P. McGee

Fall in C-Peptide During First 2 Years From Diagnosis: Evidence of at Least Two Distinct Phases From Composite Type 1 Diabetes TrialNet Data

Interpretation of clinical trials to alter the decline in β-cell function after diagnosis of type 1 diabetes depends on a robust understanding of the natural history of disease. Combining data from the Type 1 Diabetes TrialNet studies, we describe the natural history of β-cell function from shortly after diagnosis through 2 years post study randomization, assess the degree of variability between patients, and investigate factors that may be related to C-peptide preservation or loss. We found that 93% of individuals have detectable C-peptide 2 years from diagnosis. In 11% of subjects, there was no significant fall from baseline by 2 years. There was a biphasic decline in C-peptide; the C-peptide slope was −0.0245 pmol/mL/month (95% CI −0.0271 to −0.0215) through the first 12 months and −0.0079 (−0.0113 to −0.0050) from 12 to 24 months (P < 0.001). This pattern of fall in C-peptide over time has implications for understanding trial results in which effects of therapy are most pronounced early and raises the possibility that there are time-dependent differences in pathophysiology. The robust data on the C-peptide obtained under clinical trial conditions should be used in planning and interpretation of clinical trials.

Rituximab Selectively Suppresses Specific Islet Antibodies

OBJECTIVE The TrialNet Study Group evaluated rituximab, a B-cell–depleting monoclonal antibody, for its effect in new-onset patients with type 1A diabetes. Rituximab decreased the loss of C-peptide over the first year of follow-up and markedly depleted B lymphocytes for 6 months after administration. This article analyzes the specific effect of rituximab on multiple islet autoantibodies. RESEARCH DESIGN AND METHODS A total of 87 patients between the ages of 8 and 40 years received either rituximab or a placebo infusion weekly for four doses close to the onset of diabetes. Autoantibodies to insulin (IAAs), GAD65 (GADAs), insulinoma-associated protein 2 (IA2As), and ZnT8 (ZnT8As) were measured with radioimmunoassays. The primary outcome for this autoantibody analysis was the mean level of autoantibodies during follow-up. RESULTS Rituximab markedly suppressed IAAs compared with the placebo injection but had a much smaller effect on GADAs, IA2As, and ZnT8As. A total of 40% (19 of 48) of rituximab-treated patients who were IAA positive became IAA negative versus 0 of 29 placebo-treated patients (P < 0.0001). In the subgroup (n = 6) treated within 50 days of diabetes, IAAs were markedly suppressed by rituximab in all patients for 1 year and for four patients as long as 3 years despite continuing insulin therapy. Independent of rituximab treatment, the mean level of IAAs at study entry was markedly lower (P = 0.035) for patients who maintained C-peptide levels during the first year of follow-up in both rituximab-treated and placebo groups. CONCLUSIONS A single course of rituximab differentially suppresses IAAs, clearly blocking IAAs for >1 year in insulin-treated patients. For the patients receiving insulin for >2 weeks prior to rituximab administration, we cannot assess whether rituximab not only blocks the acquisition of insulin antibodies induced by insulin administration and/or also suppresses preformed insulin autoantibodies. Studies in prediabetic non–insulin-treated patients will likely be needed to evaluate the specific effects of rituximab on levels of IAAs.

VITAMIN D STATUS AND RECURRENT PRETERM BIRTH: A nested case-control study in high-risk women

Please cite this paper as: Thorp J, Camargo C, McGee P, Harper M, Klebanoff M, Sorokin Y, Varner M, Wapner R, Caritis S, Iams J, Carpenter M, Peaceman A, Mercer B, Sciscione A, Rouse D, Ramin S, Anderson G. Vitamin D status and recurrent preterm birth: a nested case–control study in high‐risk women. BJOG 2012;119:1617–1623.

Sample size requirements for studies of treatment effects on beta-cell function in newly diagnosed type 1 diabetes.

Preservation of -cell function as measured by stimulated C-peptide has recently been accepted as a therapeutic target for subjects with newly diagnosed type 1 diabetes. In recently completed studies conducted by the Type 1 Diabetes Trial Network (TrialNet), repeated 2-hour Mixed Meal Tolerance Tests (MMTT) were obtained for up to 24 months from 156 subjects with up to 3 months duration of type 1 diabetes at the time of study enrollment. These data provide the information needed to more accurately determine the sample size needed for future studies of the effects of new agents on the 2-hour area under the curve (AUC) of the C-peptide values. The natural log(), log(+1) and square-root transformations of the AUC were assessed. In general, a transformation of the data is needed to better satisfy the normality assumptions for commonly used statistical tests. Statistical analysis of the raw and transformed data are provided to estimate the mean levels over time and the residual variation in untreated subjects that allow sample size calculations for future studies at either 12 or 24 months of follow-up and among children 8–12 years of age, adolescents (13–17 years) and adults (18+ years). The sample size needed to detect a given relative (percentage) difference with treatment versus control is greater at 24 months than at 12 months of follow-up, and differs among age categories. Owing to greater residual variation among those 13–17 years of age, a larger sample size is required for this age group. Methods are also described for assessment of sample size for mixtures of subjects among the age categories. Statistical expressions are presented for the presentation of analyses of log(+1) and transformed values in terms of the original units of measurement (pmol/ml). Analyses using different transformations are described for the TrialNet study of masked anti-CD20 (rituximab) versus masked placebo. These results provide the information needed to accurately evaluate the sample size for studies of new agents to preserve C-peptide levels in newly diagnosed type 1 diabetes.

Insulin secretion measured by stimulated C‐peptide in long‐established Type 1 diabetes in the Diabetes Control and Complications Trial (DCCT)/ Epidemiology of Diabetes Interventions and Complications (EDIC) cohort: a pilot study

To evaluate whether clinically relevant concentrations of stimulated C‐peptide in response to a mixed‐meal tolerance test can be detected after almost 30 years of diabetes in people included in the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications cohort.

Haptoglobin Phenotype, Preeclampsia Risk and the Efficacy of Vitamin C and E Supplementation to Prevent Preeclampsia in a Racially Diverse Population

Haptoglobin’s (Hp) antioxidant and pro-angiogenic properties differ between the 1-1, 2-1, and 2-2 phenotypes. Hp phenotype affects cardiovascular disease risk and treatment response to antioxidant vitamins in some non-pregnant populations. We previously demonstrated that preeclampsia risk was doubled in white Hp 2-1 women, compared to Hp 1-1 women. Our objectives were to determine whether we could reproduce this finding in a larger cohort, and to determine whether Hp phenotype influences lack of efficacy of antioxidant vitamins in preventing preeclampsia and serious complications of pregnancy-associated hypertension (PAH). This is a secondary analysis of a randomized controlled trial in which 10,154 low-risk women received daily vitamin C and E, or placebo, from 9-16 weeks gestation until delivery. Hp phenotype was determined in the study prediction cohort (n = 2,393) and a case-control cohort (703 cases, 1,406 controls). The primary outcome was severe PAH, or mild or severe PAH with elevated liver enzymes, elevated serum creatinine, thrombocytopenia, eclampsia, fetal growth restriction, medically indicated preterm birth or perinatal death. Preeclampsia was a secondary outcome. Odds ratios were estimated by logistic regression. Sampling weights were used to reduce bias from an overrepresentation of women with preeclampsia or the primary outcome. There was no relationship between Hp phenotype and the primary outcome or preeclampsia in Hispanic, white/other or black women. Vitamin supplementation did not reduce the risk of the primary outcome or preeclampsia in women of any phenotype. Supplementation increased preeclampsia risk (odds ratio 3.30; 95% confidence interval 1.61–6.82, p<0.01) in Hispanic Hp 2-2 women. Hp phenotype does not influence preeclampsia risk, or identify a subset of women who may benefit from vitamin C and E supplementation to prevent preeclampsia.

Use and attitudes of obstetricians toward 3 high-risk interventions in MFMU Network hospitals.

OBJECTIVE We sought to evaluate the frequency of, and factors associated with, the use of 3 evidence-based interventions: antenatal corticosteroids for fetal lung maturity, progesterone for prevention of recurrent preterm birth, and magnesium sulfate for fetal neuroprotection. STUDY DESIGN A self-administered survey was conducted from January through May 2011 among obstetricians from 21 hospitals that included 30 questions regarding their knowledge, attitudes, and practice of the 3 evidence-based interventions and the 14-item short version of the Team Climate for Innovation survey. Frequency of use of each intervention was ascertained from an obstetrical cohort of women between January 2010 and February 2011. RESULTS A total of 329 obstetricians (74% response rate) who managed 16,946 deliveries within the obstetrical cohort participated in the survey. More than 90% of obstetricians reported that they incorporated each intervention into routine practice. Actual frequency of administration in women eligible for the treatments was 93% for corticosteroids, 39% for progesterone, and 71% for magnesium sulfate. Provider satisfaction with quality of treatment evidence was 97% for corticosteroids, 82% for progesterone, and 57% for magnesium sulfate. Obstetricians perceived that barriers to treatment were most frequent for progesterone (76%), 30% for magnesium sulfate, and 17% for corticosteroids. Progesterone use was more frequent among patients whose provider reported the quality of the evidence was above average to excellent compared with poor to average (42% vs 25%, respectively; P < .001), and they were satisfied with their knowledge of the intervention (41% vs 28%; P = .02), and was less common among patients whose provider reported barriers to hospital or pharmacy drug delivery (31% vs 42%; P = .01). Corticosteroid administration was more common among patients who delivered at hospitals with 24 hours a day-7 days a week maternal-fetal medicine specialist coverage (93% vs 84%; P = .046), CONCLUSION: Obstetricians in Maternal-Fetal Medicine Units Network hospitals frequently use these evidence-based interventions; however, progesterone use was found to be related to their assessment of evidence quality. Neither progesterone nor the other interventions were associated with overall climate of innovation within a hospital as measured by the Team Climate for Innovation. National Institutes of Health Consensus Conference Statements may also have an impact on use; there is such a statement for antenatal corticosteroids but not for progesterone for preterm prevention or magnesium sulfate for fetal neuroprotection.

Haptoglobin phenotype and abnormal uterine artery Doppler in a racially diverse cohort

Abstract Objective: The anti-oxidant and proangiogenic protein haptoglobin (Hp) is believed to be important for implantation and pregnancy, although its specific role is not known. The three phenotypes (1-1, 2-1 and 2-2) differ in structure and function. Hp 2-2 is associated with increased vascular stiffness in other populations. We examined whether Hp phenotype is associated with abnormal uterine artery Doppler (UAD) in pregnancy. Methods: We conducted a secondary analysis of a preeclampsia prediction cohort nested within a larger placebo-controlled randomized clinical trial of antioxidants for prevention of preeclampsia. We determined Hp phenotype in 2184 women who completed UAD assessments at 17 weeks gestation. Women with notching were re-evaluated for persistent notching at 24 weeks’ gestation. Logistic regression was used to assess differences in UAD indices between phenotype groups. Results: Hp phenotype did not significantly influence the odds of having any notch (p = 0.32), bilateral notches (p = 0.72), or a resistance index (p = 0.28) or pulsatility index (p = 0.67) above the 90th percentile at 17 weeks’ gestation. Hp phenotype also did not influence the odds of persistent notching at 24 weeks (p = 0.25). Conclusions: Hp phenotype is not associated with abnormal UAD at 17 weeks’ gestation or with persistent notching at 24 weeks.