A screening method to spot biomarkers that may warn of serious events in a chronic disease - illustrated by cardiological CLARICOR trial data.

OBJECTIVES: To develop a crude screening method for detecting biomarkers which frequently exhibit a rise (or fall) in level prior to a serious event (e.g. a stroke) in patients with a chronic disease, signalling that the biomarker may have an alarm-raising or prognostic potential. The subsequent assessment of the marker's clinical utility requires costly, difficult longitudinal studies. Therefore, initial screening of candidate-biomarkers is desirable. METHODS: The method exploits a cohort of patients with biomarkers measured at entry and with recording of first serious event during follow-up. Copying those individual records onto a common timeline where a specific event occurs on the same day (Day 0) for all patients, the baseline biomarker level, when plotted against the patient's entry time on the revised timeline, will have a positive (negative) regression slope if biomarker levels generally rise (decline) the closer one gets to the event. As an example, we study 1,958 placebo-treated patients with stable coronary artery disease followed for nine years in the CLARICOR trial (NCT00121550), examining 11 newer biomarkers. RESULTS: Rising average serum levels of cardiac troponin T and of N-terminal pro-B-type natriuretic peptide were seen prior to a fatal cardiovascular outcome. C-reactive protein rose prior to non-cardiovascular death. Glomerular filtration rate, seven lipoproteins, and nine newer cardiological biomarkers did not show convincing changes. CONCLUSIONS: For early detection of biomarkers with an alarm-raising potential in chronic diseases, we proposed the described easy procedure. Using only baseline biomarker values and clinical course of participants with coronary heart disease, we identified the same cardiovascular biomarkers as those previously found containing prognostic information using longitudinal or survival analysis.

Pain relief that matters to patients: systematic review of empirical studies assessing the minimum clinically important difference in acute pain.

BACKGROUND: The minimum clinically important difference (MCID) is used to interpret the clinical relevance of results reported by trials and meta-analyses as well as to plan sample sizes in new studies. However, there is a lack of consensus about the size of MCID in acute pain, which is a core symptom affecting patients across many clinical conditions. METHODS: We identified and systematically reviewed empirical studies of MCID in acute pain. We searched PubMed, EMBASE and Cochrane Library, and included prospective studies determining MCID using a patient-reported anchor and a one-dimensional pain scale (e.g. 100 mm visual analogue scale). We summarised results and explored reasons for heterogeneity applying meta-regression, subgroup analyses and individual patient data meta-analyses. RESULTS: We included 37 studies (8479 patients). Thirty-five studies used a mean change approach, i.e. MCID was assessed as the mean difference in pain score among patients who reported a minimum degree of improvement, while seven studies used a threshold approach, i.e. MCID was assessed as the threshold in pain reduction associated with the best accuracy (sensitivity and specificity) for identifying improved patients. Meta-analyses found considerable heterogeneity between studies (absolute MCID: I2 = 93%, relative MCID: I2 = 75%) and results were therefore presented qualitatively, while analyses focused on exploring reasons for heterogeneity. The reported absolute MCID values ranged widely from 8 to 40 mm (standardised to a 100 mm scale) and the relative MCID values from 13% to 85%. From analyses of individual patient data (seven studies, 918 patients), we found baseline pain strongly associated with absolute, but not relative, MCID as patients with higher baseline pain needed larger pain reduction to perceive relief. Subgroup analyses showed that the definition of improved patients (one or several categories improvement or meaningful change) and the design of studies (single or multiple measurements) also influenced MCID values. CONCLUSIONS: The MCID in acute pain varied greatly between studies and was influenced by baseline pain, definitions of improved patients and study design. MCID is context-specific and potentially misguiding if determined, applied or interpreted inappropriately. Explicit and conscientious reflections on the choice of a reference value are required when using MCID to classify research results as clinically important or trivial.

Early-Phase Studies of Biomarkers: What Target Sensitivity and Specificity Values Might Confer Clinical Utility?

BACKGROUND: Many cancer biomarker research studies seek to develop markers that can accurately detect or predict future onset of disease. To design and evaluate these studies, one must specify the levels of accuracy sought. However, justified target levels are rarely available. METHODS: We describe a way to calculate target levels of sensitivity and specificity for a biomarker intended to be applied in a defined clinical context. The calculation requires knowledge of the prevalence or incidence of cases in the clinical population and the ratio of benefit associated with the clinical consequences of a positive biomarker test in cases (true positive) to cost associated with a positive biomarker test in controls (false positive). Guidance is offered on soliciting the cost/benefit ratio. The calculations are based on the longstanding decision theory concept of providing a net benefit on average in the population, and they rely on some assumptions about uniformity of costs and benefits to those tested. RESULTS: Calculations are illustrated with 3 applications: predicting colon cancer recurrence in stage 1 patients; predicting interval breast cancer (between mammography screenings); and screening for ovarian cancer. CONCLUSIONS: It is feasible to specify target levels of biomarker performance that enable evaluation of the potential clinical impact of biomarkers in early-phase studies. Nevertheless, biomarkers meeting the criteria should still be tested rigorously in studies that measure the actual impact on patient outcomes of using the biomarker to make clinical decisions.

The matching quality of experimental and control interventions in blinded pharmacological randomised clinical trials: a methodological systematic review.

BACKGROUND: Blinding is a pivotal method to avoid bias in randomised clinical trials. In blinded drug trials, experimental and control interventions are often designed to be matched, i.e. to appear indistinguishable. It is unknown how often matching procedures are inadequate, so we decided to systematically identify and analyse studies of matching quality in drug trials. Our primary objective was to assess the proportion of studies that concluded that the matching was inadequate; our secondary objective was to describe mechanisms for inadequate matching. METHODS: Systematic review. We searched PubMed, Google Scholar and Web of Science Citation Index for studies that assessed whether supposedly indistinguishable interventions (experimental and control) in randomized clinical drug trials could be distinguished based on physical properties (e.g. appearance or smell). Two persons decided on study eligibility and extracted data independently. Our primary analysis was based on the conclusions of each study. In supportive analyses, we defined a low and a high threshold for inadequate matching. We summarised results qualitatively. RESULTS: We included studies of 36 trials, of which 28 (78%) were published before 1977. The studies differed considerably with regard to design, methodology and analysis. Sixteen of the 36 studies (44%) concluded inadequate matching. When we adapted high or low thresholds for inadequate matching, the number of trials with inadequate matching was reduced to 12 (33%) or increased to 26 (72%). Inadequate matching was concluded in 7 of 22 trials (32%) based on a defined cohort of trials. Inadequate matching was concluded in 9 of 14 trials (64%) which were not based on a trial cohort, and therefore at a higher risk of publication bias. The proportion of inadequate matching did not seem to depend on publication year. Typical mechanisms of inadequate matching were differences in taste or colour. CONCLUSION: We identified matching quality studies of 36 randomized clinical drug trials. Sixteen of the 36 studies (44%) concluded inadequate matching. Few studies of matching quality in contemporary trials have been published, but show similar results as found for older trials. Inadequate matching in drug trials may be more prevalent than commonly believed.

Agreement between public register and adjudication committee outcome in a cardiovascular randomized clinical trial.

UNLABELLED: The objective of this study is to describe the agreement between randomized trial outcome assessment by committee and outcomes entirely identified through public registers. METHODS: In the CLARICOR trial, 4,372 patients with stable coronary heart disease received a short course of clarithromycin versus placebo and were followed up for 2.6 years. The pertinent hospital records and death certificates had originally been evaluated by the adjudication committee using common definitions of outcomes mapped into a 6-category list. We now mechanically converted the International Classification of Diseases-coded diagnoses of the public registries into the same categories. After cross-tabulation of the committee diagnoses with National Patient Register diagnoses and Register of Causes of Death, we calculate agreement and compare the estimated intervention effects of the 2 data sets. RESULTS: With public register data, the protocol-specified categories were slightly more frequent. Overall agreement was 74% for hospital discharges and 60% for cause of death, but the intervention effect, expressed as a hazard ratio, stayed within 4% of the value originally obtained with the adjudication committee (P ≥ .35). CONCLUSIONS: Our results show a modest agreement between formal adjudication and outcomes deducible from public registers. However, the estimated intervention effect did not differ noticeably between the 2 data sources. If studies on a wide range of public registers confirm these findings, register outcomes may be considered as a replacement for adjudication committees.

A note on the evaluation of novel biomarkers: do not rely on integrated discrimination improvement and net reclassification index.

The 'integrated discrimination improvement' (IDI) and the 'net reclassification index' (NRI) are statistics proposed as measures of the incremental prognostic impact that a new biomarker will have when added to an existing prediction model for a binary outcome. By design, both measures were meant to be intuitively appropriate, and the IDI and NRI formulae do look intuitively plausible. Both have become increasingly popular. We shall argue, however, that their use is not always safe. If IDI and NRI are used to measure gain in prediction performance, then poorly calibrated models may appear advantageous, and in a simulation study, even the model that actually generates the data (and hence is the best possible model) can be improved on without adding measured information. We illustrate these shortcomings in actual cancer data as well as by Monte Carlo simulations. In these examples, we contrast IDI and NRI with the area under ROC and the Brier score. Unlike IDI and NRI, these traditional measures have the characteristic that prognostic performance cannot be accidentally or deliberately inflated.

Osteoprotegerin independently predicts mortality in patients with stable coronary artery disease: the CLARICOR trial.

OBJECTIVES: To elucidate the prognostic power of serum osteoprotegerin (OPG) in patients with stable coronary artery disease (CAD). METHODS: Serum OPG levels were measured in the CLARICOR trial cohort of 4063 patients with stable CAD on blood samples drawn at randomization. The follow-up was 2.6 years for detailed cardiovascular events and 6 years for all-cause mortality. RESULTS: OPG levels were significantly increased in non-survivors (21%) compared to survivors (median [quartiles] 2092 ng/L [1636; 2800] compared to 1695 ng/L [1322; 2193, p < 0.0001]). The 2.6-year follow-up showed that OPG adds to the prediction of both cardiovascular and all-cause mortality in combination with clinical risk factors (HR [one log10 unit increase] 6.1 [95% CI 2.4-15.6, p = 0.0001]) and HR 6.5 [95% CI 3.4-12.5, p < 0.0001], respectively). Similar, in the 6-year follow-up, OPG was found to be a strong predictor for all-cause mortality. Importantly, OPG remained an independent predictor of mortality even after adjustment for both clinical and conventional cardiovascular risk markers (HR 2.5 [95% CI 1.6-3.9, p < 0.0001]). CONCLUSIONS: Serum OPG has a long-lasting independent predictive power as to all-cause mortality and cardiovascular death in patients with stable CAD.

Observer bias in randomized clinical trials with measurement scale outcomes: a systematic review of trials with both blinded and nonblinded assessors.

BACKGROUND: Clinical trials are commonly done without blinded outcome assessors despite the risk of bias. We wanted to evaluate the effect of nonblinded outcome assessment on estimated effects in randomized clinical trials with outcomes that involved subjective measurement scales. METHODS: We conducted a systematic review of randomized clinical trials with both blinded and nonblinded assessment of the same measurement scale outcome. We searched PubMed, EMBASE, PsycINFO, CINAHL, Cochrane Central Register of Controlled Trials, HighWire Press and Google Scholar for relevant studies. Two investigators agreed on the inclusion of trials and the outcome scale. For each trial, we calculated the difference in effect size (i.e., standardized mean difference between nonblinded and blinded assessments). A difference in effect size of less than 0 suggested that nonblinded assessors generated more optimistic estimates of effect. We pooled the differences in effect size using inverse variance random-effects meta-analysis and used metaregression to identify potential reasons for variation. RESULTS: We included 24 trials in our review. The main meta-analysis included 16 trials (involving 2854 patients) with subjective outcomes. The estimated treatment effect was more beneficial when based on nonblinded assessors (pooled difference in effect size -0.23 [95% confidence interval (CI) -0.40 to -0.06]). In relative terms, nonblinded assessors exaggerated the pooled effect size by 68% (95% CI 14% to 230%). Heterogeneity was moderate (I(2) = 46%, p = 0.02) and unexplained by metaregression. INTERPRETATION: We provide empirical evidence for observer bias in randomized clinical trials with subjective measurement scale outcomes. A failure to blind assessors of outcomes in such trials results in a high risk of substantial bias.

Excess sudden cardiac deaths after short-term clarithromycin administration in the CLARICOR trial: why is this so, and why are statins protective?

OBJECTIVES: To elucidate potential mechanisms for the clarithromycin-induced excess mortality observed in the CLARICOR trial during 2.6 year follow-up of patients with stable coronary artery disease. METHODS: Cox analyses using out-of-hospital death as a proxy for sudden death compared to in-hospital (nonsudden) death. RESULT: In 100 of 189 (53%) cardiovascular (CV) deaths in which it was possible to examine the question, there was a strong association between place of death and the classification of CV death as sudden or not-sudden. The excess mortality in the clarithromycin group was confined to sudden CV death in patients not on statins at trial entry (HR: 2.61, 95% CI: 1.69-4.05, p < 0.0005). Other categories of deaths showed no marked drug-placebo difference. CONCLUSIONS: Short-term clarithromycin administration was significantly associated with increased risk of sudden CV death in stable coronary heart disease patients not using statins.

High-sensitivity C-reactive protein and N-terminal pro-B-type natriuretic peptide in patients with stable coronary artery disease: a prognostic study within the CLARICOR trial.

BACKGROUND: Patients with stable coronary artery disease (CAD) have a poor prognosis. The aim of the study was to evaluate the extent to which serum high-sensitivity C-reactive protein (hs-CRP) and N-terminal pro-B-type natriuretic peptide (NT-proBNP) measurement alone or together could be prognostic biomarkers in patients with stable CAD. MATERIALS AND METHODS: During the 2.6-year follow-up period 270 patients among the 4264 patients with stable CAD in the CLARICOR trial suffered myocardial infarction (MI) and 377 died (187 cardiovascular deaths (CVD)). RESULTS: Serum NT-proBNP was significantly associated with MI (hazard ratio (HR), 1. 65 (refers to a 2.72 fold increase in serum level, p = 0.0005), CVD (HR, 2.42, p < 0.0005) and non-CVD (HR, 1.79, p < 0.0005). When correcting for hs-CRP, NT-proBNP was still significantly associated with MI (HR, 1.63, p = 0.0005), CVD (HR, 2.36, p < 0.0005) and non-CVD (HR, 1.66, p < 0.0005). Serum hs-CRP was compared to NT-proBNP less associated with MI (HR, 1.20, p = 0.001), CVD (HR, 1.39, p < 0.0005) and non-CVD (HR, 1.67, p < 0.0005). When corrected for NT-proBNP, hs-CRP was only associated with non-CVD (HR, 1.51, p < 0.0005). When adjusting for cardiovascular risk factors hs-CRP predicted non-CVD (HR, 1.46) and all-cause death (HR, 1.24) and NT-proBNP predicted MI (HR, 1.50), CVD (HR, 1.98), non-CVD (HR, 1.39), and all-cause death (HR, 1.62)(p < 0.0005 for all). CONCLUSION: Increased serum NT-proBNP was a stronger predictor of MI, cardiovascular death and non-cardiovascular death than hs-CRP in patients with stable CAD. Once NT-proBNP was taken into account, hs-CRP did not improve predictions.

Trajectories in severe persistent pain after groin hernia repair: a retrospective analysis.

OBJECTIVES: Severe persistent post-surgical pain (PPSP) remains a significant healthcare problem. In the third most common surgical procedure in the U.K., groin hernia repair, including 85,000 surgeries, estimated 1,500-3,000 patients will annually develop severe PPSP. While the trajectory of PPSP is generally considered a continuation of the acute post-surgery pain, recent data suggest the condition may develop with a delayed onset. This study evaluated pain-trajectories in a consecutive cohort referred from groin hernia repair-surgeons to a tertiary PPSP-center. Potential explanatory variables based on individual psychometric, sensory, and surgical profiles were analyzed. METHODS: Patients completed graphs on pain trajectories and questionnaires on neuropathic pain, pain-related functional assessments, and psychometrics. Surgical records and quantitative sensory testing profiles were obtained. Pain trajectories were normalized, and pre- and post-surgical segments were analyzed by a normalized area-under-the-curve (AUC) technique. Principal component analysis (PCA) was applied to the explanatory variables. Significant PCA-components were further examined using multiple logistic regression models. RESULTS: In 95 patients, the AUC identified groups of post-surgical pain trajectories (p<0.0001): group I (n=48), acute high-intensity pain progressing to PPSP; group II (n=28), delayed onset of PPSP; group III (n=7), repeat-surgery gradually inducing PPSP. Data from groups IV (n=3) and V (n=9) were not included in the statistical analysis due to small sample size and data heterogeneity, respectively. The PCA/logistic analyses indicated that neuropathic pain scores, composite pain scores, and pain-related functional assessments were explanatory variables for groups I and II. CONCLUSIONS: Pain trajectories in PPSP after groin hernia repair are heterogeneous but can be classified into meaningful groups. Examination of pain trajectories, mirroring the transition from acute to severe persistent post-surgical pain, has the potential of uncovering clinically relevant pathophysiological mechanisms.

Statin treatment prevents increased cardiovascular and all-cause mortality associated with clarithromycin in patients with stable coronary heart disease.

In the CLARICOR trial, significantly increased cardiovascular (CV) and all-cause mortality in stable patients with coronary heart disease were observed after a short course of clarithromycin. We report on the impact of statin treatment at entry on the CV and all-cause mortality. The multicenter CLARICOR trial randomized patients to oral clarithromycin (500 mg daily; n = 2172) versus matching placebo (daily; n = 2201) for 2 weeks. Patients were followed through public databases. In the 41% patients on statin treatment at entry, no significant effect of clarithromycin was observed on CV (hazard ratio [HR], 0.68, 95% confidence interval [CI], 0.38-1.22; P = 0.20) or all-cause mortality (HR, 1.08; 95% CI, 0.71-1.65; P = 0.72) at 2.6-year follow up. In the patients not on statin treatment at entry, clarithromycin was associated with a significant increase in CV (HR, 1.90; 95% CI, 1.34-2.67; P = 0.0003; statin-clarithromycin interaction P = 0.0029) and all-cause mortality (HR, 1.33; 95% CI, 1.05-1.67; P = 0.016; statin-clarithromycin interaction P = 0.41). Multivariate analysis and 6-year follow up confirmed these results. Concomitant statin treatment in stable patients with coronary heart disease abrogated the observed increased CV mortality associated with 2 weeks of clarithromycin.

Prognosis and Reclassification by YKL-40 in Stable Coronary Artery Disease.

Background The inflammatory biomarker YKL-40 has previously been studied as a potential risk marker in cardiovascular disease. We aimed to assess the prognostic reclassification potential of serum YKL-40 in patients with stable coronary artery disease. Methods and Results The main study population was the placebo group of the CLARICOR (Effect of Clarithromycin on Mortality and Morbidity in Patients With Ischemic Heart Disease) trial. The primary outcome was a composite of acute myocardial infarction, unstable angina pectoris, cerebrovascular disease, and all-cause mortality. We used Cox proportional hazards regression models adjusted for C-reactive protein level and baseline cardiovascular risk factors. Improvement in prediction by adding serum YKL-40 to the risk factors was calculated using the Cox-Breslow method and c-statistic. A total of 2200 patients were randomized to placebo, with a follow-up duration of 10 years. YKL-40 was associated with an increased risk of the composite outcome (hazard ratio per unit increase in (YKL-40) 1.13, 95% CI 1.03-1.24, P=0.013) and all-cause mortality (hazard ratio 1.32, 95% CI 1.17-1.49, P<0.0001). Considering whether a composite-outcome event was more likely to have, or not have, occurred to date, we found 68.4% of such predictions to be correct when based on the standard predictors, and 68.5% when serum YKL-40 was added as a predictor. Equivalent results were obtained with c-statistics. Conclusions Higher serum YKL-40 was independently associated with an increased risk of adverse cardiovascular outcomes and mortality. Addition of YKL-40 did not improve risk prediction in patients with stable coronary artery disease. Clinical Trial Registration URL: https://www.clinicaltrials.gov/. Unique identifier: NCT00121550.

Serum osteoprotegerin as a long-term predictor for patients with stable coronary artery disease and its association with diabetes and statin treatment: A CLARICOR trial 10-year follow-up substudy.

BACKGROUND AND AIMS: Elevated circulating levels of osteoprotegerin (OPG) are known to add to the prediction of cardiovascular mortality. Our objective was to clarify the long-term risk associated with serum OPG and the possible influence of diabetes and statins on OPG levels in patients with stable coronary artery disease (CAD). METHODS: We assessed the placebo-treated group (n = 1998) from the CLARICOR trial (NCT00121550), a cohort with stable CAD. At entry, 15% of the participants had diabetes and 41% received statins. Serum OPG levels were measured in blood drawn at randomization. Participants were followed through public registers for 10 years. RESULTS: OPG levels correlated positively with diabetes status, age, CRP and female sex, but negatively with the use of statins. CAD participants with diabetes had significantly elevated serum OPG levels compared to participants without diabetes, p < 0.0001. The participants without diabetes treated with statins presented with significantly lower serum OPG levels than the corresponding non-statin-users (p < 0.0001). However, statin use showed no association with OPG levels in the participants with diabetes. High OPG levels at entry showed long-term associations with all-cause mortality and cardiovascular events (hazard ratio associated with factor 10 OPG increase 15.9 (95% CI 11.0-22.9) and 6.38 (4.60-8.90), p = 0.0001, even after adjustment for standard predictors (3.16 (1.90-5.25) and 2.29 (1.53-3.44), p < 0.0001). CONCLUSIONS: Circulating OPG holds long-term independent predictive ability for all-cause mortality and cardiovascular events in CAD participants. OPG levels were associated with diabetes, age, and female sex and statin treatment was associated with lower OPG levels in the absence of diabetes.

Prognostic value of 12 novel cardiological biomarkers in stable coronary artery disease. A 10-year follow-up of the placebo group of the Copenhagen CLARICOR trial.

OBJECTIVE: To assess if 12 novel circulating biomarkers, when added to 'standard predictors' available in general practice, could improve the 10-year prediction of cardiovascular events and mortality in patients with stable coronary heart disease. DESIGN: The patients participated as placebo receiving patients in the randomised clarithromycin for patients with stable coronary artery disease (CLARICOR) trial at a random time in their disease trajectory. SETTING: Five Copenhagen University cardiology departments and a coordinating centre. PARTICIPANTS: 1998 participants with stable coronary artery disease. OUTCOMES: Death and composite of myocardial infarction, unstable angina pectoris, cerebrovascular disease and death. RESULTS: When only 'standard predictors' were included, 83.4% of all-cause death predictions and 68.4% of composite outcome predictions were correct. Log(calprotectin) and log(cathepsin-S) were not associated (p≥0.01) with the outcomes, not even as single predictors. Adding the remaining 10 biomarkers (high-sensitive assay cardiac troponin T; neutrophil gelatinase-associated lipocalin; osteoprotegerin; N-terminal pro-B-type natriuretic peptide; tumour necrosis factor receptor 1 and 2; pregnancy-associated plasma protein A; endostatin; YKL40; cathepsin-B), which were all individually significantly associated with the prediction of the two outcomes, increased the figures to 84.7% and 69.7%. CONCLUSION: When 'standard predictors' routinely available in general practices are used for risk assessment in consecutively sampled patients with stable coronary artery disease, the addition of 10 novel biomarkers to the prediction model improved the correct prediction of all-cause death and the composite outcome by <1.5%. TRIAL REGISTRATION NUMBER: NCT00121550.

Power estimations for non-primary outcomes in randomised clinical trials.

OBJECTIVE AND METHODS: It is rare that trialists report power estimations of non-primary outcomes. In the present article, we will describe how to define a valid hierarchy of outcomes in a randomised clinical trial, to limit problems with Type I and Type II errors, using considerations on the clinical relevance of the outcomes and power estimations. CONCLUSION: Power estimations of non-primary outcomes may guide trialists in classifying non-primary outcomes as secondary or exploratory. The power estimations are simple and if they are used systematically, more appropriate outcome hierarchies can be defined, and trial results will become more interpretable.

Circulating endostatin as a risk factor for cardiovascular events in patients with stable coronary heart disease: A CLARICOR trial sub-study.

BACKGROUND AND AIMS: Raised levels of serum endostatin, a biologically active fragment of collagen XVIII, have been observed in patients with ischemic heart disease but association with incident cardiovascular events in patients with stable coronary heart disease is uncertain. METHODS: The CLARICOR-trial is a randomized, placebo-controlled trial of stable coronary heart disease patients evaluating 14-day treatment with clarithromycin. The primary outcome was a composite of acute myocardial infarction, unstable angina pectoris, cerebrovascular disease or all-cause mortality. In the present sub-study using 10-year follow-up data, we investigated associations between serum endostatin at entry (randomization) and the composite outcome and its components during follow-up. The placebo group was used as discovery sample (1204 events, n = 1998) and the clarithromycin-treated group as replication sample (1220 events, n = 1979). RESULTS: In Cox regression models adjusting for cardiovascular risk factors, glomerular filtration rate, and current pharmacological treatment, higher serum endostatin was associated with an increased risk of the composite outcome in the discovery sample (hazard ratio per standard deviation increase 1.11, 95% CI 1.03-1.19, p = 0.004), but slightly weaker and not statistically significant in the replication sample (hazard ratio 1.06, 95% CI 1.00-1.14, p = 0.06). In contrast, strong and consistent associations were found between endostatin and cardiovascular and all-cause mortality in all multivariable models and sub-samples. Addition of endostatin to a model with established cardiovascular risk factors provided no substantial improvement of risk prediction (<1%). CONCLUSIONS: Raised levels of serum endostatin might be associated with cardiovascular events in patients with stable coronary heart disease. The clinical utility of endostatin measurements remains to be established.

Clarithromycin for 2 weeks for stable coronary heart disease: 6-year follow-up of the CLARICOR randomized trial and updated meta-analysis of antibiotics for coronary heart disease.

OBJECTIVES: We have reported increased 2.6-year mortality in clarithromycin- versus placebo-exposed stable coronary heart disease patients, but meta-analysis of randomized trials in coronary heart disease patients showed no significant effect of antibiotics on mortality. Here we report the 6-year mortality of clarithromycin- versus placebo-exposed patients and updated meta-analyses. METHODS: Centrally randomized, placebo controlled multicenter trial. All parties were blinded. Analyses were by intention to treat. Meta-analyses followed the Cochrane Collaboration methodology. RESULTS: We randomized 4,372 patients with stable coronary heart disease to clarithromycin 500 mg (n = 2,172) or placebo (n = 2,200) once daily for 2 weeks. Mortality was followed through public register. Nine hundred and twenty-three patients (21.1%) died. Six-year mortality was significantly higher in the clarithromycin group (hazard ratio 1.21, 95% confidence interval 1.06-1.38). Adjustment for entry characteristics (sex, age, prior myocardial infarction, center, and smoking) did not change the results (1.18, 1.04-1.35). Addition of our data to that of other randomized trials on antibiotics for patients with coronary heart disease versus placebo/no intervention (17 trials, 25,271 patients, 1,877 deaths) showed a significantly increased relative risk of death from antibiotics of 1.10 (1.01-1.20) without heterogeneity. CONCLUSIONS: Our results stress the necessity to consider carefully the strength of the indication before administering antibiotics to patients with coronary heart disease.