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Biomedical subjects

C S Berkey

Publications and source records attributed to C S Berkey.

At least 37 records · Page 2Linked to original sources
PubMed1998

Blood pressure in adolescence and early adulthood related to obesity and birth size.

OBJECTIVE: Obesity is an established risk factor for higher systolic (SBP) and diastolic (DBP) blood pressure in adolescence and early adulthood, but birth size may also have a role. We analyzed the effects of adolescent and adult obesity and birth size on BP in the young adult. RESEARCH METHODS AND PROCEDURES: In a prospective longitudinal study, anthropometric measurements were obtained at birth on 67 boys and 67 girls born in Boston. Their body mass indices (BMI) and BP were recorded 17 years and 30 years later. RESULTS: For women, adolescent and early adult obesity appeared to be the stronger determinants of higher BP, although smaller head and chest circumferences at birth may also be related. We found some evidence of birth (ponderal index [PI] and head circumference) anthropometric influences on age 17 BP levels in boys. By age 30, body mass variables were the dominant predictors of male BP levels. Female BMI at age 17 was positively correlated with birth adiposity (PI), but BMI at 30 was related only to age 17 BMI. Similarly, male BMI at 17 years was higher for those who weighed more at birth, but BMI at 30 years was again related only to age 17 BMI. DISCUSSION: We conclude that adult weight and weight gain are the major determinants of adult BP.

Adipose Tissue↗
PubMed1997

Dexamethasone as adjunctive therapy in bacterial meningitis. A meta-analysis of randomized clinical trials since 1988.

OBJECTIVE: To evaluate the effectiveness of dexamethasone in bacterial meningitis in the subcategories of causative organism and timing and nature of antibiotic therapy. DATA SOURCES: MEDLINE, HEALTHLINE, and AIDSLINE were searched with the Medical Subject Headings "dexamethasone" and "meningitis" in any language. Bibliographies, conference abstracts, and the authors of identified studies were consulted. STUDY SELECTION: Randomized, concurrently controlled trials of dexamethasone therapy in childhood bacterial meningitis published from 1988 to November 1996 were selected. Of 16 studies identified, 5 were not eligible. DATA EXTRACTION: Data were extracted by means of standard outcomes in a protocol sent to all principal authors. DATA SYNTHESIS: Random-effects meta-analysis models were used to obtain summary estimates. As the incidence of severe hearing loss differed significantly by organism among control subjects, organism-specific estimates were used. In Haemophilus influenzae type b meningitis, dexamethasone reduced severe hearing loss overall (combined odds ratio [OR], 0.31; 95% confidence interval [CI], 0.14-0.69). Similar ORs were obtained after studies were stratified by the timing of administration of dexamethasone (before or with antibiotics vs later) or by type of antibiotic (cefuroxime vs other). In pneumococcal meningitis, only studies in which dexamethasone was given early suggested protection, which was significant for severe hearing loss (combined OR, 0.09; 95% CI, 0.0-0.71) and approached significance for any neurological or hearing deficit (combined OR, 0.23; 95% CI, 0.04-1.05). For all organisms combined, the pooled OR suggested protection against neurological deficits other than hearing loss but was not significant (OR, 0.59; 95% CI, 0.34-1.02). Outcomes were similar in studies that used 2 vs more than 2 days of dexamethasone therapy. Adverse effects were not significantly increased with dexamethasone except for secondary fever. The incidence of gastrointestinal tract bleeding increased with longer duration of dexamethasone treatment (0.5% in controls, 0.8% with 2 days of treatment, 3.0% with 4 days of treatment). CONCLUSIONS: The available evidence on adjunctive dexamethasone therapy confirms benefit for H influenzae type b meningitis and, if commenced with or before parenteral antibiotics, suggests benefit for pneumococcal meningitis in childhood. Limiting dexamethasone therapy to 2 days may be optimal.

Adolescent↗
PubMed1997

Effects of body fat on ventilatory function in children and adolescents: cross-sectional findings from a random population sample of school children.

Childhood obesity is associated with a range of adverse consequences, and the prevalence is increasing in developed nations. Most of the literature on obesity and ventilatory function in children concerns samples selected for gross obesity with relatively little detail available from random population samples. This report examines the effect of total body fat as a percentage of weight (TBF%) on ventilatory function in a nationally representative sample of 2,464 Australian school children aged 9, 12, and 15 years. Forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were used as measures of ventilatory function. TBF% was estimated from skinfold thickness measurements. Ventilatory function was adjusted (for height and then for both height and weight) using linear regression on a logarithmic scale. Adjustment was performed within separate strata of age and gender. Analysis of covariance was used for hypothesis testing. Height-adjusted FVC and FEV1 values increased significantly with increasing weight within each age and gender group and for all subjects combined (P < 0.0001). The effect of TBF% independent of lean tissue was examined using FVC and FEV1 values adjusted for both height and weight, because body weight measures both lean and fat mass. Adjusted FVC and FEV1 values decreased significantly with increasing TBF% within each age and gender group and for all subjects combined (P < 0.0001). Ventilatory function decreased with increasing proportions of body fat. This is consistent with previous findings on lean tissue mass and ventilatory function. Although the magnitude of the effect was relatively small in clinical terms, from a public health perspective our findings indicate yet another adverse consequence of childhood obesity.

Adolescent↗
PubMed1997

Cancer incidence and mortality: the priority of screening frequency and population coverage.

In addition to the usual measures of screening-test performance, it is important to consider testing frequency when evaluating a screening program. Data on which to base recommendations for the timing of screening tests are urgently needed. For example, in the cases of cervical and colon cancer, when the target is a precursor lesion, research indicates that less frequent screening may be appropriate. This finding may not apply, however, to screening for breast cancer by mammography, which requires currently recommended intervals for the early detection of malignancies. Resources now allocated to breast cancer might more effectively be applied to the construction of tests that would permit longer intervals between screenings. To achieve the National Cancer Institute's goal of reducing cancer mortality in the United States by the year 2000, it will be important to review the balance between population coverage and individual screening for each cancer and to emphasize prevention strategies that maximize population coverage while minimizing expenditures.

Adult↗
PubMed1996

Multiple-outcome meta-analysis of clinical trials.

When several clinical trials report multiple outcomes, meta-analyses ordinarily analyse each outcome separately. Instead, by applying generalized-least-squares (GLS) regression, Raudenbush et al. showed how to analyse the multiple outcomes jointly in a single model. A variant of their GLS approach, discussed here, can incorporate correlations among the outcomes within treatment groups and thus provide more accurate estimates. Also, it facilitates adjustment for covariates. In our approach, each study need not report all outcomes nor evaluate all treatments. For example, a meta-analysis may evaluate two or more treatments (one 'treatment' may be a control) and include all randomized controlled trials that report on any subset (of one or more) of the treatments of interest. The analysis omits other treatments that these trials evaluated but that are not of interest to the meta-analyst. In the proposed fixed-effects GLS regression model, study-level and treatment-arm-level covariates may be predictors of one or more of the outcomes. An analysis of rheumatoid arthritis data from trials of second-line drug treatments (used after initial standard therapies prove unsatisfactory for a patient) motivates and applies the method. Data from 44 randomized controlled trials were used to evaluate the effectiveness of injectable gold and auranofin on the three outcomes tender joint count, grip strength, and erythrocyte sedimentation rate. The covariates in the regression model were quality and duration of trial and baseline measures of the patients' disease severity and disease activity in each trial. The meta-analysis found that gold was significantly more effective than auranofin on all three treatment outcomes. For all estimated coefficients, the multiple-outcomes model produced moderate changes in their values and slightly smaller standard errors, to the three separate outcome models.

Antirheumatic Agents↗
PubMed1996

Uncertainty of the time of first significance in random effects cumulative meta-analysis.

We propose a process for evaluating quantities of clinical and statistical interest in cumulative meta-analysis. We use Monte Carlo simulation studies to assess the error variance of the time to significance in cumulative meta-analysis. For the specific cumulative meta-analyses that we simulated, the 95% confidence interval of the treatment effect, estimated by the random effects method at the time of earliest significance, appears to be approximately appropriate except when the hypothesized treatment effect is near the null. The Monte Carlo approach that we used can also estimate the power of a cumulative meta-analysis when two treatments differ in efficacy. We illustrate these issues in the context of five cumulative meta-analyses, each comparing two treatments for preventing mortality from myocardial infarction. These simulated meta-analyses demonstrate our main point, which is that the time of first significance, however parameterized, is itself a random variable with error variance.

Bias↗
PubMed1995

A random-effects regression model for meta-analysis.

Many meta-analyses use a random-effects model to account for heterogeneity among study results, beyond the variation associated with fixed effects. A random-effects regression approach for the synthesis of 2 x 2 tables allows the inclusion of covariates that may explain heterogeneity. A simulation study found that the random-effects regression method performs well in the context of a meta-analysis of the efficacy of a vaccine for the prevention of tuberculosis, where certain factors are thought to modify vaccine efficacy. A smoothed estimator of the within-study variances produced less bias in the estimated regression coefficients. The method provided very good power for detecting a non-zero intercept term (representing overall treatment efficacy) but low power for detecting a weak covariate in a meta-analysis of 10 studies. We illustrate the model by exploring the relationship between vaccine efficacy and one factor thought to modify efficacy. The model also applies to the meta-analysis of continuous outcomes when covariates are present.

BCG Vaccine↗
PubMed1995

Multiple-outcomes meta-analysis of treatments for periodontal disease.

The results of periodontal therapy vary by disease severity, outcome measure, and method of data analysis. Several clinical trials and a subsequent meta-analysis have demonstrated that, for teeth with severe disease, surgery decreases probing depth (PD) and increases attachment level (AL) more than non-surgical treatment. For other disease levels, the choice of therapy depends on the outcome measure. When clinical trials use two or more outcome measures (such as PD and AL), investigators ordinarily analyze each outcome separately. When the correlations are incorporated among the outcomes, a meta-analysis can use generalized-least-squares (GLS) regression to analyze multiple outcomes jointly. We applied the GLS multiple-outcomes model in a meta-analysis of 5 trials comparing surgical and non-surgical periodontal treatments, each assessing the outcomes PD and AL one year after treatment. The clinical conclusions are similar to those reported earlier, but our estimates of the relative benefits of surgical and non-surgical treatment should be more accurate, because the GLS method takes into account correlation between AL and PD. When correlations between the two outcomes rise, as they do with increasing severity of disease, the GLS estimates depart from those derived from separate analyses of PD and AL.

Dental Scaling↗
PubMed1995

The efficacy of bacillus Calmette-Guérin vaccination of newborns and infants in the prevention of tuberculosis: meta-analyses of the published literature.

OBJECTIVE: To quantify the efficacy of vaccination of infants with bacillus Calmette-Guérin (BCG) against tuberculosis. DATA SOURCES: MEDLINE with index terms BCG vaccine, tuberculosis, and human; lists of all known studies provided by experts at the Centers for Disease Control and Prevention, the World Health Organization, and other organizations. STUDY SELECTION: A total of 1264 articles and abstracts were reviewed for details on BCG vaccination, the availability of concurrent vaccinated and unvaccinated groups, and a tuberculosis outcome. Seventy articles were reviewed in depth for method of vaccine allocation used to create comparable groups, age at vaccination of study participants, comparability of surveillance and follow-up of recipient and concurrent control groups in trials, an appropriately defined control group in case-control studies, and outcome measures (tuberculosis cases and/or deaths). Five prospective trials and eleven case-control studies of vaccination during infancy were included in the present analyses. DATA EXTRACTION: We recorded study design, age range of study population, number of patients enrolled, efficacy of vaccine, location of the study, and a series of items to assess the potential for bias in study design, follow-up, and diagnosis. We extracted or computed vaccine efficacy by years since vaccination wherever possible. At least two readers independently extracted data and evaluated data validity. DATA SYNTHESIS: The relative risk (RR) or odds ratio (OR) for tuberculosis in vaccinated versus unvaccinated infants was the measure of vaccine efficacy analyzed. A random-effects method estimated a weighted average RR or OR from data extracted from the trials and case-control studies. The protective effect was then computed by 1-RR or 1-OR. Overall, the protective effect of vaccination against cases of tuberculosis was 0.74 (95% confidence interval [95% CI], 0.62 to 0.83) when estimated from four randomized controlled trials, and 0.52 (95% CI, 0.38 to 0.64) when estimated from nine case-control studies. Five trials reporting deaths from tuberculosis showed a BCG protective effect of 0.65 (95% CI, 0.12 to 0.86), five studies reporting on meningitis showed a protective effect of 0.64 (95% CI, 0.30 to 0.82), and three studies of disseminated tuberculosis showed a protective effect of 0.78 (95% CI, 0.58 to 0.88). Three case-control studies included separate results for laboratory-confirmed cases of tuberculosis. These studies documented a protective effect of 0.83 (95% CI, 0.58 to 0.93). In a random-effects regression model of the nine case-control studies, study validity score explained 15% of the heterogeneity among study-estimated protective effects, suggesting that better studies reported greater efficacy. Three trials and six case-control studies provided some age-specific information that allowed us to examine the duration of BCG efficacy. Most of this evidence suggested that BCG efficacy may persist through 10 years after infant vaccination. CONCLUSION: BCG vaccination of newborns and infants significantly reduces the risk of tuberculosis--by over 50%, on average. Protection has been observed across many populations, study designs, and forms of tuberculosis. Rates of protection against cases that are confirmed by laboratory tests, reflecting reduced error in disease classification and consequently more accurate estimates of BCG efficacy, are highest at 83%.

BCG Vaccine↗
PubMed1994

Efficacy of BCG vaccine in the prevention of tuberculosis. Meta-analysis of the published literature.

OBJECTIVE: To quantify the efficacy of BCG vaccine against tuberculosis (TB). DATA SOURCES: MEDLINE with index terms BCG vaccine, tuberculosis, and human. Experts from the Centers for Disease Control and Prevention and the World Health Organization, among others, provided lists of all known studies. STUDY SELECTION: A total of 1264 articles or abstracts were reviewed for details on BCG vaccination, concurrent vaccinated and unvaccinated groups, and TB outcome; 70 articles were reviewed in depth for method of vaccine allocation used to create comparable groups, equal surveillance and follow-up for recipient and concurrent control groups, and outcome measures of TB cases and/or deaths. Fourteen prospective trials and 12 case-control studies were included in the analysis. DATA EXTRACTION: We recorded study design, age range of study population, number of patients enrolled, efficacy of vaccine, and items to assess the potential for bias in study design and diagnosis. At least two readers independently extracted data and evaluated validity. DATA SYNTHESIS: The relative risk (RR) or odds ratio (OR) of TB provided the measure of vaccine efficacy that we analyzed. The protective effect was then computed by 1-RR or 1-OR. A random-effects model estimated a weighted average RR or OR from those provided by the trials or case-control studies. In the trials, the RR of TB was 0.49 (95% confidence interval [CI], 0.34 to 0.70) for vaccine recipients compared with nonrecipients (protective effect of 51%). In the case-control studies, the OR for TB was 0.50 (95% CI, 0.39 to 0.64), or a 50% protective effect. Seven trials reporting tuberculous deaths showed a protective effect from BCG vaccine of 71% (RR, 0.29; 95% CI, 0.16 to 0.53), and five studies reporting on meningitis showed a protective effect from BCG vaccine of 64% (OR, 0.36; 95% CI, 0.18 to 0.70). Geographic latitude of the study site and study validity score explained 66% of the heterogeneity among trials in a random-effects regression model. CONCLUSION: On average, BCG vaccine significantly reduces the risk of TB by 50%. Protection is observed across many populations, study designs, and forms of TB. Age at vaccination did not enhance predictiveness of BCG efficacy. Protection against tuberculous death, meningitis, and disseminated disease is higher than for total TB cases, although this result may reflect reduced error in disease classification rather than greater BCG efficacy.

BCG Vaccine↗
PubMed1994

Epidemiologic study of sound surface trends in a 10-year longitudinal study.

Longitudinal data of 589 men aged 30-65 yr, each followed for 10 yr, were analyzed to identify variables which may be associated with healthy tooth surface loss. A longitudinal linear growth curve model was used. As expected, older cohorts tended to have fewer sound surfaces (P < 0.02), but they also tended to have greater rates of sound surface loss (P < 0.01). Age, bone loss, number of teeth at baseline, gingivitis, pocket depth and calculus were individually correlated (P < 0.05) with the rate of sound surface loss. The number of filled or diseased surfaces at baseline was also marginally correlated (P < 0.06) with rate of sound surface loss.

Adult↗
PubMed1994

Efficacy and safety of nonsteroidal antiinflammatory drugs for cancer pain: a meta-analysis.

PURPOSE: To assess the efficacy and safety of nonsteroidal antiinflammatory drugs (NSAIDs) in the treatment of cancer pain by meta-analyses of the published randomized control trials (RCTs). PATIENTS AND METHODS: Twenty-five studies met inclusion criteria for analysis. Of these, 13 tested a single-dose effect, nine multiple-dose effects, and three both single- and multiple-dose effects of 16 different NSAIDs in a total of 1,545 patients. Baseline pain intensity (when provided) of moderate or higher was indicated in 81% of patients. RESULTS: Single-dose NSAID studies found greater analgesic efficacy than placebo, with rough equivalence to 5 to 10 mg of intramuscular morphine. Pain scores differed insignificantly for aspirin versus three other NSAIDs. Analgesic responses to low- and high-dose NSAIDs suggested a dose-response relationship, but this was not statistically significant. Recommended and supramaximal single doses of three NSAIDs produced comparable changes in pain scores, which indicates a ceiling analgesic effect. Common side effects included upper gastrointestinal symptoms, dizziness, and drowsiness. The incidence of side effects showed a trend to increase with dose, without a ceiling effect, and to increase with multiple doses. Single or multiple doses of weak opioids (WO) alone or in combination (WO/C) with nonopioid analgesics did not produce greater analgesia than NSAIDs alone. Single doses of WO/C analgesics produced more side effects than NSAIDs alone, although both side effect incidence and patient dropout rates were equal when multiple doses were administered. CONCLUSION: These findings question whether the traditional World Health Organization (WHO) second analgesic step (addition of a weak opioid when pain is inadequately treated by a nonopioid analgesic alone) is warranted. A lack of comparable studies precluded testing the hypothesis that NSAIDs are particularly effective for malignant bone pain.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1993

Cognitive behavioral techniques for hypertension: are they effective?

PURPOSE: To assess by analysis of published controlled trials the efficacy of cognitive behavioral therapies (such as biofeedback, relaxation, meditation) for essential hypertension. DATA IDENTIFICATION: Randomized controlled trials published in the English language between 1970 and 1991 identified from the MEDLINE database and bibliographic references from these articles. STUDY SELECTION: Limited to studies involving randomized assignment to a treatment group consisting of one or more cognitive behavioral interventions or a concurrent control group consisting of no therapy, a waiting list, regular monitoring, or placebo intervention. RESULTS OF DATA SYNTHESIS: Although we identified more than 800 published works, only 26 met entry criteria. We identified a number of methodologic short-comings, including small sample size, inconsistencies regarding baseline blood pressure determinations and types of control groups, and the possibility of confounding by multiple noncognitive cointerventions (diet, exercise) and expectancy (the placebo effect). In meta-analyses involving 1264 patients, differences in mean blood pressure reduction varied according to the duration of baseline blood pressure measurements and type of control groups studied. In 16 comparisons involving baseline periods of more than 1 day, with patients (n = 368) assigned to either a cognitive therapy or a placebo intervention (sham biofeedback, "pseudo-meditation"), systolic and diastolic blood pressures decreased by 2.8 mm Hg (95% CI, -0.8 to 6.4) and 1.3 mm Hg (CI, -1.3 to 3.8), respectively. These changes were neither statistically nor clinically significant. CONCLUSION: Cognitive interventions for essential hypertension are superior to no therapy but not superior to credible sham techniques or to self-monitoring alone. The literature on this subject is limited by a variety of methodologic inadequacies. No single cognitive behavioral technique appears to be more effective than any other.

Behavior Therapy↗
PubMed1993

Longitudinal height velocity standards for U.S. adolescents.

Longitudinally based height velocity centiles for U.S. children, appropriate for paediatric clinical use, were derived for growth from ages 7 to 18 years. A series of gender- and race-specific figures present the median velocity curves for children by year of maturation. Smooth 3rd to 97th centile curves, for blacks and whites together, are provided for children who are early, average, and late maturers. The data were taken from 6532 black and white children participating in the Six Cities Study from 1974 to 1989.

Adolescent↗
PubMed1993

Predictors of human gestational length.

OBJECTIVES: Our objective was to identify statistically significant variables that determine the length of human gestation. STUDY DESIGN: Multiple linear regression was used to analyze 9355 observations from the Delivery Interview Program, a cross-sectional study conducted from 1977 through 1980 at the Boston Hospital for Women (now called the Brigham and Women's Hospital). RESULTS: Maternal parity, age, and race were found to be the most important variables determining the length of human gestation. Multiparous women, women aged < 19 or > 34 years, and black women were found to have shorter gestations than primiparous women, women aged 19 to 34 years, or white women. CONCLUSION: By means of our linear model the length of pregnancy for women with different risk factors can be estimated more precisely than Naegele's rule allows.

Adult↗
PubMed1993

Longitudinal statistical models for loss of sound surfaces.

Longitudinal data of 50-yr-old men, followed for 10 yr, were analyzed to identify variables which may be associated with healthy tooth surface loss. Three types of longitudinal models were used, arriving at similar conclusions. Predictors of sound tooth surface loss with aging included pocket depth, mobility, and recession.

Aging↗
PubMed1991

Long-term memory of body weight and past weight satisfaction: a longitudinal follow-up study.

Recalled body weight and self-reported current weight were validated in a longitudinal study population by comparing recalls at 50 y to actual measures taken at ages 18, 30, 40, and 50 y. Recalled body weights were also compared with reported desired weights at these same ages. Self-reported weights at 50 y were equally accurate for both males and females; the mean reporting underestimate was -1.98 kg for males and -1.86 kg for females. Males' self reports at age 50 y were influenced by years of education (P less than 0.005) and current body size (P less than 0.0001) whereas females' were not. Correlations between recall of past weights and measured weights ranged from r = 0.87 at 18 y to 0.95 at 40 y. Recalls of past body weight were not significantly influenced by the passage of time, the number of years of education, or the accuracy of current weight reports. Current body size (wt/ht2) was significantly associated with life-time weight dissatisfaction in both sexes (P less than 0.0005).

Body Image↗