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Michael S Kramer

Publications and source records attributed to Michael S Kramer.

At least 37 records · Page 2Linked to original sources
PubMed2005

The early natural history of nephropathy in Type 1 Diabetes: III. Predictors of 5-year urinary albumin excretion rate patterns in initially normoalbuminuric patients.

Predictors of albumin excretion rate (AER) abnormalities could provide earlier indicators of diabetic nephropathy risk. Data from the Natural History Study, a prospective 5-year observation of renal structure and function in young type 1 diabetic patients, were examined for predictors of AER patterns in normoalbuminuric type 1 diabetic patients. Included were 170 patients (96 females) (aged 16.7 +/- 5.9 years, duration of diabetes 8.0 +/- 4.3 years) with normal blood pressure, normoalbuminuria (AER <20 microg/min), and eight or more follow-up visits over 5 years. AER, blood pressure, and HbA1c (A1C) were determined quarterly and glomerular filtration rate (GFR) annually. Persistent microalbuminuria (PMA) was defined as 20-200 microg/min in two of three consecutive values within 6-12 months. Four different AER patterns were identified. Group 1 (n = 99): all values <20 microg/min. Group 2 (n = 49): intermittent levels >20 microg/min but not meeting microalbuminuria criteria. Group 3 (n = 14): PMA during follow-up but normoalbuminuria at study exit. Group 4 (n = 8): microalbuminuria at study exit. Group 4 (497 +/- 95 nm, P < 0.01) and group 3 (464 +/- 113 nm, P = 0.03) patients had greater baseline glomerular basement membrane (GBM) width versus group 1 (418 +/- 67 nm). Baseline GFR in group 4 (163 +/- 37 ml.min(-1). 1.73 m(-2)) was higher than group 1 (143 +/- 28 ml.min(-1) . 1.73 m(-2), P = 0.04). A1C was higher in group 2 (9.0 +/- 1.2%) than group 1 (8.4 +/- 1.1%, P = 0.008). Thus, greater increases in GBM width and GFR were predictors of PMA. Since 64% of the patients that developed microalbuminuria reverted to normoalbuminuria, the risk of diabetic nephropathy as defined by current microalbuminuria criteria is unclear.

Adolescent↗
PubMed2004

Infant mortality among First Nations versus non-First Nations in British Columbia: temporal trends in rural versus urban areas, 1981-2000.

BACKGROUND: Increasingly more First Nations (FN) people have moved from rural to urban areas. It is unknown how disparities in infant mortality among FN versus non-FN women have changed over time in urban versus rural areas. METHODS: We conducted a birth cohort-based study of all 877 925 live births (56 771 FN and 821 154 non-FN) registered in British Columbia, 1981-2000. Main outcomes included rates, risk differences, and relative risks of neonatal, postneonatal, and overall infant death. RESULTS: Both neonatal and postneonatal mortality rates for FN infants showed a steady decline in rural areas but a rise-and-fall pattern in urban areas. Relative risks for overall infant death among FN versus non-FN infants declined steadily from 2.75 (95% CI: 2.04, 3.72) to 1.87 (95% CI: 1.24, 2.81) in rural areas from 1981-1984 to 1997-2000, but rose from 1.59 (95% CI: 1.27, 1.99) (1981-1984) to 2.80 (2.33-3.37) (1989-92) and then fell to 1.89 (1.44-2.49) (1997-2000) in urban areas. Risk differences for neonatal death among FN versus non-FN infants declined substantially over time in rural but not urban areas. The disparities in neonatal death among FN versus non-FN were largely explained by differences in preterm birth, while the disparities in postneonatal death were not explained by observed maternal and pregnancy characteristics. CONCLUSIONS: Reductions in disparities in infant mortality among FN versus non-FN women have been less substantial and consistent over time in urban versus rural areas of British Columbia, suggesting the need for greater attention to FN maternal and infant health in urban areas.

Adult↗
PubMed2004

A proportional hazards model with time-dependent covariates and time-varying effects for analysis of fetal and infant death.

Birth-weight- and gestational-age-specific perinatal mortality curves intersect when compared by race and maternal smoking. The authors propose a new measure to replace fetal and infant mortality and an analytic strategy to assess the effects of risk factors on this outcome. They used 1998 data for US Blacks and Whites. Age-specific post-last menstrual period (LMP) mortality rate was defined as the proportion of deaths (stillbirth, perinatal death, or infant death) at a given age post-LMP. The authors used extended Cox regression with time-varying covariates and hazard ratios to model the effects of race and smoking on post-LMP mortality. Perinatal mortality rates (conventional calculation) for Blacks and Whites showed the expected crossover. However, analyses of post-LMP mortality showed no crossover. For the Black-White comparison, a hazard ratio of 1.72 (95% confidence interval: 1.67, 1.77) was obtained. The hazard was higher for smokers than for nonsmokers, but the hazard ratio increased from 1.09 (95% confidence interval: 0.98, 1.22) at 22 weeks to 1.82 (95% confidence interval: 1.72, 1.92) at 40 weeks. The hazard ratio associated with birth was also time dependent: higher than 1 for preterm gestation and lower than 1 for term gestation. The increasing adverse effect of smoking with gestational age suggests an accumulating effect of smoking on mortality. Modeling post-LMP mortality eliminates the crossover paradox for race and maternal smoking in a single statistical model.

Birth Weight↗
PubMed2004

Analysis of neonatal mortality:is standardizing for relative birth weight biased?

BACKGROUND: Infant mortality has traditionally been analyzed as a function of birth weight and birth weight-specific mortality. Often, however, when comparing two populations, the population with higher overall mortality has lower mortality at low birth weights and a reversed pattern at higher birth weights. Methods standardizing birth weight, such as the "relative birth weight", have been proposed to eliminate these crossover effects, but such methods do not account for the separate contributions to birth weight of gestational age and fetal "growth." METHODS: Using data for singleton U.S. Blacks (n = 3,683,572) and Whites (n = 18,409,287), we compared neonatal mortality, gestational age, and the difference between the observed birth weight and the optimal birth weight (the weight at which neonatal mortality was lowest) among Black and White infants at the same relative birth weight. RESULTS: At relative birth weights below zero, gestational ages were, on average, 2.4 +/- 1.5 (mean +/- standard deviation) weeks shorter for Blacks than for Whites for the same relative birth weight. At relative birth weights above zero, no differences were observed in gestational age, but the optimal birth weight occurred at a much higher relative birth weight in Whites than in Blacks (4150 vs. 3550 g). CONCLUSIONS: Our results suggest that comparisons of neonatal mortality between groups using "relative" birth weight may be potentially biased by differences in gestational age at low birth weights, and by the distance from the optimal birth weight at higher birth weights.

Journal Article↗
PubMed2004

A parsimonious explanation for intersecting perinatal mortality curves: understanding the effects of race and of maternal smoking.

BACKGROUND: Neonatal mortality rates among black infants are lower than neonatal mortality rates among white infants at birth weights <3000 g, whereas white infants have a survival advantage at higher birth weights. This finding is also observed when birth weight-specific neonatal mortality rates are compared between infants of smokers and non-smokers. We provide a parsimonious explanation for this paradoxical phenomenon. METHODS: We used data on births in the United States in 1997 after excluding those with a birth weight <500 g or a gestational age <22 weeks. Birth weight- and gestational age-specific perinatal mortality rates were calculated per convention (using total live births at each birth weight/gestational age as the denominator) and also using the fetuses at risk of death at each gestational age. RESULTS: Perinatal mortality rates (calculated per convention) were lower among blacks than whites at lower birth weights and at preterm gestational ages, while blacks had higher mortality rates at higher birth weights and later gestational ages. With the fetuses-at-risk approach, mortality curves did not intersect; blacks had higher mortality rates at all gestational ages. Increases in birth rates and (especially) growth-restriction rates presaged gestational age-dependent increases in perinatal mortality. Similar findings were obtained in comparisons of smokers versus nonsmokers. CONCLUSIONS: Formulating perinatal risk based on the fetuses-at-risk approach solves the intersecting perinatal mortality curves paradox; blacks have higher perinatal mortality rates than whites and smokers have higher perinatal mortality rates than nonsmokers at all gestational ages and birth weights.

Journal Article↗
PubMed2004

Risks of stillbirth and early neonatal death by day of week.

BACKGROUND: Higher risks of stillbirth or early neonatal death, or both, have been reported from several countries for births on weekend days. It is unclear whether such higher risks have persisted in recent years. We investigated weekend-associated risks of stillbirth and early neonatal death in most Canadian provinces. METHODS: We studied all 3 239 972 births recorded in Canada, excluding Ontario, between 1985 and 1998. The main outcome measures were the relative risks (RRs) of stillbirth and early neonatal death for infants born on weekends versus weekdays. RESULTS: The proportion of births on weekend days was 24% lower than the proportion on weekdays. Infants born on weekend days had slightly but significantly elevated risks of stillbirth (RR 1.06, 95% confidence interval [CI] 1.02-1.09) and early neonatal death (RR 1.11, 95% CI 1.07-1.16). However, the higher risks disappeared after adjustment for gestational age. INTERPRETATION: The crude risks of stillbirth and early neonatal death remained slightly higher for births on weekend days, but the excesses were much smaller than those reported from other countries.

Asphyxia Neonatorum↗
PubMed2004

The optimal duration of exclusive breastfeeding: a systematic review.

Although the health benefits of breastfeeding are acknowledged widely, opinions and recommendations are divided on the optimal duration of exclusive breastfeeding. We systematically reviewed available evidence concerning the effects on child health, growth, and development and on maternal health of exclusive breastfeeding for 6 months vs. exclusive breastfeeding for 3-4 months followed by mixed breastfeeding (introduction of complementary liquid or solid foods with continued breastfeeding) to 6 months. Two independent literature searches were conducted, together comprising the following databases: MEDLINE (as of 1966), Index Medicus (prior to 1966), CINAHL, HealthSTAR, BIOSIS, CAB Abstracts, EMBASE-Medicine, EMBASE-Psychology, Econlit, Index Medicus for the WHO Eastern Mediterranean Region, African Index Medicus, Lilacs (Latin American and Carribean literature), EBM Reviews-Best Evidence, the Cochrane Database of Systematic Reviews, and the Cochrane Controlled Trials Register. No language restrictions were imposed. The two searches yielded a total of 2,668 unique citations. Contacts with experts in the field yielded additional published and unpublished studies. Studies were stratified according to study design (controlled trials vs. observational studies) and provenance (developing vs. developed countries). The main outcome measures were weight and length gain, weight-for-age and length-for-age z-scores, head circumference, iron status, gastrointestinal and respiratory infectious morbidity, atopic eczema, asthma, neuromotor development, duration of lactational amenorrhea, and maternal postpartum weight loss. Twenty independent studies meeting the selection criteria were identified by the literature search: 9 from developing countries (2 of which were controlled trials in Honduras) and 11 from developed countries (all observational studies). Neither the trials nor the observational studies suggest that infants who continue to be exclusively breastfed for 6 months show deficits in weight or length gain, although larger sample sizes would be required to rule out modest increases in the risk of undernutrition. The data are conflicting with respect to iron status but suggest that, at least in developing-country settings, where iron stores of newborn infants may be suboptimal, exclusive breastfeeding without iron supplementation through 6 months of age may compromise hematologic status. Based primarily on an observational analysis of a large randomized trial in Belarus, infants who continue exclusive breastfeeding for 6 months or more appear to have a significantly reduced risk of one or more episodes of gastrointestinal tract infection. No significant reduction in risk of atopic eczema, asthma, or other atopic outcomes has been demonstrated in studies from Finland, Australia, and Belarus. Data from the two Honduran trials suggest that exclusive breastfeeding through 6 months of age is associated with delayed resumption of menses and more rapid postpartum weight loss in the mother. Infants who are breastfed exclusively for 6 months experience less morbidity from gastrointestinal tract infection than infants who were mixed breastfed as of 3 or 4 months of age. No deficits have been demonstrated in growth among infants from either developing or developed countries who are exclusively breastfed for 6 months or longer. Moreover, the mothers of such infants have more prolonged lactational amenorrhea and faster postpartum weight loss. Based on the results of this review, the World Health Assembly adopted a resolution to recommend exclusive breastfeeding for 6 months to its member countries. Large randomized trials are recommended in both developed and developing countries to ensure that exclusive breastfeeding for 6 months does not increase the risk of undernutrition (growth faltering), to confirm the health benefits reported thus far, and to investigate other potential effects on health and development, especially over the long term.

Breast Feeding↗
PubMed2004

Comparison of maternal mortality and morbidity between trial of labor and elective cesarean section among women with previous cesarean delivery.

OBJECTIVE: This study was undertaken to assess the safety of trial of labor after previous cesarean delivery. STUDY DESIGN: Retrospective cohort study of 308,755 Canadian women with previous cesarean delivery between 1988 and 2000. Occurrences of in-hospital maternal death, uterine rupture, and other severe maternal morbidity were compared between women with a trial of labor and those with an elective cesarean section. RESULTS: Rates of uterine rupture (0.65%), transfusion (0.19%), and hysterectomy (0.10%) were significantly higher in the trial-of-labor group. Maternal in-hospital death rate, however, was lower in the trial-of-labor group (1.6 per 100,000) than in the elective cesarean section group (5.6 per 100,000). The association between trial of labor and uterine rupture was stronger in low volume (<500) than in high volume (> or =500 births per year) obstetric units. CONCLUSION: Trial of labor is associated with increased risk of uterine rupture, but elective cesarean section may increase the risk of maternal death.

Blood Transfusion↗
PubMed2004

Feeding effects on growth during infancy.

OBJECTIVE: To examine the effects of formula, other milks, other liquids, cereals, and other solid foods on growth during infancy. STUDY DESIGN: Observational cohort study nested within a large (n=17,046), cluster-randomized trial. We compared growth [weight-for-age, length-for-age, and weight-for-length z scores (WAZ, LAZ, WLZ) and head circumference (HC)] during the intervals 1 to 3, 3 to 6, 6 to 9, and 9 to 12 months, using hierarchical multivariate regression to control for size at the beginning of each interval, maternal education, geographic region, and urban versus rural location. RESULTS: Mixed BF and formula/other milk were associated with significantly higher (versus breast milk only) LAZ at 1 to 3 months (+0.038 and +0.047, respectively). In the 3- to 6-month interval, mixed BF and formula/other milk led to significantly higher WAZ (+0.125 and +0.139) and LAZ (+0.081 and +0.075), whereas cereal intake was associated with large and highly significant reductions in both measures (-0.293 and -0.240) and in HC (-0.291 cm). Mixed BF and formula/other milk continued to have positive albeit smaller associations with WAZ and LAZ in the 6- to 9-month and 9- to 12-month intervals. CONCLUSIONS: Our results confirm the growth-accelerating effects of formula and other milks (versus breast milk) on weight and length gain throughout infancy, with a dose-response gradient and largest associations observed at 3 to 6 months.

Body Height↗
PubMed2004

Recent trends in caesarean delivery rates and indications for caesarean delivery in Canada.

OBJECTIVE: To examine recent trends in Caesarean delivery rates as well as the indications for Caesarean delivery in Canada, excluding the provinces of Manitoba and Quebec. METHODS: All deliveries (N = 1 807 388) recorded in the Canadian Institute for Health Information's Discharge Abstract Database for the years 1994/95 to 2000/01 were included in the study (all hospital deliveries in Canada except for those occurring in Manitoba and Quebec). Temporal trends and inter-provincial/territorial variations in Caesarean delivery rates were quantified, and the primary indications for Caesarean delivery during the study period were compared. RESULTS: The overall Caesarean delivery rate increased from 18.0% in 1994/95 to 22.1% in 2000/01. The primary Caesarean delivery rate increased from 12.7% to 16.3%, while the rate of vaginal birth after Caesarean decreased from 33.3% to 28.5% over the same period. Most of the increase in primary Caesarean deliveries was due to increases in Caesarean deliveries for dystocia, which increased from 6.9% in 1994/95 to 9.2% in 2000/01. The largest increase in repeat Caesarean deliveries was due to elective repeat Caesarean sections, which increased from 37.7% to 40.3%. Approximately 15% of the increase in overall Caesarean delivery rates was explained by increases in maternal age. The rate of vaginal deliveries following forceps rotation declined from 1.9% in 1994/95 to 1.3% in 2000/01. CONCLUSION: Most of the recent increase in Caesarean delivery rates in Canada was attributed to increases in primary Caesarean delivery for dystocia and elective repeat Caesarean deliveries.

Adult↗
PubMed2004

Determinants of intrapartum fetal death in a remote and indigent population in China.

OBJECTIVE: To explore the reasons for the high rate of intrapartum fetal death observed in a remote and indigent population in China. STUDY DESIGN: We conducted an epidemiologic analysis of determinants of intrapartum fetal death in a sample of 20,891 births in 18 hospitals participating in the Qingyuan Perinatal Surveillance System from January 1, 1997 to June 30, 1998. The main determinant examined was cesarean delivery; other determinants included mother's insurance status, residence, maternal age, infant's gender, parity, gestational age, birth weight, and obstetric complications. Rates of intrapartum fetal death within categories of various maternal and infant factors were first calculated and compared; adjusted odds ratios for intrapartum fetal death were then estimated by multiple logistic regression analysis. RESULTS: The intrapartum fetal death rate in this population was 5 per 1000 total births, which accounted for about one-third of all fetal deaths. Compared with vaginal delivery, elective cesarean delivery was associated with a 100% (i.e., no intrapartum fetal death among 1572 elective cesarean deliveries) and emergency cesarean delivery with a 88% reduction, in intrapartum fetal death. Other significant determinants were related to access to obstetric care (i.e., insurance status and residence). CONCLUSION: Lack of access to quality obstetric care is the major determinant of intrapartum fetal death in this population.

Adult↗
PubMed2004

Disparities in pregnancy outcomes according to marital and cohabitation status.

OBJECTIVE: To assess the risks and trends of adverse pregnancy outcomes among mothers in common-law unions versus traditional marriage relationships. METHODS: We conducted a birth cohort-based study of all 720,586 births registered in Quebec for the years 1990 to 1997. RESULTS: The proportion of births to common-law mothers more than doubled from 20% in 1990 to 44% in 1997. Preterm birth, low birth weight, small for gestational age, and neonatal and postneonatal mortality rates increased progressively from mothers legally married, to common-law unions, to lone mothers with father information, to lone mothers without father information on birth registrations. Adjusted odd ratios with 95% confidence intervals (CIs) for common-law versus legally married mothers were 1.14 (95% CI 1.11, 1.17) for preterm birth, 1.21 (95% CI 1.18, 1.25) for low birth weight, 1.18 (95% CI 1.16, 1.20) for small for gestational age, 1.07 (95% 0.97, 1.19) for neonatal death, and 1.23 (95% CI 1.04, 1.44) for postneonatal death after controlled for observed individual- and community-level characteristics. The crude and adjusted odds ratios were virtually unchanged over time. CONCLUSION: Pregnancy outcomes are worse among mothers in common-law unions versus traditional marriage relationships but better than among mothers living alone. Modest disparities in pregnancy outcomes in common-law versus traditional marriage relationships have persisted despite the striking rise in common-law unions. LEVEL OF EVIDENCE: II-2

Birth Weight↗
PubMed2004

Disparities in birth outcomes by neighborhood income: temporal trends in rural and urban areas, british columbia.

BACKGROUND: Knowledge of socioeconomic disparities in health is of interest to both the general public and public health policymakers. It is unclear how disparities in birth outcomes by socioeconomic status have changed over time, particularly in settings with universal health insurance and favorable socioeconomic conditions. METHODS: We identified a cohort of all births (n = 713,950) registered in British Columbia, 1985-2000. We compared rates and relative risks (RRs) of preterm birth, small-for-gestational-age (SGA), stillbirth, and neonatal and postneonatal death across neighborhood-income quintiles from Q1 (richest, the reference) to Q5 (poorest) by 4-year intervals in rural and urban areas. Logistic regression was used to control for maternal and pregnancy characteristics. RESULTS: Maternal characteristics varied widely across neighborhood-income quintiles in both rural and urban areas. There were moderate and persistent disparities in birth outcomes across neighborhood-income quintiles in urban but not rural areas. The relative disparities in urban areas did not diminish over time for all birth outcomes and actually rose for postneonatal mortality. For example, crude RRs (95% confidence intervals) for Q5 versus Q1 in urban areas for SGA were 1.44 (1.37-1.52) in 1985-1988 and 1.41 (1.33-1.49) in 1997-2000; for postneonatal death, the corresponding results were 1.61 (1.17-2.20) and 2.20 (1.24-3.92), respectively. Most of the observed disparities could not be explained by observed maternal and pregnancy characteristics. CONCLUSION: Moderate disparities in birth outcomes by neighborhood income persist in urban areas (although not rural areas) of British Columbia, despite a universal health insurance system and generally favorable socioeconomic conditions.

British Columbia↗
PubMed2004

Risks of adverse pregnancy outcomes among Inuit and North American Indian women in Quebec, 1985-97.

We used Statistics Canada's linked stillbirth, live birth and infant death files to assess the risks of adverse pregnancy outcomes among Inuit and North American Indian vs. other ethnic women in Quebec, 1985-97 (1 125 462 singleton births). Mother tongue was used to define ethnicity, with the largest French language group as the reference. Main outcome measures are adjusted odds ratios (AOR) for preterm birth, small-for-gestational-age (SGA), stillbirth, neonatal and postneonatal death controlled for maternal age, education, marital status, parity, infant sex, community size, and community-level random effects using multilevel logit models. Inuit women had higher risks of preterm birth (AOR = 1.49, 95% CI [1.25, 1.78]) and immaturity-related infant mortality (AOR = 3.03 [1.36, 6.74]), while Indian women did not. Infants of Inuit (AOR = 0.39 [0.31, 0.49]) and Indian (AOR = 0.27 [0.24, 0.31]) women had substantially lower risks of SGA. Elevated risks of stillbirth were observed among Indian women [AOR = 1.53 (1.09, 2.15)], and of postneonatal death among both Inuit (AOR = 4.45 [2.74, 7.22]) and Indian (AOR = 1.86 [1.28, 2.70]) infants. Both Inuit and Indian infants had much higher risks of sudden infant death syndrome (SIDS) and infection-related mortality. Although the absolute risks of adverse outcomes declined from 1985-87 to 1995-97, the relative disparities between aboriginal and non-aboriginal women changed little over this period. We conclude that Inuit and Indian women have different risk profiles for adverse pregnancy outcomes, and that prevention of preterm birth among Inuit women, and of SIDS and infection-related infant mortality in both aboriginal groups, are important targets for future research and intervention.

Adult↗
PubMed2004

Sudden infant death syndrome in Canada: trends in rates and risk factors, 1985-1998.

In Canada, sudden infant death syndrome (SIDS) remains the leading cause of postneonatal death. However, SIDS rates have been declining in many countries, including Canada. This decline has been largely attributed to recommendations to avoid placing infants to sleep in the prone position. We examined the postneonatal rate of mortality due to SIDS and to other causes in relation to the initial risk reduction campaign. The postneonatal mortality rate due to SIDS decreased from 0.97 to 0.54 per 1,000 neonatal survivors between 1985-1989 and 1994-1998 (relative risk [RR] = 0.56, 95% confidence interval [CI] 0.51-0.62). The rate of postneonatal mortality due to other causes also decreased during the same period, though to a smaller extent, from 1.19 to 0.86 (RR = 0.72, 95% CI 0.66-0.78). With the exception of seasonality, established risk factors for SIDS remained essentially unchanged between the two time periods. The observed reduction in postneonatal SIDS is consistent with a positive impact of the initial recommendations regarding risk reduction. However, the lack of reliable risk factor data limits the extent to which the decline can be attributed directly to the campaign.

Birth Weight↗
PubMed2003

A parsimonious explanation for intersecting perinatal mortality curves: understanding the effect of plurality and of parity.

BACKGROUND: Birth weight- and gestational age-specific perinatal mortality curves intersect when compared across categories of maternal smoking, plurality, race and other factors. No simple explanation exists for this paradoxical observation. METHODS: We used data on all live births, stillbirths and infant deaths in Canada (1991-1997) to compare perinatal mortality rates among singleton and twin births, and among singleton births to nulliparous and parous women. Birth weight- and gestational age-specific perinatal mortality rates were first calculated by dividing the number of perinatal deaths at any given birth weight or gestational age by the number of total births at that birth weight or gestational age (conventional calculation). Gestational age-specific perinatal mortality rates were also calculated using the number of fetuses at risk of perinatal death at any given gestational age. RESULTS: Conventional perinatal mortality rates among twin births were lower than those among singletons at lower birth weights and earlier gestation ages, while the reverse was true at higher birth weights and later gestational ages. When perinatal mortality rates were based on fetuses at risk, however, twin births had consistently higher mortality rates than singletons at all gestational ages. A similar pattern emerged in contrasts of gestational age-specific perinatal mortality among singleton births to nulliparous and parous women. Increases in gestational age-specific rates of growth-restriction with advancing gestational age presaged rising rates of gestational age-specific perinatal mortality in both contrasts. CONCLUSIONS: The proper conceptualization of perinatal risk eliminates the mortality crossover paradox and provides new insights into perinatal health issues.

Journal Article↗
PubMed2003

Randomized trials and public health interventions: time to end the scientific double standard.

Randomized controlled trials have become the acceptedstandard for testing the efficacy and safety of clinical treatments but are rarely used in evaluating public health interventions. This article reviews the types of interventions and outcomes for which randomized trials are necessary to provide a scientifically rigorous evaluation. It also presents the results from two trials analyzed both experimentally and observationally to illustrate why observational studies can yield highly biased findings. This article provides a brief historical account of controlled human experiments, which reveals a surprising earlier tradition of rigorous experimental studies in the social sciences. After contrasting that tradition with the status quo, this article concludes with a plea to reject the double scientific standard of what constitutes acceptable evidence of efficacy for clinical versus public health interventions.

Evidence-Based Medicine↗