Comparison of two chromogranin A assays and investigation of nonlinear specimens.

Background: As a marker for functional and non-functional neuroendocrine tumors, serum chromogranin A (CgA) concentrations have shown value for detecting and monitoring disease. Here we describe a comparison between an established micro-titer plate assay (Cisbio CgA ELISA) and an analyzer-based assay (B·R·A·H·M·S CgA II KRYPTOR). Reference limits were established along with a performance evaluation of the KRYPTOR assay. Nonlinearity observed in approximately 0.03% of patients was also investigated. Methods: Samples were tested according to kit manufacturer's protocols. Reference limits were established for both assays testing the same cohort of healthy volunteers. Potential causes of nonlinearity investigated were HAMA, macromolecule effects and elevated serum creatinine. Results: KRYPTOR vs. Cisbio: slope=0.692, y-intercept=-40.0 (r2=0.967, n=186). Upper reference limits were 160 and 103 ng/mL for the Cisbio and KRYPTOR assays, respectively. Linearity: slope=1.012 (r2=0.998) with 95.0-105.5% recoveries. Precision: repeatability ≤2.4%, within-laboratory ≤3.1% (79 and 738 ng/mL). Limit of detection: 8 ng/mL. Strong nonlinear specimens (n=6) retested for HAMA interference generated differences (block-no block) ranging -3.2-4.2%. Polyethylene glycol precipitation recoveries ranged from 157 to >5714% for affected specimens versus 71-79% for normal specimens. Eight of 14 nonlinear specimens (57%) had elevated serum creatinine results (>1.20 mg/dL). Conclusions: The CgA II KRYPTOR assay performs acceptably for quantifying CgA in human serum. While adequate correlation is observed against the Cisbio ELISA, there is significant disagreement overall. Efforts to identify a cause of the nonlinearity observed in a small percentage of patients were inconclusive, but neither HAMA interference, macromolecule effects nor renal failure appear as major factors.

Correction of mildly dysplastic hips with periacetabular osteotomy demonstrates promising outcomes, achievement of correction goals, and excellent five-year survivorship.

AIMS: The aim of this study was to compare patient-reported outcome measures (PROMs), radiological measurements, and total hip arthroplasty (THA)-free survival in patients who underwent periacetabular osteotomy (PAO) for mild, moderate, or severe developmental dysplasia of the hip. PATIENTS AND METHODS: We performed a retrospective study involving 336 patients (420 hips) who underwent PAO by a single surgeon at an academic centre. After exclusions, 124 patients (149 hips) were included. The preoperative lateral centre-edge angle (LCEA) was used to classify the severity of dysplasia: 18° to 25° was considered mild (n = 20), 10° to 17° moderate (n = 66), and < 10° severe (n = 63). There was no difference in patient characteristics between the groups (all, p > 0.05). Pre- and postoperative radiological measurements were made. The National Institute of Health's Patient Reported Outcomes Measurement Information System (PROMIS) outcome measures (physical function computerized adaptive test (PF CAT), Global Physical and Mental Health Scores) were collected. Failure was defined as conversion to THA or PF CAT scores < 40, and was assessed with Kaplan-Meier analysis. The mean follow-up was five years (2 to 10) ending in either failure or the latest contact with the patient. RESULTS: There was no significant difference in PROMs for moderate (p = 0.167) or severe (p = 0.708) groups compared with the mild dysplasia group. The numerical pain scores were between 2 and 3 units in all groups at the final follow-up (all, p > 0.05). There was no significant difference (all, p > 0.05) in the proportion of patients achieving target correction for the LCEA between groups. The mean correction was 12° in the mild, 15° in the moderate (p = 0.135), and 23° in the severe group (p < 0.001). Failure-free survival at five years was 100% for mild, 79% for moderate, and 92% for severely dysplastic hips (p = 0.225). CONCLUSION: Although requiring less correction than hips with moderate or severe dysplasia, we found PAO for mild dysplasia to be associated with promising PROMs, consistent with that of the general United States population, and excellent survivorship at five years. Future studies should compare these results with the outcome after arthroscopy of the hip in patients with mild dysplasia. Cite this article: Bone Joint J 2019;101-B(6 Supple B):16-22.

MRI in idiopathic, stable, slipped capital femoral epiphysis: evaluation of contralateral pre-slip.

PURPOSE: Early diagnosis and treatment of slipped capital femoral epiphysis (SCFE) is important to prevent slip progression and avoid complications. We sought to determine if MRI findings in patients with unilateral SCFE could indicate 'pre-slip' or predict future SCFE in the contralateral hip. METHODS: A prospective study evaluated patients with unilateral SCFE over a two-year period. MRI of the asymptomatic hip was performed within the perioperative period. Patients were followed with radiographs until a contralateral slip occurred or until physeal closure. Demographics, clinical stability, severity, posterior slope angle (PSA), modified Oxford Bone Score (mOBS) and patency of the triradiate cartilage were recorded and statistical analysis performed. RESULTS: In all, 33 of 54 patients with unilateral SCFE were enrolled into the study. In all, 29 (87.8%) had complete follow-up. Five of the enrolled patients (15.2%) developed a sequential slip requiring in situ pinning. Six of 33 (18.2%) patients had positive MRI findings: four of which proceeded to sequential SCFE and two which did not. One sequential slip had a negative MRI. PSA predicted 1/11 sequential slips (sensitivity 9.09%, specificity 81.4%, positive predictive value (PPV) 11.1%, negative predictive value (NPV) 77.8%) and mOBS predicted 5/11 sequential slips (sensitivity 45.5%, specificity 93%, PPV 62.5%, NPV 87%). An open triradiate cartilage was present in 8/11 patients with sequential slips (sensitivity 72.7%, specificity 81.4%, PPV 50%, NPV 92.1%). CONCLUSION: MRI findings consistent with 'pre-slip' were present in 66.7% of patients who developed a sequential SCFE. Further study on the utility/sensitivity of MRI in predicting sequential SCFE is warranted. LEVEL OF EVIDENCE: II, diagnostic.

Mitochondrial metabolism directs stemness and differentiation in P19 embryonal carcinoma stem cells.

The relationship between mitochondrial metabolism and cell viability and differentiation in stem cells (SCs) remains poorly understood. In the present study, we compared mitochondrial physiology and metabolism between P19SCs before/after differentiation and present a unique fingerprint of the association between mitochondrial activity, cell differentiation and stemness. In comparison with their differentiated counterparts, pluripotency of P19SCs was correlated with a strong glycolytic profile and decreased mitochondrial biogenesis and complexity: round, low-polarized and inactive mitochondria with a closed permeability transition pore. This decreased mitochondrial capacity increased their resistance against dichloroacetate. Thus, stimulation of mitochondrial function by growing P19SCs in glutamine/pyruvate-containing medium reduced their glycolytic phenotype, induced loss of pluripotent potential, compromised differentiation and became P19SCs sensitive to dichloroacetate. Because of the central role of this type of SCs in teratocarcinoma development, our findings highlight the importance of mitochondrial metabolism in stemness, proliferation, differentiation and chemoresistance. In addition, the present work suggests the regulation of mitochondrial metabolism as a tool for inducing cell differentiation in stem line therapies.

Diabetes, pre-diabetes and insulin resistance screening in Native American children and youth.

OBJECTIVES: Early identification of pre-diabetes and insulin resistance (IR) provides an important window of opportunity for diabetes prevention. Little is known about the prevalence of pre-diabetes and IR in Native American (NA) youth. We designed a cross-sectional, community-based study of NA children to estimate the prevalence of diabetes, pre-diabetes and IR and their association with other diabetes risk factors. STUDY DESIGN: NA children (5-18 years) were screened with body mass index (BMI), blood pressure, oral glucose tolerance test (OGTT), lipids, insulin and highly sensitive C-reactive protein (hsCRP), and calculated homeostatic model assessment of IR (HOMA-IR). RESULTS: Mean age of the cohort (n=201) was 10.8 ± 3.8 years (± s.d.; 94/107 M/F). BMI percentile for age and sex (BMI%) was elevated (≥ 85 th percentile) in 58.6% of 5-11 years and 51.1% of 12-18 years, and positively correlated with HOMA-IR, blood pressure, triglycerides and hsCRP (P<0.05). The prevalence rate for pre-diabetes and diabetes were 6.5% (3.5-10.8%) and 1.0% (0.1-3.6%), respectively. Mean HOMA-IR was greater in the older than younger age group while prevalence of pre-diabetes was the same. Those with pre-diabetes and diabetes had a greater HOMA-IR, abdominal circumference and BMI% than normal youth. CONCLUSION: In the first prospective, community-based screening for pre-diabetes, IR and diabetes in United States NA youth using OGTT, while the number of diabetes cases was low, pre-diabetes was found in a significant number of youth, particularly in those with BMI ≥ 95 th%. As proportions of pre-diabetes were similar in 5-11 and 12-18 year olds, diabetes risk begins early in NA youth.

Comparison of three assays for quantifying S-100B in serum.

BACKGROUND: Serum S-100B has clinical value in monitoring malignant melanoma and in monitoring and predicting outcomes in patients with traumatic brain injury. METHODS: Analytical performance characteristic and split-sample method comparison studies for three commercial S-100B immunoassays (CanAg® S100, Sangtec® 100, YK150 Human S-100 ß) were performed. Reference intervals (97.5th percentile) for each assay were established by non-parametric analysis of results from healthy volunteers. RESULTS: Linearity results were slope=1.014, intercept=65.1, r(2)=0.999 for the Sangtec assay; slope=1.038, intercept=31.1, r(2)=0.999 for the CanAg assay; slope=1.123, intercept=-105.4, r(2)=0.997 for the YK150 assay. Within-run CVs were ≤5.7, ≤6.3 and ≤10.8 for the Sangtec, CanAg and YK150 ELISAs, respectively. Between-run CVs were ≤11.3, ≤5.9 and ≤9.5, respectively. Upper reference interval limits of 141, 96 and 735 ng/l S-100B were established for the Sangtec, CanAg and YK150 ELISAs, respectively. Deming regression generated the following: CanAg vs. Sangtec, slope=0.339, intercept=24.1, r(2)=0.932; YK150 vs. Sangtec, slope=0.266, intercept=-140.0, r(2)=0.690; YK150 vs. CanAg, slope=1.376, intercept=-13.1, r(2)=0.860. CONCLUSIONS: The configurations, procedures and performance characteristics of the Sangtec and CanAg S-100B ELISAs are comparable and better than those of the YK150 assay. Poor agreement and large biases prevent interchangeable use of results.

The art and science of cancer education and evaluation: toward facilitating improved patient outcomes.

Cancer education is a constantly evolving field, as science continues to advance both our understanding of cancer and its effects on patients, families, and communities. Moving discoveries to practice expeditiously is paramount to impacting cancer outcomes. The continuing education of cancer care professionals throughout their practice life is vital to facilitating the adoption of therapeutic innovations. Meanwhile, more general educational programs serve to keep cancer patients, their families, and the public informed of the latest findings in cancer research. The National Cancer Institute conducted an assessment of the current knowledge base for cancer education which involved two literature reviews, one of the general literature of the evaluation of medical and health education efforts, and the other of the preceding 5 years of the Journal of Cancer Education (JCE). These reviews explored a wide range of educational models and methodologies. In general, those that were most effective used multiple methodologies, interactive techniques, and multiple exposures over time. Less than one third of the articles in the JCE reported on a cancer education or communication product, and of these, only 70% had been evaluated for effectiveness. Recommendations to improve the evaluation of cancer education and the educational focus of the JCE are provided.

Structure of a novel dodecaheme cytochrome c from Geobacter sulfurreducens reveals an extended 12 nm protein with interacting hemes.

Multiheme cytochromes c are important in electron transfer pathways in reduction of both soluble and insoluble Fe(III) by Geobacter sulfurreducens. We determined the crystal structure at 3.2Å resolution of the first dodecaheme cytochrome c (GSU1996) along with its N-terminal and C-terminal hexaheme fragments at 2.6 and 2.15Å resolution, respectively. The macroscopic reduction potentials of the full-length protein and its fragments were measured. The sequence of GSU1996 can be divided into four c(7)-type domains (A, B, C and D) with homology to triheme cytochromes c(7). In cytochromes c(7) all three hemes are bis-His coordinated, whereas in c(7)-type domains the last heme is His-Met coordinated. The full-length GSU1996 has a 12nm long crescent shaped structure with the 12 hemes arranged along a polypeptide to form a "nanowire" of hemes; it has a modular structure. Surprisingly, while the C-terminal half of the protein consists of two separate c(7)-type domains (C and D) connected by a small linker, the N-terminal half of the protein has two c(7)-type domains (A and B) that form one structural unit. This is also observed in the AB fragment. There is an unexpected interaction between the hemes at the interface of domains A and B, which form a heme-pair with nearly parallel stacking of their porphyrin rings. The hemes adjacent to each other throughout the protein are within van der Waals distance which enables efficient electron exchange between them. For the first time, the structural details of c(7)-type domains from one multiheme protein were compared.

Performance characteristics of an automated assay for the quantitation of CYFRA 21-1 in human serum.

OBJECTIVES: A fragment of cytokeratin 19, CYFRA 21-1, has been reported to be a sensitive tumor marker for non-small cell lung cancer (NSCLC). We describe analytical performance characteristics of a novel CYFRA 21-1 assay and hypothesize that CYFRA 21-1 complements the clinical sensitivity of carcinoembryonic antigen (CEA) and squamous cell carcinoma antigen (SCCa). DESIGN AND METHODS: Performance characteristics of a CYFRA 21-1 immunochemiluminescent assay included analytical sensitivity, imprecision, linearity, analyte stability, and reference interval determination. Ninety-two pretreatment NSCLC serum samples were tested for CYFRA 21-1, CEA, and SCCa. Sensitivity was determined for each marker individually and in combination, with regard to tumor stage and histology. RESULTS: The analytical sensitivity was 0.01 ng/mL. Total imprecision ranged from 4.0 to 6.3% at 4.9 to 28.4 ng/mL, respectively. The assay was linear from 0.9 to 71.4 ng/mL (slope=0.995, intercept=-0.60, r(2)=0.999). CYFRA 21-1 was stable for 48 h at ambient temperature and 14 days at 4°C. The 97.5th percentile of a reference population was 1.9 ng/mL. Across disease stage, the sensitivities of CYFRA 21-1, CEA, and SCCa were 17-81%, 30-52%, and 24-39%, respectively. CYFRA 21-1 combined with CEA or SCCa increased sensitivity above that of any single marker. CONCLUSIONS: An immunochemiluminescent assay for CYFRA 21-1 had favorable performance characteristics. CYFRA 21-1 was complementary to CEA and SCCa and increased clinical sensitivity in patients with NSCLC.

Immunoassay for quantifying squamous cell carcinoma antigen in serum.

BACKGROUND: Although the benefits of quantifying serum squamous cell carcinoma antigen (SCCa) have been reported, SCCa reagents were no longer available in the US by the late 1990s. Because SCCa quantification still has demonstrated clinical utility, we developed and validated a microtiter plate-based ELISA for measuring SCCa in serum. METHODS: We coated microtiter strips overnight with capture anti-SCCa monoclonal antibody, washed the wells, added blocking buffer, and lyophilized the strips. For detection, we used a biotinylated anti-SCCa detection antibody, streptavidin/horseradish peroxidase conjugate, and tetramethylbenzidine/H(2)O(2) substrate. A novel blocking reagent against human antimouse antibodies (HAMA) was evaluated. A reference interval was established with sera from healthy individuals and was confirmed in smokers. RESULTS: The assay was linear to 40 microg/L SCCa (slope, 1.00; y intercept, 0.695; R(2), 0.996) with a detection limit of 0.3 microg/L. The intraassay imprecision results [mean (CV)] were 2.5 microg/L (3.4%), 18.0 microg/L (3.0%), and 30.7 microg/L (2.4%); interassay imprecision results were 2.0 microg/L (9.9%), 20.0 microg/L (7.6%), and 36.3 microg/L (3.5%). A correlation analysis against an established automated assay generated a slope of 0.976 and a y intercept of -0.193 microg/L (r(2) = 0.916). An upper reference limit of 2.1 microg/L SCCa was established at 95% confidence level, with no difference observed in smokers. No correlation between SCCa concentration and age was observed (r(2) = 0.0003). At a blocking reagent concentration of 5 mg/L, HAMA interference was eliminated in 3 samples known to produce falsely increased SCCa results. CONCLUSIONS: This SCCa ELISA demonstrates acceptable performance characteristics for quantifying serum SCCa and is effective in eliminating HAMA interference.

Teratology: from science to birth defects prevention.

One of the goals of birth defects research is to better understand risk or preventive factors for birth defects so that strategies for prevention can be developed. In this article, we have selected four areas of birth defects research that have led to the development of prevention strategies. These areas include rubella virus as a cause of congenital rubella syndrome, folic acid as a preventive factor for neural tube defects, cytomegalovirus infection as a cause of birth defects and developmental disabilities, and alcohol as a cause of fetal alcohol spectrum disorders. For each of these areas, we review key clinical and research findings that led to the identification of the risk or preventive factor, milestones in the development of prevention strategies, and the progress made thus far toward prevention.

Performance characteristics of the Access Inhibin A assay.

BACKGROUND: Second trimester maternal screening using AFP, uE3, hCG, and inhibin A has shown a detection rate for Down's syndrome of 81% with a 5% false positive rate. Inhibin A may also have utility as a serum tumor marker in postmenopausal women with ovarian cancer and men with testicular stromal tumors. METHODS: The Beckman Coulter Access Inhibin A assay was evaluated for limit of blank, dilution linearity, imprecision, interferences, reference intervals, and comparison to an inhibin A ELISA. RESULTS: The limit of blank was 0.1 ng/l. The assay was linear from 0.2 to 1347 ng/l. Total inter-assay CVs were <5% for control levels ranging from 24.6 ng/l to 811 ng/l. Interference studies showed recoveries of inhibin A within 10% of expected values at interferent concentrations of 10 g/l hemoglobin and 22 g/l triglycerides. No significant interference was observed at a bilirubin concentration of 400 mg/l. The 97.5th percentile upper reference limits were 6.8 ng/l for postmenopausal women and 3.0 ng/l for men. The Access assay compared to an ACTIVE ELISA showed a slope of 0.88, an intercept of -3.7 ng/l, S(y/x)=40 ng/l, and r=0.98. CONCLUSIONS: The analytical performance of the Access inhibin A assay is acceptable for routine laboratory testing.

Prevalence and effects of gene-gene and gene-nutrient interactions on serum folate and serum total homocysteine concentrations in the United States: findings from the third National Health and Nutrition Examination Survey DNA Bank.

BACKGROUND: Abnormalities of folate and homocysteine metabolism are associated with a number of pediatric and adult disorders. Folate intake and genetic polymorphisms encoding folate-metabolizing enzymes influence blood folate and homocysteine concentrations, but the effects and interactions of these factors have not been studied on a population-wide basis. OBJECTIVE: The objective was to assess the prevalence of these genetic polymorphisms and their relation to serum folate and homocysteine concentrations. DESIGN: DNA samples from 6793 participants in the third National Health and Nutrition Examination Survey (NHANES III) during 1991-1994 were genotyped for polymorphisms of genes coding for folate pathway enzymes 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C-->T and 1298A-->C, methionine synthase reductase (MTRR) 66A-->G, and cystathionine-beta-synthase 844ins68. The influence of these genetic variants on serum folate and homocysteine concentrations was analyzed by age, sex, and folate intake in 3 race-ethnicity groups. RESULTS: For all race-ethnicity groups, serum folate and homocysteine concentrations were significantly related to the MTHFR 677C-->T genotype but not to the other polymorphisms. Persons with the MTHFR 677 TT genotype had a 22.1% (95% CI: 14.6%, 28.9%) lower serum folate and a 25.7% (95% CI: 18.6%, 33.2%) higher homocysteine concentration than did persons with the CC genotype. Moderate daily folic acid intake (mean: 150 microg/d; 95% CI: 138, 162) significantly reduced the difference in mean homocysteine concentrations between those with the MTHFR 677 CC and TT genotypes. We found a significant interaction between MTHFR 677C-->T and MTRR 66A-->G on serum homocysteine concentrations among non-Hispanic whites. CONCLUSIONS: The MTHFR 677C-->T polymorphism was associated with significant differences in serum folate and homocysteine concentrations in the US population before folic acid fortification. The effect of MTHFR 677C-->T on homocysteine concentrations was reduced by moderate daily folic acid intake.

1-year follow-up of autologous muscle-derived stem cell injection pilot study to treat stress urinary incontinence.

We hereby report a 1-year follow-up on eight women in the first North America trial in which stress urinary incontinence (SUI) was treated with muscle-derived stem cell injections. Mean and median follow-up in this group was 16.5 and 17 months (range 3-24 months). Improvement in SUI was seen in five of eight women, with one achieving total continence. Onset of improvement was between 3 and 8 months after injection. Cure or improvement continued at a median of 10 months. No serious adverse events were reported.

Race-ethnicity differences in folic acid intake in women of childbearing age in the United States after folic acid fortification: findings from the National Health and Nutrition Examination Survey, 2001-2002.

BACKGROUND: Neural tube defects are serious birth defects of the brain and spinal cord. Up to 70% of neural tube defects can be prevented by the consumption of folic acid by women before and early during pregnancy. OBJECTIVE: The objective was to examine folic acid intake in women of childbearing age in the United States. DESIGN: We analyzed nutrient intake data reported by 1685 nonpregnant women aged 15-49 y who participated in the National Health and Nutritional Examination Survey, 2001-2002. RESULTS: The adjusted geometric mean consumption of folic acid from fortified foods was 128 microg/d (95% CI: 123, 134 microg/d) in nonpregnant women. Eight percent (95% CI: 5.8%, 11.0%) of nonpregnant women reported consuming >or=400 microg folic acid/d from fortified foods. This proportion was lower among non-Hispanic black women (5.0%) than among non-Hispanic white (8.9%) or Hispanic (6.8%) women. A smaller percentage of non-Hispanic black (19.1%) and Hispanic (21%) women than of non-Hispanic white women (40.5%) consumed >or=400 microg folic acid from supplements, fortified foods, or both, in addition to food folate, as recommended by the Institute of Medicine to reduce the frequency of neural tube defects. CONCLUSIONS: Most nonpregnant women of childbearing age in the United States reported consuming less than the recommended amount of folic acid. The proportion with low daily folic acid intake was significantly higher in non-Hispanic black and Hispanic women than in non-Hispanic white women. At the present level of folic acid fortification, most women need to take a folic acid-containing dietary supplement to achieve the Institute of Medicine recommendation.

International retrospective cohort study of neural tube defects in relation to folic acid recommendations: are the recommendations working?

OBJECTIVES: To evaluate the effectiveness of policies and recommendations on folic acid aimed at reducing the occurrence of neural tube defects. DESIGN: Retrospective cohort study of births monitored by birth defect registries. SETTING: 13 birth defects registries monitoring rates of neural tube defects from 1988 to 1998 in Norway, Finland, Northern Netherlands, England and Wales, Ireland, France (Paris, Strasbourg, and Central East), Hungary, Italy (Emilia Romagna and Campania), Portugal, and Israel. Cases of neural tube defects were ascertained among liveborn infants, stillbirths, and pregnancy terminations (where legal). Policies and recommendations were ascertained by interview and literature review. MAIN OUTCOME MEASURES: Incidences and trends in rates of neural tube defects before and after 1992 (the year of the first recommendations) and before and after the year of local recommendations (when applicable). RESULTS: The issuing of recommendations on folic acid was followed by no detectable improvement in the trends of incidence of neural tube defects. CONCLUSIONS: Recommendations alone did not seem to influence trends in neural tube defects up to six years after the confirmation of the effectiveness of folic acid in clinical trials. New cases of neural tube defects preventable by folic acid continue to accumulate. A reasonable strategy would be to quickly integrate food fortification with fuller implementation of recommendations on supplements.

Lattice gas 2D/3D equilibria: chemical potentials and adsorption isotherms with correct critical points.

A priori information is used to derive the chemical potential as a function of density and temperature for 2D and 3D lattice systems. The functional form of this equation of state is general in terms of lattice type and dimensionality, though it contains critical temperature and critical density as parameters which depend on lattice type and dimensionality. The adsorption isotherm is derived from equilibrium between two-dimensional and three-dimensional phases. Theoretical predictions are in excellent agreement with grand canonical Monte Carlo simulations.

Folic acid supplements during early pregnancy and likelihood of multiple births: a population-based cohort study.

BACKGROUND: Folic acid supplements are recommended for women of childbearing age to prevent neural tube defects in their offspring. Results of some studies, however, suggest an increase in multiple births associated with use of vitamin supplements that contain folic acid during pregnancy. Our aim was to assess this association. METHODS: We used data from a population-based cohort study from which we assessed the occurrence of multiple births in women (n=242015) who had participated in a campaign to prevent neural tube defects with folic acid supplements (400 microg per day) in China. Folic acid use was ascertained before pregnancy outcome was known. We studied the relation between multiple births and any use of folic acid pills before or during early pregnancy; additionally, we investigated mechanisms by which folic acid could potentially affect the occurrence of multiple births by examining pill-taking at three time periods: before ovulation, around the time of fertilisation, and after conception. FINDINGS: 1496 (0.62%) multiple births occurred in a cohort of 242015 women who had registered with the study between October, 1993, and September, 1995, and who had a pregnancy not affected by a birth defect; the rate of multiple births in women who did and did not take folic acid before or during early pregnancy was 0.59% and 0.65%, respectively (rate ratio 0.91; 95% CI 0.82-1.00). INTERPRETATION: Our findings suggest that consumption of folic acid supplements during pregnancy is not associated with an increased occurrence of multiple births.

Method of weighted proportion of reproductive-aged women taking folic acid supplements to predict a neural tube defect rate decline.

BACKGROUND: Neural tube defect (NTD) rates can be lowered by increased consumption of folic acid (FA) by women before and during early pregnancy. The crude proportion of reproductive-aged women taking FA supplements has been used to predict a decline of the NTD rate in the general population. In this study we examine the potential error in using the crude proportion to predict NTD risk reduction, and offer an alternative method. METHODS: The crude proportion measures the number of women taking FA. It ignores the substantial variability by maternal age in the probability of giving birth. Age-specific fertility rates (ASFRs) reflect the probability that a woman in a specific age group will give birth in a given year. In this study, we show how to calculate a proportion weighted by ASFRs to predict a decline in the NTD rate, and to assess the effectiveness of FA consumption in preventing NTDs. RESULTS: Our results show that a crude proportion of 50% of women (15-49 years old) taking FA is associated with a range of 24-77% in weighted proportions. Assuming a 40% risk reduction from taking 400 microg of FA daily, the expected NTD rate decline could vary from 9.6% to 30.6%, depending on the age distribution of women taking FA. CONCLUSIONS: The ASFR-weighted proportion estimates the proportion of babies born to women taking FA, as opposed to the crude proportion of women taking FA. We recommend using the ASFR-weighted proportion to predict an NTD rate decline and measure the success of FA education campaigns. We found that when women in high-fertility age groups increased their FA consumption, the decline in the NTD rate was greater than when women in low-fertility age groups did so. Our findings suggest that the more efficient approach to NTD prevention is to focus on women with a higher probability of giving birth. For example, by focusing on <50% of women of childbearing age (20-34 years), as much as 76% of the maximum NTD rate reduction can be achieved.