Post-polypectomy Bleeding in Patients on Clopidogrel
Post-polypectomy Bleeding in Patients on Clopidogrel
A systematic search was conducted to retrieve studies that investigated the risk of colonoscopic PPB in patients on continued clopidogrel therapy. We identified potential English-language sources from the Pubmed, Medline and EMBASE databases from 1950 to March 2013. Keywords used were 'clopidogrel, thienopyridine' and 'colonoscopy, polypectomy'. In addition, reference lists of any studies meeting inclusion criteria were reviewed to identify additional relevant publications by manual search.
Studies were included if they met the following criteria: (i) subjects included patients on continued clopidogrel therapy who underwent colonoscopic polypectomy; (ii) a control group included patients who were not taking clopidogrel who underwent colonoscopic polypectomy; (iii) subjects were not on concomitant anticoagulant therapy such as vitamin K antagonists (warfarin) or heparin; (iv) immediate PPB was defined as observed bleeding at the time of the procedure, delayed PPB was defined as observed bleeding that occurred within 30 days of the procedure; (v) studies reported PPB as clinically significant observed bleeding requiring hospitalisation, red cell transfusion or endoscopic re-evaluation; and (vi) published as a full article in the English. Eligibility assessment and data extraction were carried out independently by two investigators (SG and NN) with discrepancies resolved by consensus in consultation with the senior author.
The primary outcome of interest was the pooled relative risk ratio (RR) of colonoscopic PPB in patients on continued clopidogrel therapy vs. controls. Secondary outcomes were a comparison of immediate and delayed colonoscopy PPB in patients on continued clopidogrel therapy vs. controls.
Quality assessment was carried out independently by two investigators (SG and NN) using the Newcastle-Ottawa quality assessment scale. We assessed eligible studies by three criteria: the selection of the study groups (0–4 points), the comparability of the groups (0–2 points) and the ascertainment of either the exposure or outcome of interest (0–3 points), with a total score of 9. A score ≥5 was adequate for inclusion in the meta-analysis. Discrepancies in interpretation of data and inclusion of studies were resolved by in consultation with the senior author.
Meta-analysis was conducted by combining the risk ratios of individual studies into a pooled risk ratio using a random-effects model. Relative risk ratios are reported with 95% confidence intervals. We tested for heterogeneity using the chi-squared test and the I test. The I test describes the percentage of variability in effect estimates that is due to heterogeneity rather than chance. A value of 25% suggests low variability, 50% suggests moderate variability and 75% suggests high variability between studies. Funnel plots were constructed to assess for publication bias. Analyses were performed with RevMan 5.1 [Review Manager (RevMan) [Computer program] Version 5.1. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2011].
Methods
A systematic search was conducted to retrieve studies that investigated the risk of colonoscopic PPB in patients on continued clopidogrel therapy. We identified potential English-language sources from the Pubmed, Medline and EMBASE databases from 1950 to March 2013. Keywords used were 'clopidogrel, thienopyridine' and 'colonoscopy, polypectomy'. In addition, reference lists of any studies meeting inclusion criteria were reviewed to identify additional relevant publications by manual search.
Inclusion/Exclusion Criteria
Studies were included if they met the following criteria: (i) subjects included patients on continued clopidogrel therapy who underwent colonoscopic polypectomy; (ii) a control group included patients who were not taking clopidogrel who underwent colonoscopic polypectomy; (iii) subjects were not on concomitant anticoagulant therapy such as vitamin K antagonists (warfarin) or heparin; (iv) immediate PPB was defined as observed bleeding at the time of the procedure, delayed PPB was defined as observed bleeding that occurred within 30 days of the procedure; (v) studies reported PPB as clinically significant observed bleeding requiring hospitalisation, red cell transfusion or endoscopic re-evaluation; and (vi) published as a full article in the English. Eligibility assessment and data extraction were carried out independently by two investigators (SG and NN) with discrepancies resolved by consensus in consultation with the senior author.
Outcomes of Interest
The primary outcome of interest was the pooled relative risk ratio (RR) of colonoscopic PPB in patients on continued clopidogrel therapy vs. controls. Secondary outcomes were a comparison of immediate and delayed colonoscopy PPB in patients on continued clopidogrel therapy vs. controls.
Study Quality and Data Extraction
Quality assessment was carried out independently by two investigators (SG and NN) using the Newcastle-Ottawa quality assessment scale. We assessed eligible studies by three criteria: the selection of the study groups (0–4 points), the comparability of the groups (0–2 points) and the ascertainment of either the exposure or outcome of interest (0–3 points), with a total score of 9. A score ≥5 was adequate for inclusion in the meta-analysis. Discrepancies in interpretation of data and inclusion of studies were resolved by in consultation with the senior author.
Statistical Analysis
Meta-analysis was conducted by combining the risk ratios of individual studies into a pooled risk ratio using a random-effects model. Relative risk ratios are reported with 95% confidence intervals. We tested for heterogeneity using the chi-squared test and the I test. The I test describes the percentage of variability in effect estimates that is due to heterogeneity rather than chance. A value of 25% suggests low variability, 50% suggests moderate variability and 75% suggests high variability between studies. Funnel plots were constructed to assess for publication bias. Analyses were performed with RevMan 5.1 [Review Manager (RevMan) [Computer program] Version 5.1. Copenhagen: The Nordic Cochrane Centre, The Cochrane Collaboration, 2011].
