 309 hypertensive women aged 60 to 80 years to assess effects of atenolol, enalapril, and isradipine on measures of quality of life over a 22-week period. The patients had mild to moderate hypertension. Hydrochlorothiazide was added to treatment if monotherapy was inadequate in lowering blood pressure. At the conclusion of the trial the three drug groups did not differ in degree of reduction of diastolic blood pressure or in supplementation with hydrochlorothiazide. Over the 22-week trial, linear trend analysis showed no differences between the treatment groups in change from baseline on quality of life measures of well-being, physical status, emotional status, cognitive functioning, and social role participation. Regarding each of 33 physical side effects over the 22 weeks, we found no general difference between atenolol, enalapril, and isradipine groups on measures of change in distress over symptoms except for enalapril patients who worsened in distress over cough (P = .001) and atenolol patients who worsened in distress over dry mouth (P = .014). Centering on three medications that are relatively new additions to the armamentarium for blood pressure control, the findings underline the increasing opportunities for the physician to select drugs that can control blood pressure while maintaining the quality of life of elderly hypertensive women.
Aged↗
A controlled trial of diazepam administered during febrile illnesses to prevent recurrence of febrile seizures.
BACKGROUND: Phenobarbital, once widely prescribed to prevent febrile seizures, is now in disfavor because of its side effects and lack of efficacy. Diazepam, administered only during episodes of fever, may be a safe, effective agent to prevent the recurrence of febrile seizures. METHODS: We conducted a randomized, double-blind, placebo-controlled trial among 406 children (mean age, 24 months) who had at least one febrile seizure. Diazepam (0.33 mg per kilogram of body weight) or placebo was administered orally every eight hours during all febrile illnesses. RESULTS: During a mean follow-up of 1.9 years (a period during which 90 percent of febrile seizures recur), our intention-to-treat analysis showed a reduction of 44 percent in the risk of febrile seizures per person-year with diazepam (relative risk = 0.56; 95 percent confidence interval, 0.38 to 0.81; P = 0.002). A survival analysis of the length of time to the first recurrent febrile seizure did not show a significant difference between the treatment groups (P = 0.064 by the log-rank test), but after adjustment for covariates, diazepam was found to have a benefit (P = 0.027 by Cox regression analysis). An analysis restricted to children who had seizures while actually receiving the study medication (7 in the diazepam group and 29 in the placebo group) showed an 82 percent reduction in the risk of febrile seizures with diazepam (relative risk = 0.18; 95 percent confidence interval, 0.09 to 0.37; P < 0.001). Of the 153 children who took at least one dose of diazepam, 39 percent had ataxia, lethargy, or irritability or at least one other moderate side effect that was reversed after a reduction in the dose. There were no severe side effects. CONCLUSIONS: Oral diazepam, given only when fever is present, is safe and reduces the risk of recurrent febrile seizures.
Administration, Oral↗
Breast cancer in mothers prescribed diethylstilbestrol in pregnancy. Further follow-up.
OBJECTIVE: Further assessment of the long-term risk of breast cancer associated with diethylstilbestrol (DES) during pregnancy. DESIGN: Follow-up continuation through June 1, 1989, of a historical cohort of DES-exposed and unexposed mothers ascertained by review of obstetric records. PARTICIPANTS: Totals of 3029 each of DES-exposed and unexposed mothers who had delivered live babies at four centers in the United States during 1940 through 1960. Questionnaires were returned for 92.6% of the DES-exposed and 88.8% of the unexposed women. MAIN OUTCOME MEASURES: Breast cancer incidence and mortality assessed from returned questionnaires and review of medical records and death certificates. MAIN RESULTS: The relative rate of breast cancer associated with DES exposure, after adjustment for demographic and reproductive variables, was 1.35 (95% confidence interval, 1.05 to 1.74). For 30 years or more following exposure, the relative rate was not appreciably higher (relative rate, 1.33; 95% confidence interval, 0.95 to 1.87) than that in earlier periods. Surveillance and increased detection seemed unlikely explanations for the increased risk, since DES-exposed women had excesses of both large and small breast cancers and the two cohorts reported similar breast cancer detection practices. A history of miscarriage before first term delivery was not associated with breast cancer occurrence. CONCLUSION: Exposure to DES during pregnancy is associated with a modest but statistically significant increased risk of breast cancer. Contrary to prior indications, the risk does not appear to increase greatly over time. The findings are sufficient to exclude the possibility of a doubling of risk for the period of 30 or more years following exposure.
Abortion, Spontaneous↗
Wartime mosquito-eradication effort in World War II was turned into what is today the Centers for Disease Control.
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Centers for Disease Control and Prevention, U.S.↗
Designing a biological monitoring program to assess community exposure to chromium: conclusions of an expert panel.
The possible benefits of biological monitoring of large groups of people potentially exposed to environmental contaminants has become an area of much interest in recent years. Because chromite-ore processing residue has been found in some soils in northern New Jersey, urinary chromium monitoring of people in the community was evaluated as a potentially useful tool. In an attempt to identify those who could be exposed and to quantify the magnitude of exposure to the chromium in these soils, the New Jersey Department of Health (NJDOH) initiated a public health screening project. In 1992, the NJDOH proposed to evaluate over 4000 people who lived or worked near these sites. Volunteers were administered a questionnaire and were given a limited physical examination, and a single spot urine sample was collected. Because of the difficulties in using urinary chromium to assess low-level exposure and the potential implications of any regulatory decisions that could be based on the results of this project, a panel of experts was convened to evaluate the protocol. The panel consisted of five scientists and physicians with expertise in toxicology, dermatology, epidemiology, biological monitoring, and analytical chemistry. Like a World Health Organization group, the panel concluded that although urine biomonitoring can be useful in evaluating high levels of exposure to chromium, it is not reliable for assessing low-level exposure similar to that which may have occurred in northern New Jersey. The panel also noted that when urinary biomonitoring is to be used to assess the public's possible exposure, a large number of precautions must be taken to ensure the accuracy and usefulness of the results. The single most important recommendation was to collect a second, and perhaps a third, spot urine (or 24-h urine) sample before concluding that a person may be routinely overexposed. These suggestions are applicable to designing a biomonitoring program for nearly any environmental contaminant to which a community may be exposed. A review of scientific literature associated with biological monitoring of chromium is provided.
Absorption↗
Increased risk of profound weight loss among women exposed to diethylstilbestrol in utero.
We surveyed 1711 women exposed to diethylstilbestrol in utero, and 919 women not exposed, concerning lifetime weight loss histories. The prevalence of a history of unexplained profoundly low body weight (weight less than or equal to 80% of expected weight for age, sex, and height) was 18.7 per 1000 in the exposed group compared to 3.3 per 1000 in the unexposed group; a 5.72 to 1 ratio of increased risk.
Adult↗
Issues in the early termination of the aspirin component of the Physicians' Health Study. Data Monitoring Board of the Physicians' Health Study.
The Physicians' Health Study is a randomized, double-blind, placebo-controlled prevention trial of 22,071 US physicians, using a factorial design to evaluate the role of aspirin in the prevention of cardiovascular mortality and beta carotene in the reduction of cancer incidence. After approximately 5 years of follow-up, the aspirin component was terminated, 3 years ahead of schedule. Several factors were considered in the decision to terminate, including a cardiovascular mortality rate markedly lower than expected in both aspirin and placebo subjects, precluding the evaluation of the primary aspirin hypothesis, and a highly significant (P < .00001) and impressive (44%) reduction in the risk of first myocardial infarction in the aspirin group. Issues in the decision to terminate are described in this report.
Adult↗
Cancer surveillance of Veterans in Massachusetts, USA, 1982-1988.
This surveillance study is a follow-up to previous findings of elevated soft tissue sarcoma mortality in Massachusetts Vietnam veterans compared to other veterans. The roster of veterans was compiled from Massachusetts residents who received a state bonus for military service in the period 1958-1973. This computerized list was linked to the central files of the Massachusetts Cancer Registry and cases diagnosed between 1982 and 1988 were identified. Odds ratios (ORs) for several cancer sites were computed; only that for soft tissue sarcoma incidence was significantly elevated in Vietnam veterans compared to other veterans (OR = 3.08; 95% confidence interval: (CI) 1.07-8.73). Kaposi's sarcoma cases who were also AIDS patients were excluded from the analysis. Non-Hodgkin's lymphoma was also investigated but was not significantly elevated in these surveillance data. Sources of bias are discussed and recommendations for continued surveillance and follow-up studies are made.
Adult↗
The 'power' of sound statistics.
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Humans↗
A two-period crossover design for the comparison of two active treatments and placebo.
This paper discusses a two-period crossover design for the comparison of two active treatments (A and B) and placebo (P) for relief of recurrent symptoms of a chronic health disorder. It is based on blocks of ten patients for which the treatment sequences A:B and B:A are each assigned to three patients and the sequences A:P, P:A, B:P, and P:B are each assigned to one patient; thus, treatment periods have a 2:2:1 allocation for A, B, and P. The principal model for analysis of this design involves additive subject effects, period effects, and treatment effects. Analysis of within-patient differences provides an estimate of the comparison between active treatments with variance (2vw/7r) and an estimate of the comparison between an active treatment and placebo with variance (4vw/7r); here vw is the within-patient variance and r is the number of blocks of ten patients. Analyses which address carryover effects and treatment effects adjusted for carryover effects are also described. An example using simulated data on relief of recurrent gastrointestinal pain illustrates the methodology.
Chronic Disease↗
Prevention of childhood injuries: evaluation of the Statewide Childhood Injury Prevention Program (SCIPP).
We evaluated the effectiveness of a community-based injury prevention program designed to reduce the incidence of burns, falls in the home, motor vehicle occupant injuries, and poisonings and suffocations among children ages 0-5 years. Between September 1980 and June 1982, we implemented five injury prevention projects concurrently in nine Massachusetts cities and town; five sites, matched on selected demographic characteristics, were control communities. An estimated 42 percent of households with children ages 0-5 years were exposed to one or more of the interventions over the two-year period in the nine communities. Participation in safety programs increased three-fold in the intervention communities and two-fold in the control communities. Safety knowledge and practices increased in both intervention and control communities. Households that reported participatory exposure to the interventions had higher safety knowledge and behavior scores than those that received other community exposure or no exposure to intervention activities. We found a distinct reduction in motor vehicle occupant injuries among children ages 0-5 years in the intervention compared with control communities, associated with participatory exposure of about 55 percent of households with children ages 0-5 years. We have no evidence that the coordinated intervention programs reduced the other target injuries--although exposure to prevention messages was associated with safety behaviors for burns and poisonings.
Accident Prevention↗