1 Medical Research Institute of New Zealand, Wellington
2 Wellington School of Medicine & Health Sciences, Wellington, New
Zealand
Correspondence to: Professor Richard Beasley E-mail: richard.beasley{at}mrinz.ac.nz
| SUMMARY |
|---|
|
|
|---|
Design: Systematic review and meta-analysis of randomized double-blind clinical trials of celecoxib of at least 6 weeks' duration and presented data on serious cardiovascular thromboembolic events. Data sources included six bibliographic databases, the relevant files of the United States Food and Drug Administration, and pharmaceutical company websites.
Main outcome measures: Pooled fixed effects estimates of the odds ratios for risk of cardiovascular events with celecoxib compared with comparator treatment were calculated using the inverse variance weight method. The main outcome measure was myocardial infarction.
Results: Four placebo-controlled trials with 4422 patients were included in the primary meta-analysis comparing celecoxib with placebo. The odds ratio of myocardial infarction with celecoxib compared to placebo was 2.26 (95%confidence interval 1.0 to 5.1). For composite cardiovascular events [odd ratio 1.38 (95% CI 0.91 to 2.10)], cardiovascular deaths [OR 1.06 (95% CI 0.38 to 2.95)] and stroke [OR 1.0(95% CI 0.51 to 1.84)] there was no significant increase in risk with celecoxib. The secondary meta-analysis which included a total of six studies (with placebo, diclofenac, ibuprofen, and paracetamol as comparators) of 12 780 patients, showed similar findings with a significant increased risk with celecoxib for myocardial infarction [OR 1.88 (95% CI 1.15 to 3.08)] but not other outcome measures.
Conclusion: The available data indicate an increased risk of myocardial infarction with celecoxib therapy, consistent with a class effect for COX-2 specific inhibitors.
| INTRODUCTION |
|---|
|
|
|---|
In an attempt to clarify this issue we have undertaken a systematic review and meta-analysis of double-blind, randomized, controlled studies of celecoxib that presented data on serious cardiovascular events. The primary meta-analysis included clinical trials that compared celecoxib with placebo, whereas in the secondary meta-analysis the placebo-controlled trials were analysed together with controlled trials that used non-steroidal anti-inflammatory drugs (NSAIDs) or paracetamol as comparator treatments.
| METHODS |
|---|
|
|
|---|
|
Inclusion criteria
To be included in the systematic review, studies had to be randomized,
double-blind, controlled clinical trials of at least 6 weeks' duration and
report serious cardiovascular thromboembolic events.
The primary meta-analysis included clinical trials that compared celecoxib with placebo. A secondary meta-analysis included trials that compared celecoxib with placebo, paracetamol or an NSAID.
Outcome measures
The primary outcome variable was myocardial infarction (fatal or
non-fatal). The secondary outcome variables were fatal or non-fatal
cerebrovascular events (thrombotic or haemorrhagic), cardiovascular mortality,
and the composite outcome of serious cardiovascular thromboembolic events.
Criteria for composite cardiovascular thromboembolic events were derived from
the publication of the cardiovascular events from the CLASS
trial.12 The
criteria included myocardial infarction, cerebrovascular events,
cardiovascular death, unstable angina or peripheral vascular event (arterial
or venous). Two reviewers extracted the cardiovascular event data using a
standardized form. Completed data forms were then checked by a third
reviewer.
Analysis
The number of cardiovascular thromboembolic events in the celecoxib and
control groups was stated. The pooled fixed effects estimates of the odds
ratio for risk of cardiovascular events with the use of the active treatment
were calculated by standard methods using the inverse variance weighting
method.13 For zero
cell counts, the standard method of adding 0.5 to each cell count was used.
The I-squared inconsistency statistic was also calculated. The I-squared
statistic is the percentage of total variation across studies due to
heterogeneity.14
These methods assume a constant hazard ratio over time, that is the ratio of
the myocardial infarction rate of one treatment compared with the other is the
same at all time points. A secondary analysis was carried out by calculating
the pooled absolute difference for the outcome variable of those studies which
had at least one
event.13
Study characteristics
The characteristics of the studies were reviewed to determine whether they
were designed or powered to identify the risk of cardiovascular events with
celecoxib therapy. With regard to design, the studies were reviewed to
determine whether the assessment of cardiovascular risk was stated as one of
the objectives, subjects with cardiovascular disease were included, criteria
were defined for diagnosing a cardiovascular event, an electrocardiogram was
routinely undertaken both pre- and post-treatment, and whether a blinded
external board reviewed the cardiovascular events.
Power calculation
A power calculation was undertaken to determine whether the individual
studies had an adequate power to identify an increased risk of myocardial
infarction with celecoxib therapy. For a study to have 80% power, at a type I
error rate of 5%, to detect the difference between an end point occurring 0.4%
of the time and 0.8% of the time, there would need to be around 5850 subjects
in each arm of a two arm trial. This calculation assumes a simple binomial
test for a difference in proportions carried out once at study termination,
rather than a more sophisticated survival analysis that might be used in such
a trial. The choice of 0.4% for endpoint occurrence was based on this crude
proportion from the four placebo controlled trials.
| RESULTS |
|---|
|
|
|---|
The characteristics of the studies included in the meta-analyses are shown in Table 1. Treatment was for a wide range of medical conditions including rheumatoid arthritis, osteoarthritis, Alzheimer's disease, and the prevention of colorectal adenoma in high risk subjects. The duration of treatment ranged from 6-161 weeks. The doses of celecoxib studied were 200, 400 and 800 mg/day.
|
Two of the studies have not yet been published in peer-reviewed journals and the data for these trials were sourced from the internet.15,17,19,20 Data from the CLASS trial have been published in several papers and FDA internet files.5,12,21,22 For our meta-analysis, the findings as documented in the White et al. publication12 were used, as it specifically reported the cardiovascular events. Two web-based publications presented data from the Alzheimer's disease trial;15,20 for our meta-analysis, the findings from the Pfizer document were used as this report presented the most detailed database.15
Study quality
The six studies included in the meta-analyses were neither powered nor
specifically designed to determine the risk of cardiovascular thromboembolic
events associated with celecoxib therapy. Specifically, there were no studies
that had an adequate sample size to determine a twofold increased risk of
myocardial infarction with celecoxib therapy. In none of the studies was it
documented that there was a systematic surveillance for cardiovascular events
such as an ECG taken both pre- and post-treatment, and only one study defined
the criteria for the diagnosis of cardiovascular
events.6 A minority
of studies reported that a blinded external board reviewed the cardiovascular
data.
There were discrepancies in the reporting of cardiovascular events between the various publications of the CLASS trial. For example, no cardiovascular deaths were reported in the initial publication,5 whereas there were 13 cardiovascular deaths in the FDA report22 (five on celecoxib, eight on an NSAID) and 20 in the White et al. publication12 (10 in each treatment group). There were also variations in the number of adverse events and the way such events were classified in the two web-based reports of the Alzheimer's study.15,20 The document placed on the internet by Pfizer15 reported the incidence of cerebrovascular disorder as five events in three patients in the placebo group, compared to eight events in six patients in the celecoxib group. In contrast, on the FDA website20 the incidence of any cerebrovascular event was three in the placebo group and seven in the celecoxib group. In the Solomon et al. study6 and the PreSAP trial17,19 the causes of the cardiovascular deaths in the different treatment groups were not stated. As a result, it was not possible to determine the number of myocardial infarctions or cerebrovascular events that were fatal, and as a result, only the reported non-fatal events could be included in our meta-analysis for myocardial infarction and cerebrovascular event.
Primary meta-analysis
Myocardial infarction
In the three studies which reported myocardial infarction data, there were
29 myocardial infarctions in the 2574 subjects on celecoxib (1.13%), and six
myocardial infarctions in the 1447 subjects in the placebo group (0.41%). The
odds ratio for a myocardial infarction with celecoxib was 2.26 (95% CI 1.0 to
5.1) (Figure 2).
|
Cerebrovascular events
There were 24 cerebrovascular events in the 2775 subjects (0.86%) of the
celecoxib group compared to 13 cerebrovascular events in the placebo group of
1647 subjects (0.79%). The odds ratio was 1.0 (95% CI 0.51 to 1.84).
Cardiovascular death
In the three studies that reported the number of deaths from cardiovascular
causes, there were 16 cardiovascular deaths in the 2574 subjects taking
celecoxib (0.62%) and seven cardiovascular deaths in the 1447 subjects on
placebo (0.48%). The odds ratio for cardiovascular death was 1.06 (95% CI 0.38
to 2.95).
Composite cardiovascular events
There were 79 composite cardiovascular events in the 2775 subjects in the
celecoxib group (2.85%) and 30 composite cardiovascular events in the 1647
subjects taking placebo (1.82%). The odds ratio for a composite cardiovascular
event was 1.38 (95% CI 0.91 to
2.10).
|
Secondary meta-analysis
Myocardial infarction
In the five studies that reported myocardial infarction data, there were 55
myocardial infarctions in the 6658 subjects (0.83%) on celecoxib compared to
21 myocardial infarctions in the 5522 subjects receiving control treatment
(0.38%). The odds ratio for the risk of a myocardial infarction with celecoxib
treatment was 1.88 (95% CI 1.15 to 3.08)
(Figure 3).
|
Cerebrovascular events
There were 28 cerebrovascular events in the 6859 subjects (0.41%) on
celecoxib and 27 in 5921 subjects (0.46%) receiving the control treatment. The
odds ratio for a cerebrovascular event with celecoxib treatment was 0.73 (95%
CI 0.42 to 1.26).
Cardiovascular death
In the five studies that reported the number of deaths from cardiovascular
causes, there were 26 cardiovascular deaths in 6561 subjects taking celecoxib
(0.40%) and 17 cardiovascular deaths in the 5428 subjects on control treatment
(0.31%). The odds ratio for the risk of a cardiovascular death with celecoxib
therapy was 1.02 (95% CI 0.52 to 1.99).
Composite cardiovascular events
There were 134 composite cardiovascular events in 6859 subjects (1.95%) on
celecoxib treatment and 81 in 5921 subjects (1.37%) on control treatments. The
odds ratio for the risk of a composite cardiovascular event with celecoxib
therapy was 1.22 (95% CI 0.92 to 1.62).
| DISCUSSION |
|---|
|
|
|---|
Strengths and weaknesses of the study
There are a number of methodological issues relevant to the interpretation
of the findings. The first is whether all available studies were included in
the meta-analysis. Despite the recognized difficulties encountered with
publication
bias, and the
requirement to access multiple company and FDA
websites,23 we are
confident that we have identified all eligible studies of celecoxib. There was
a requirement for studies to present data on at least one of the three major
serious cardiovascular outcome measures, namely myocardial infarction,
cardiovascular death or cerebrovascular event. We considered that an inability
to report the presence or absence of these outcome measures indicated that the
study was neither designed nor capable of identifying the occurrence of
serious cardiovascular thromboembolic events.
|
Another issue was the decision to undertake a primary meta-analysis restricted to studies which compared celecoxib with placebo. While this reduced the number of eligible studies, it did avoid the potential difficulty of interpreting studies in which comparisons were made with treatments such as NSAIDs which may influence cardiovascular risk.
It was not possible to investigate the potential effect that total daily dose, frequency of dosing and duration of treatment might have in determining cardiovascular risk due to the small number of trials that met the inclusion criteria. In terms of the duration of treatment all but two studies were of at least 1 year's duration. These two studies were of only 6 weeks' duration, were the smallest and of poorest quality, and added only two cardiovascular events to the combined meta-analyses. Inclusion of these studies reduced the magnitude of the risk of myocardial infarction associated with celecoxib therapy.
Trials over 6 weeks' duration were chosen to exclude trials where a single dose was administered or the duration of treatment was too short to expect there to be any long-term sequelae.
Strengths and weaknesses of included studies
The celecoxib clinical research programme was primarily designed to
determine its efficacy and risk of gastrointestinal side effects. For these
reasons we reviewed the characteristics of the studies to determine whether
they were powered or designed to identify serious cardiovascular risks
associated with medication use. This review identified that none of the
studies was adequately powered to determine whether celecoxib increased the
risk of myocardial infarction by twofold and that no clinical trial was
primarily undertaken to assess cardiovascular risk. However, in contrast to
the major clinical trials with
rofecoxib24,25
and lumiracoxib,26
patients were not excluded due to previous cardiovascular disease, which
allowed a more accurate determination of the risk in the population likely to
receive this drug.
Our review identified inconsistencies in the reporting of the major cardiovascular events in the CLASS trial. For example, the original publication of the first six months of the CLASS trial did not report any deaths,5 whereas the two subsequent publications which reported the complete 12 months findings stated that there were 20 cardiovascular deaths12 and 13 cardiovascular deaths, respectively.22 It is difficult to conceive how such major differences in events could occur in reports from the same clinical trial, particularly with definite end points such as death. These inconsistencies add to the previous concerns about the reporting of gastrointestinal side-effects from the CLASS trial.27-29 Likewise, there were differences in the reporting of cerebrovascular events between the two web-based publications of the Alzheimer's trial.15,20 The difficulties in undertaking a meta-analysis when there is discordant data and differing classification of major outcomes from publications of the same clinical trial is evident.
Comparison with other COX-2 inhibitors
The use of celecoxib was associated with a 2.26-fold increased risk of
myocardial infarction when compared with placebo, and a 1.88-fold increased
risk of myocardial infarction when compared with all comparator treatment
groups. These risks are similar in magnitude to the 2.24-fold (95% CI 1.24 to
4.02) increased risk of myocardial infarction with rofecoxib reported in a
comparable
meta-analysis.24
Consistent with these meta-analyses, an increased risk of myocardial
infarction has also been observed in studies of the COX-2 inhibitors
parecoxib/valdecoxib.30,31
In contrast to the increased risk of myocardial infarction, our meta-analysis did not identify a corresponding increased risk of a cerebrovascular event. A similar pattern has been seen with rofecoxib,24 but not with parecoxib/valdecoxib.30,31 This finding suggests that the proposed mechanism whereby COX-2 inhibitors increase the cardiovascular risk, by shifting the functional balance of the vasoactive prostenoids,32-34 may preferentially apply to the pathogenesis of myocardial infarction rather than cerebrovascular events. This may be because myocardial infarction is predominantly due to thrombosis within the coronary arteries, whereas two-thirds of cerebrovascular events are due to thromboembolism from sources outside the brain.35
| CONCLUSION |
|---|
|
|
|---|
Contributors SA, PS, MW and RB were involved in the study design. BC, SA, PS and RB undertook the literature review, data collection and systematic review. MW undertook the statistical analysis. BC and RB wrote the manuscript with help from the other authors.
Competing interests No conflict of interest or competing interests are declared for any of the listed authors.
Funding Funding was received from the bequest of the Estate of Beverley Liddington. No pharmaceutical company had any role in the study design, data collection, analysis or interpretation, or in the writing of the report. The corresponding author had final responsibility for the decision to submit for publication.
| REFERENCES |
|---|
|
|
|---|
Related articles in JRSM:
This article has been cited by other articles:
![]() |
M W van der Linden, S van der Bij, P Welsing, E J Kuipers, and R M C Herings The balance between severe cardiovascular and gastrointestinal events among users of selective and non-selective non-steroidal anti-inflammatory drugs Ann Rheum Dis, May 1, 2009; 68(5): 668 - 673. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Kleinert, C. Lange, A. Steup, P. Black, J. Goldberg, and P. Desjardins Single Dose Analgesic Efficacy of Tapentadol in Postsurgical Dental Pain: The Results of a Randomized, Double-Blind, Placebo-Controlled Study Anesth. Analg., December 1, 2008; 107(6): 2048 - 2055. [Abstract] [Full Text] [PDF] |
||||
![]() |
V. F. Panoulas, G. S. Metsios, A. V. Pace, H. John, G. J. Treharne, M. J. Banks, and G. D. Kitas Hypertension in rheumatoid arthritis Rheumatology, September 1, 2008; 47(9): 1286 - 1298. [Abstract] [Full Text] [PDF] |
||||
![]() |
P. I. Sidiropoulos, G. Hatemi, I.-H. Song, J. Avouac, E. Collantes, V. Hamuryudan, M. Herold, T. K. Kvien, H. Mielants, J. M. Mendoza, et al. Evidence-based recommendations for the management of ankylosing spondylitis: systematic literature search of the 3E Initiative in Rheumatology involving a broad panel of experts and practising rheumatologists Rheumatology, March 1, 2008; 47(3): 355 - 361. [Abstract] [Full Text] [PDF] |
||||
![]() |
P A Scott, G H Kingsley, C M Smith, E H Choy, and D L Scott Non-steroidal anti-inflammatory drugs and myocardial infarctions: comparative systematic review of evidence from observational studies and randomised controlled trials Ann Rheum Dis, October 1, 2007; 66(10): 1296 - 1304. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Gamerdinger, A. B. Clement, and C. Behl Cholesterol-Like Effects of Selective Cyclooxygenase Inhibitors and Fibrates on Cellular Membranes and Amyloid-beta Production Mol. Pharmacol., July 1, 2007; 72(1): 141 - 151. [Abstract] [Full Text] [PDF] |
||||
![]() |
K. Brune and D. E. Furst Combining enzyme specificity and tissue selectivity of cyclooxygenase inhibitors: towards better tolerability? Rheumatology, June 1, 2007; 46(6): 911 - 919. [Abstract] [Full Text] [PDF] |
||||
![]() |
I. G. E. Zarraga and E. R. Schwarz Coxibs and Heart Disease: What We Have Learned and What Else We Need to Know J. Am. Coll. Cardiol., January 2, 2007; 49(1): 1 - 14. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. Andersohn, S. Suissa, E. Garbe, S. Solomon, J. Wittes, N. Arber, M. Bertagnolli, E. Hawk, B. Levin, the APC and PreSAP Trial Investigators, et al. Risks and Benefits of Celecoxib to Prevent Colorectal Adenomas N. Engl. J. Med., November 30, 2006; 355(22): 2371 - 2373. [Full Text] [PDF] |
||||
![]() |
P. McGettigan and D. Henry Cardiovascular Risk and Inhibition of Cyclooxygenase: A Systematic Review of the Observational Studies of Selective and Nonselective Inhibitors of Cyclooxygenase 2 JAMA, October 4, 2006; 296(13): 1633 - 1644. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Zhang, E. L. Ding, and Y. Song Adverse Effects of Cyclooxygenase 2 Inhibitors on Renal and Arrhythmia Events: Meta-analysis of Randomized Trials JAMA, October 4, 2006; 296(13): 1619 - 1632. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. B. Dalby, D. N. Frank, A. L. St. Amand, A. M. Bendele, and N. R. Pace Culture-independent analysis of indomethacin-induced alterations in the rat gastrointestinal microbiota. Appl. Envir. Microbiol., October 1, 2006; 72(10): 6707 - 6715. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Chaiamnuay, J. J. Allison, and J. R. Curtis Risks versus benefits of cyclooxygenase-2-selective nonsteroidal antiinflammatory drugs. Am. J. Health Syst. Pharm., October 1, 2006; 63(19): 1837 - 1851. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. Cheung and S. Lowry Celecoxib J R Soc Med, July 1, 2006; 99(7): 336 - 336. [Full Text] [PDF] |
||||
![]() |
P. Dieppe Complicity theory: an explanation for the ;coxib problem'? J R Soc Med, June 1, 2006; 99(6): 273 - 274. [Full Text] [PDF] |
||||
![]() |
M. Weatherall, S. Aldington, B. Caldwell, and R. Beasley Inconsistencies in cardiovascular data from COX-2 inhibitor trials--is it a class effect? J R Soc Med, June 1, 2006; 99(6): 275 - 276. [Full Text] [PDF] |
||||
![]() |
Celecoxib and Cardiovascular Risk Journal Watch Cardiology, March 30, 2006; 2006(330): 3 - 3. [Full Text] |
||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||