Sambu N, Dent H, Englyst N, et al. Effect of clopidogrel withdrawal on platelet reactivity and vascular inflammatory biomarkers 1 year after drug-eluting stent implantation: results of the prospective, single-centre CESSATION study. Heart 2011;97:1661-67.
PubMed link: https://www.ncbi.nlm.nih.gov/pubmed/21795297
Full text article: https://heart.bmj.com/content/heartjnl/97/20/1661.full.pdf
| Methods | Study design: Before-and-after study
Number of groups: One group |
| Participants | Number of participants: 38 enrolled, 33 completed
Age: 65.9 ± 8.2 years Sex: 2 females, 31 males Participants with dementia: No Inclusion criteria · Receiving low-dose aspirin treatment · Undergone percutaneous coronary intervention with drug-eluting stent 11 months earlier · Due to stop clopidogrel at one year Exclusion criteria: · Taking non-steroidal anti-inflammatory drugs, steroids or anticoagulant treatment Country: England Setting: Community – further details |
| Interventions | Medicine: Clopidogrel 75mg daily – total duration of clopidogrel treatment after percutaneous coronary intervention was 373 ± 7.1 days
Withdrawal schedule: Not described |
| Outcomes | Clinical events
Concomitant medical treatment and platelet reactivity Thromboxane B2 levels Adenosine diphosphate (ADP)-induced platelet aggregation Arachidonic acid-induced platelet aggregation Inflammatory biomarkers |
| Dates | Dates: February to June 2010
Follow-up duration: Four weeks |
| Funding sources | Unrestricted grants from Haemonetics and Medtronic UK. |
| Notes | Authors declaration of conflict of interest: “NC has received unrestricted research funding from Haemonetics, Medtronic, Boston Scientific and Pfizer. He has also received speaker/consulting fees from Boston Scientific, Abbott, Medtronic, AstraZeneca, Eli Lilly and Cordis. TW has received unrestricted research funding and speaker/consulting fees from AstraZeneca. JM has received honoraria and consulting fees from Medtronic and St. Jude. The remaining authors report no conflicts of interest. |
Risk of bias table
| Bias | Authors’ judgment | Support for judgment |
| Random sequence generation (selection bias) | High risk | Not randomized. |
| Allocation concealment (selection bias) | High risk | No concurrent control group. |
| Blinding of participants and personnel (performance bias) | 5 out of 5 | Open study. |
| Blinding of outcome assessment (detection bias) | 5 out of 5 | Open study. |
| Incomplete outcome data (attrition bias) | 5 out of 5 | 5/38 patients withdrew for unknown reasons, which may have been related to the intervention. Analysis was then “as-treated”. |
| Selective reporting (reporting bias) | 1 out of 5 | There was a pre-specified protocol, but it is unclear how closely the researchers adhered to a pre-specified analysis plan. However, the stated objectives were reported in addition to clinical events and the effects of two concurrent medicines. All specified outcome measures were reported. |
| Confounding (non-randomized) | 5 out of 5 | No concurrent control group.
Few confounders considered. No mention of other drugs which may impact e.g. SSRIs. |
| Other bias | Low risk | |
| Newcastle-Ottawa scale | ||
| Selection bias | Representativeness of the exposed cohort | Truly representative of patients receiving low-dose aspirin treatment who had undergone PCI with DES 11 months earlier and were due to stop clopidogrel at 1 year. |
| Selection of the non-exposed cohort | No concurrent control group.
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| Ascertainment of exposure | Secure record (e.g. surgical records) . | |
| Demonstration that outcome of interest was not present at start of study | Demonstration that outcome of interest was not present at start of study. | |
| Comparability bias | Comparability of cohorts on the basis of the design or analysis | The study controlled for cessation of clopidogrel. |
| Outcome bias | Assessment of outcome | Assessment of outcome by record linkage. |
| Was follow-up long enough for outcomes to occur
|
Follow-up was not long enough for outcomes to occur. | |
| Adequacy of follow-up of cohorts | Subjects lost to follow-up unlikely to introduce bias – small number lost (13%). | |
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