Evaluating the effectiveness of combination therapy to prevent COPD exacerbations: the value of NNT analysis

Effect of ivabradine on numbers needed to treat for the prevention of recurrent hospitalizations in heart failure patients

BACKGROUND

Ivabradine, a specific heart rate lowering agent, was shown in the SHIFT study to reduce time to first hospitalization for worsening heart failure (HF) in chronic systolic HF patients and also to reduce recurrent/total hospitalizations over the study interval. We assessed the effects of adding ivabradine in patients with systolic HF on the number needed to treat (NNT) to reduce recurrent hospitalizations.

METHODS

The SHIFT trial included 6505 patients with symptomatic HF (NYHA II-IV), left ventricular ejection fraction ≤35% and heart rate ≥70 bpm in sinus rhythm. Patients were randomized to either ivabradine or placebo in addition to guidelines-based drug therapy. The times to first hospitalization were analyzed using a univariate Cox proportional-hazards model; the associated NNT was calculated using Kaplan-Meier estimates of the time-to-event curves at 1 year in each treatment arm. Recurrent hospitalizations were analyzed using a negative binomial and the estimated annual event rates used to calculate the associated patient-time NNTs respectively.

RESULTS

The estimated NNT (number needed to initiate treatment with ivabradine to prevent one first HF hospitalization within 1 year) was 27 (estimated hazard ratio: 0.75, P < 0.0001). For recurrent HF hospitalizations, one event would be prevented on average per 14 patient-years for any year of follow-up over the course of SHIFT (estimated rate ratio: 0.71, P < 0.0001). A key limitation of this analysis is that it did not account for a relationship between recurrent HF hospitalizations and subsequent mortality.

CONCLUSION

In chronic systolic HF the effect of ivabradine on reducing recurrent HF hospitalizations results in a lower NNT compared to the effect on the time for first hospitalization. The effect of ivabradine on recurrent hospitalizations, in addition to first events, may be a more appropriate measure when considering the impact of a treatment with ivabradine on healthcare resource utilization.

Inhaled corticosteroids in COPD: the clinical evidence

In this article, we focus on the scientific evidence from randomised trials supporting treatment with inhaled corticosteroids (ICS) in chronic obstructive pulmonary disease (COPD), including treatment with combinations of long-acting β-agonist (LABA) bronchodilators and ICS. Our emphasis is on the methodological strengths and limitations that guide the conclusions that may be drawn. The evidence of benefit of ICS and, therefore, of the LABA/ICS combinations in COPD is limited by major methodological problems. From the data reviewed herein, we conclude that there is no survival benefit independent of the effect of long-acting bronchodilation and no effect on FEV1 decline, and that the possible benefit on reducing severe exacerbations is unclear. Our interpretation of the data is that there are substantial adverse effects from the use of ICS in patients with COPD, most notably severe pneumonia resulting in excess deaths. Currently, the most reliable predictor of response to ICS in COPD is the presence of eosinophilic inflammation in the sputum. There is an urgent need for better markers of benefit and risk that can be tested in randomised trials for use in routine specialist practice. Given the overall safety and effectiveness of long-acting bronchodilators in subjects without an asthma component to their COPD, we believe use of such agents without an associated ICS should be favoured.

Mortality in COPD: inevitable or preventable? Insights from the cardiovascular arena

Mortality due to chronic obstructive pulmonary disease continues to rise, whereas mortality rates related to cardiovascular disease appear to be slowing, or even declining. This is due at least in part to more widespread use of preventative therapies that have been shown to reduce cardiovascular mortality, raising the question of whether appropriate use of therapies for chronic obstructive pulmonary disease which potentially reduce mortality could have a similar impact. This article discusses approaches used successfully in managing heart disease and considers whether these can be applied to chronic obstructive pulmonary disease and whether a better understanding of the strongest predictors of mortality in chronic obstructive pulmonary disease is needed. It reviews the role of inhaled corticosteroids, both alone and in combination with long-acting beta(2)-agonists, in individuals with chronic obstructive pulmonary disease, including the role of combination therapy with inhaled corticosteroids/long-acting beta(2)-agonists (budesonide/formoterol or salmeterol/fluticasone propionate) in decreasing exacerbations and improving health status, potentially providing survival benefits in chronic obstructive pulmonary disease. This review also discusses the potential impact of treatments indicated for cardiovascular disease on chronic obstructive pulmonary disease and possible links between the two diseases.

Salmeterol/fluticasone combination in the treatment of COPD

Clinical trials of a combination therapy of an inhaled corticosteroid, fluticasone propionate (FP), with a long-acting β₂-agonist, salmeterol (Sal), have demonstrated a greater improvement in lung function and in quality of life measures after the combination compared with either component of alone. In a subanalysis of the data of the TRISTAN study, Sal/FP reduced exacerbation rates in COPD patients with a baseline FEV₁<50% of predicted. A combination therapy of budesonide and formoterol improved quality of life and FEV₁, and reduced exacerbations better than either component alone. In studies of FP or of Sal/FP in COPD, there was a reduction in all-cause mortality by 25% relative to placebo. Sal/FP has anti-inflammatory effects in COPD airways. FP inhibits markers of systemic inflammation, and it is not known whether Sal/FP has an advantage over FP alone. While long-acting β₂-agonists such as Sal can be recommended for treatment of moderate COPD, addition of inhaled steroid therapy such as FP should be considered in more severe disease.

Tiotropium for the treatment of stable chronic obstructive pulmonary disease: A systematic review with meta-analysis

BACKGROUND

Current guidelines recommend the use of inhaled tiotropium in patients with stable chronic obstructive pulmonary disease (COPD). However, this statement is based on a relatively small number of randomized controlled trials (RCTs) and related systematic reviews. This review was undertaken to incorporate the more recent evidence available about the effectiveness of tiotropium bromide compared with placebo, iptratropium bromide or long-acting beta-agonists (LABAs), for the treatment of stable COPD patients.

DATA SOURCE

Medline, EMBASE, CINAHL, and the Cochrane Controlled Trials Register (to February 2006) were searched to identify all published RCTs. We also searched bibliographies of relevant articles.

RESULTS

Data from 13 RCT (6078 subjects, 80% male) showed that tiotropium reduced COPD-related exacerbations (OR=0.76; 95% CI: 0.68-0.87) and hospital admissions (OR=0.59; 95% CI: 0.47-0.73) compared with placebo. Also, tiotropium showed statistically significant improvement in lung function, including trough, average, and peak FEV(1) and FVC from baseline, compared with placebo and ipratropium. The administration of inhaled tiotropium lead to 30% reduction in COPD-related admissions (OR= 0.67; 95% CI: 0.46-0.98) compared with LABAs. Finally, increases in FEV(1) and FVC from baseline were significantly larger with tiotropium than with LABAs.

CONCLUSIONS

This review clearly supports the beneficial effects of the use of tiotropium in stable moderate-to-severe COPD patients, and increases the evidence in favor of the superiority of tiotropium on LABAs.

Evidence-based dermatology: Number needed to treat and its relation to other risk measures

When discussing treatment options with patients, clinicians often use terms such as "frequently" or "rarely" when referring to potential benefits or possible harms. Quantitative measurements of treatment benefits and harms derived from randomized clinical trials or meta-analysis such as odds ratios or risk reduction are more precise terms, yet physicians and their patients find them difficult to understand and they are not, therefore, commonly used in clinical practice. To overcome the lack of intuitiveness for traditional measures of risk estimates derived from clinical trials, the number needed to treat (NNT) has been widely recommended as a measure of effectiveness, and number needed to harm as a way of describing risk of possible adverse events. NNT is simply the number of patients who, on average, would need to be treated with a proposed intervention to demonstrate one additional gain over the standard comparator intervention. NNT is an absolute measure and it is calculated as the inverse of the absolute risk reduction. In this article we describe the usefulness and limits of the NNT with particular reference to dermatology, and compare NNT with other relative measures such as the relative risk and relative risk reduction.

Application of Number Needed to Treat (NNT) as a Measure of Treatment Effect in Respiratory Medicine

Presentation of clinical data can have a profound effect on treatment decisions, and there is a need for measures that are objective, have clinical relevance, and are easily interpreted. Relative risk is often used to summarize treatment comparisons, but does not account for variations in baseline risk profiles and does not convey information on absolute sizes of treatment effects. Absolute risk reduction gives this information, but the data are dimensionless and abstract, and lack a direct connection with the clinical environment.The number needed to treat, or NNT, has been developed to address this issue. NNT is the reciprocal of the absolute risk reduction associated with an intervention, and may also be calculated as 100 divided by the absolute risk reduction expressed as a percentage. The result is the number of patients who would have to receive treatment for one of them to benefit or to avoid an adverse outcome over a given period of time. Since its introduction, the concept of NNT has been expanded to include number needed to harm (NNH), which illustrates adverse events or other undesirable outcomes associated with treatment, and the epidemiologic tool of number needed to screen.NNT has been used to describe treatment effects from many clinical trials. A recent example illustrates benefit of inhaler therapy combining a long-acting beta(2)-agonist (LABA) and corticosteroid for COPD over treatment with LABA alone. NNT has also been extended to systematic reviews and meta-analyses, where it has been used to rank different treatments where baseline profiles, treatment outcomes and time periods under examination are similar.NNT is therefore a concise and easily understood tool for quantifying treatment efficacy, particularly when applying trial results to the clinic setting.

The role of combination therapy with corticosteroids and long-acting beta2-agonists in the prevention of exacerbations in COPD

Acute exacerbations of COPD can complicate the course of the disease in patients with severe airway obstruction. Reduction of exacerbations is an important clinical outcome in evaluating new therapies in COPD. Combination therapies with long-acting beta-agonists and inhaled corticosteroids have now been approved for use. Three 1-year randomized clinical trials, which studied the effect of combining a long-acting beta2-agonist with an inhaled corticosteroid in COPD, documented that exacerbation frequency was lower with therapy than placebo. Combination therapy had a similar effect to its monocomponents in the trial evaluating salmeterol/fluticasone combination. However, when patients with more severe COPD were studied using a combination of budesonide and formoterol, a clear improvement was seen in the overall exacerbation rates compared with the use of a long-acting beta2-agonist alone.