Biomedical subjects

Michael S Kramer

Publications and source records attributed to Michael S Kramer.

59 records · Page 4Linked to original sources

PubMed2002

ACE-I and ARBs in early diabetic nephropathy.

INTRODUCTION: Antihypertensive treatment of patients with clinical manifestations of diabetic nephropathy, and especially, renin-angiotensin system (RAS) inhibition, slows, but may not fully arrest progression towards end-stage renal disease. Studies using hard endpoints such as doubling of serum creatinine, dialysis, or death that are initiated before emergence of any renal functional abnormalities in diabetes, would be of impractical length and size. We therefore undertook a primary prevention study (The Renin-Angiotensin System Study or RASS) to determine if inhibition of the RAS could slow the development of a key diabetic glomerulopathy structural endpoint, increase in mesangial fractional volume (Vv[Mes/glom]). METHODS: This is a parallel group, double-blind, placebo-controlled trial with 285 patients with Type 1 diabetes mellitus (95 per group) randomised to receive the angiotensin-converting enzyme inhibitor, enalapril, the angiotensin II receptor blocker, losartan, or placebo. All patients are normotensive, normoalbuminuric and have normal or increased glomerular filtration rates at study entry. The study is based on primary endpoint of change in Vv(Mes/glom) from baseline to the five-year renal biopsy, with baseline and interval measures of albumin excretion rate, glomerular filtration rate, blood pressure, and glycaemia. Baseline, mid-point, and five-year retinal fundus photography are also performed. RESULTS: One thousand and sixty-five patients were interviewed, 707 refused participation and 73 were excluded. The target of 285 subjects were randomised and their clinical and demographic characteristics are described. Biopsy complications occurred in 17 (6%), only one of which required hospitalisation. There were no permanent biopsy-related sequelae. CONCLUSIONS: Renal structural variables are reasonable surrogate endpoints for studies of progression of early diabetic nephropathy. Although requiring substantial recruitment effort, diabetic nephropathy primary prevention trials based on change in renal structure are feasible.

Adult↗

PubMed2002

Under-reporting of maternal mortality in Canada: a question of definition.

In Canada, maternal mortality reporting is based on information contained on death certificates. To examine the extent to which maternal deaths are under-reported in Canada and whether this is likely to change under the 10th revision of the International Classification of Diseases (ICD), we linked live birth and stillbirth registrations to In Canada death registrations of women aged 10 to 50 for 1988 through 1992. We reviewed the death certificates of women found to have died while pregnant or within a year of the termination of pregnancy. The officially reported maternal mortality ratio for the study years was 3.7 deaths per 100,000 live births. Depending on whether we included deaths not certified as maternal deaths at the time the deaths occurred, revised ratios under ICD-9 ranged from 4.9 to 5.1 per 100,000 live births for deaths from direct obstetric causes and from 0.5 to 1.2 per 100,000 live births for deaths from indirect obstetric causes. Reflecting changes in classification criteria, revised ratios under ICD-10 were lower than those under ICD-9 for deaths from direct obstetric causes - ranging from 3.9 to 4.1 per 100,000 live births - and higher for deaths from indirect obstetric causes ranging from 2.0 to 3.0 per 100,000 live births. Of deaths from direct obstetric causes, those from cerebrovascular disease were the most numerous and also the most likely to be underreported. Deaths from pulmonary embolism and indirect obstetric causes were the next most likely to be underreported. In a companion article we report an investigation of whether deaths from causes not directly related to pregnancy -such as injury, infectious disease and epilepsy - are more or less likely to occur among pregnant and recently pregnant women.

Canada↗

PubMed2002

Cause-specific mortality during and after pregnancy and the definition of maternal death.

As part of a study to determine whether maternal mortality in Canada is under- reported, we explored the validity of including deaths not directly related to pregnancy. We linked live birth and stillbirth registrations to death registrations of women of reproductive age from 1988 through 1992. We calculated standardized mortality ratios, by cause, from deaths in women known to have been pregnant and deaths in same-aged women not known to have been pregnant within the same time period. Women known to have been pregnant were approximately half as likely to die as would be expected in each of two six-month time periods: from 20 weeks gestation to 42 days postpartum (SMR 0.4, 95% CI 0.3-0.5), and from 42 days to 225 days postpartum (SMR 0.5, 95% CI 0.5-0.6). Furthermore, pregnant and recently pregnant women were not more likely to die from specific causes, with the exception of diseases of the arteries, arterioles, and capillaries (SMR 3.5, 95% CI 1.3-7.7) during pregnancy or within 42 days of pregnancy termination. The only other SMR that was > 1 was for death from cerebrovascular disorders during pregnancy and up to 42 days postpartum, although not significantly so (SMR 1.4, 95% CI 0.8-2.2). No other cause-specific SMRs were > 1. Moreover, recently pregnant women were found to be much less likely to commit suicide or to be the victims of homicide. We found no empirical justification for including deaths not directly related to pregnancy in reported counts of maternal deaths for most of the causal categories we considered.

Canada↗

PubMed2002

The impact of missing birth weight in deceased versus surviving fetuses and infants in the comparison of birth weight-specific feto-infant mortality.

Birth weight-specific is preferred to crude feto-infant mortality in epidemiologic studies comparing rates across jurisdictions, because it can help limit the bias arising from regional differences in the completeness of reporting of vital events and in classification of live versus stillbirth among extremely small and immature infants. The potential impact of missing birth weight information in deceased versus surviving fetuses and infants in the comparison of birth weight-specific feto-infant mortality has been seldom examined, however. The authors investigated this issue, using data collected from two nationwide surveys of all pregnancy outcomes occurring 15 17 May 1989 and 12 16 February 1996, respectively, in Taiwan and the 1989 and 1996 linked birth and infant death records in Canada (excluding Ontario and Newfoundland). The proportions with missing birth weight information in Taiwan in 1989 were 25.0%, 15.4%, 0%, and 0.6%, respectively, for stillbirths, neonatal deaths, post-neonatal deaths, and survivors, and in 1996 were 100%, 5.0%, 0%, and 0.2%. The proportions with missing birth weight information in Canada in 1989 were 5.8%, 2.6%, 1.2%, and 0.6%, respectively, for fetal deaths, neonatal deaths, post-neonatal deaths, and survivors, and in 1996 were 5.0%, 2.4%, 1.1%, and 0.6%. Infant and (especially) fetal death rates were substantially higher in Taiwan than in Canada among births with missing birth weight. The authors concluded that differences in missing birth weight information between deaths and survivors can bias comparisons of birth weight-specific feto-infant mortality.

Bias↗

PubMedDate not supplied

Case-control confusion.

OBJECTIVE: Critical analysis of journal articles by using principles of evidence-based medicine is important for clinicians applying research results in their practice and is a valuable component of pediatric residency training. Appraisal of an article's methodological rigor is often tailored to a particular type of study design, so that misclassification of study design can confuse the appraisal. The goal of this study was to determine how often pediatric research articles that are self-declared as case-control studies conform to a standard definition for this study design. METHODS: A Medline search identified articles published in two pediatric journals from January 1996 through August 2004 with the phrase "case-control study" in the title or abstract. Articles that were self-declared as case-control studies were analyzed to determine whether they satisfied a standard definition of a case-control study. RESULTS: Of the 91 purported case-control studies, only 68 (75%) met the standard definition for at least the most important analysis. The remaining 23 articles could be classified as cross-sectional studies (N = 16) or prospective cohort studies (N = 7). CONCLUSIONS: Ambiguity in the definition of a case-control study can cause confusion in the critical appraisal of published clinical research.

Adolescent↗