Evaluation of the risk of cardiovascular events with clarithromycin using both propensity score and self-controlled study designs

Aim: Some previous studies suggest a long term association between clarithromycin use and cardiovascular events. This study investigates this association for clarithromycin given as part of Helicobacter pylori treatment (HPT). Methods: Our source population was the Clinical Practice Research Datalink (CPRD), a UK primary care database. We conducted a self-controlled case series (SCCS), a case–time–control study (CTC) and a propensity score adjusted cohort study comparing the rate of cardiovascular events in the 3 years after exposure to HPT containing clarithromycin with exposure to clarithromycin free HPT. Outcomes were first incident diagnosis of myocardial infarction (MI), arrhythmia and stroke. For the cohort analysis we included secondary outcomes all cause and cardiovascular mortality. Results: Twenty-eight thousand five hundred and fifty-two patients were included in the cohort. The incidence rate ratio of first MI within 1 year of exposure to HPT containing clarithromycin was 1.07 (95% CI 0.85, 1.34, P = 0.58) and within 90 days was 1.43 (95% CI 0.99, 2.09 P = 0.057) in the SCCS analysis. CTC and cohort results were consistent with these findings. Conclusions There was some evidence for a short term association for first MI but none for a long term association for any outcome

Self-controlled case series methodology

The self-controlled case series method is an epidemiological study design in which individuals act as their own control. The method offers advantages, but has several limitations. This paper outlines the self control case series method and reviews methodological developments that address some of these limitations

Myocardial infarction and cardiac death associated with current use of clarithromycin: cohort study

Poste

Myocardial infarction associated with current use of helicobacter pylori eradication regimen containing clarithromycin: self controlled case series

Poste

Association of maternal vitamin B12 and folate levels in early pregnancy with gestational diabetes: a prospective UK cohort study (PRiDE study)

Aims/hypothesis: The prevalence of gestational diabetes mellitus (GDM) is increasing worldwide in all ethnic groups. Low vitamin B12 and low/high folate levels may contribute to GDM risk, but there is conflicting evidence. Our aim is to assess the relationships of early pregnancy vitamin B12 and folate levels with the risk of GDM status at 26–28 weeks of gestation. Methods: This was a prospective, multi-centre, multi-ethnic cohort study (n = 4746) in the UK. Participants who were eligible to be selectively screened as per the National Institute for Health and Care Excellence (NICE) criteria were included in the study. Results: GDM prevalence was 12.5% by NICE and 14.7% by International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria. Folate deficiency (1.3%) was rare but B12 insufficiency (42.3% at < 220 pmol/l) and folate excess (36.5%) were common in early pregnancy. Early pregnancy median B12 levels were lower, and folate levels higher, in women who were diagnosed with GDM at 26–28 weeks. B12 was negatively associated with fasting plasma glucose (1 SD: −0.06 mmol/l; 95% CI −0.04, −0.08; p <  0.0001) and 2 h plasma glucose levels (−0.07 mmol/l; 95% CI −0.02, −0.12; p = 0.004). Higher B12 was associated with 14.4% lower RR of IADPSG-GDM (0.856; 95% CI 0.786, 0.933; p = 0.0004) after adjusting for key confounders (age, parity, smoking status, ethnicity, family history, household income and folate status). Approximately half of this association was mediated through BMI. Folate was positively associated with 2 h plasma glucose levels (0.08 mmol/l; 95% CI 0.04, 0.13; p = 0.0005) but its relationship with fasting plasma glucose was U-shaped (quadratic β: 0.011; p = 0.05). Higher folate was associated with 11% higher RR of IADPSG-GDM (adjusted RR 1.11; 95% CI 1.036, 1.182; p = 0.002) (age, parity, smoking status, ethnicity, family history, household income and B12 status). Although no interactions were observed for B12 and folate (as continuous variables) with glucose levels and GDM risk, a low B12–high folate combination was associated with higher blood glucose level and risk of IADPSG-GDM (adjusted RR 1.742; 95% CI 1.226, 2.437; p = 0.003). Conclusions/interpretation: B12 insufficiency and folate excess were common in early pregnancy. Low B12 and high folate levels in early pregnancy were associated with small but statistically significant changes in maternal blood glucose level and higher RR of GDM. Our findings warrant additional studies on the role of unmetabolised folic acid in glucose metabolism and investigating the effect of optimising early pregnancy or pre-conception B12 and folate levels on subsequent hyperglycaemia