The Restricted Mean Survival Time as a Tool for Ranking Comparative Outcomes in a Narrative Review that Evaluates a Network of Randomized Trials: An Example Based on PCSK9 Inhibitors

Time Gained to Cardiovascular Disease by Intensive Lipid-Lowering Therapy: Results of Individual Placebo-Controlled Trials and Pooled Effects

INTRODUCTION

Despite the effect on blood lipid levels, the clinical benefits of intensive versus standard pharmacological lipid-lowering therapy remain unclear. Previous reviews have presented relative effects on the risk of clinical outcomes, but not the absolute risk reductions (ARRs) and the time gained to a clinical outcome, also called outcome postponement (OP). The aim of this study was to estimate the effect of intensive versus standard lipid-lowering therapy in terms of ARR and OP of major adverse cardiovascular events (MACE), myocardial infarction (MI), stroke, and all-cause mortality.

METHODS

We searched PubMed, Embase, and prior reviews to identify trials comparing intensive versus standard lipid-lowering therapy for the risk of cardiovascular disease. We extracted the number of patients with MACE, MI, stroke, and all-cause mortality. Risk of bias was assessed according to the five domains of the Cochrane Risk of Bias Tool 2.0. We calculated ARRs and OPs to assess the clinical benefits of intensive versus standard therapy for each outcome. We conducted meta-analyses standardizing the results to 2 and 5 years of follow-up.

RESULTS

We identified 11 double-blind, randomized, controlled trials (n = 101,357). The follow-up period ranged from 1.5 to 7.0 years, with an average follow-up duration of 3.7 years. Risk of bias was generally high. During an estimated 2 years of intensive versus standard lipid-lowering therapy, 1.1% (95% confidence interval [CI] 0.7-1.5) fewer patients had MACE and the OP of MACE was 4.1 days (95% CI 2.6-5.6). The effects were 0.7% (95% CI 0.4-0.8) and 2.5 days (95% CI 1.6-3.3) for MI, 0.2% (95% CI 0.1-0.3) and 0.9 days (95% CI 0.5-1.2) for stroke, and 0.2% (95% CI - 0.1 to 0.4) and 0.6 days (95% CI - 0.4 to 1.5) for all-cause death. During on average 5 years of intensive versus standard lipid-lowering therapy, 2.4% (95% CI 1.5-3.3) fewer patients had MACE and the time gained to MACE was 23.5 days (95% CI 14.9-32.0). The effects were 1.5% (95% CI 1.0-2.1) and 14.6 days (95% CI 9.3-20.0) for MI, 0.6% (95% CI 0.4-0.8) and 5.3 days (95% CI 3.3-7.4) for stroke, and 0.4% (95% CI -0.2 to 0.1) and 3.6 days (95% CI - 2.1 to 9.2) for all-cause death.

CONCLUSION

Intensive lipid-lowering therapy during 2 or 5 years did not lead to fewer deaths or lifetime gained, and the effects on MI and stroke were negligible. The largest effect was that MACE did not occur in two of 100 patients and was postponed 3-4 weeks after 5 years of intensive treatment. Given the small effect, patients should receive this information as part of shared decision making.

First-line chemoimmunotherapy versus chemotherapy in PD-L1-negative patients with non-small-cell lung cancer

Background: In PD-L1-negative patients with advanced non-small-cell lung cancer (NSCLC), conclusive evidence in support of specific treatments remains lacking. Objectives: The efficacy of first-line chemoimmunotherapy versus chemotherapy alone was compared. Methods: Eligible randomized studies that included patients with advanced NSCLC irrespective of PD-L1 status who were treated with chemoimmunotherapy as the first line were identified. Kaplan-Meier curves were extracted and analyzed using restricted mean survival time (RMST). Patient-level data were reconstructed from progression-free survival (PFS) graphs. A Bayesian network meta-analysis (NETMA) was carried out. Results: In five trials selected, chemoimmunotherapy regimens, compared with chemotherapy alone, resulted in an improvement in PFS without statistical significance. In the NETMA, chemoimmunotherapy was found to slightly improve PFS. Conclusion: This analysis showed that the incremental benefit of chemoimmunotherapy versus chemotherapy is limited.

Adjuvant Nivolumab in Esophageal or Gastroesophageal Junction Cancer: the Improvement in Progression-Free Survival Is Small

Esophageal cancer is the seventh most common cancer globally, accounting more than a half million deaths per year. Despite several therapeutic options in neoadjuvant setting, including chemoradiotherapy and surgery, no adjuvant treatment has been established for patients at high risk of recurrence. Even so, findings from the recently published CheckMate 577 trial seem to suggest an important clinical impact, in terms of disease-free progression, for the use of adjuvant nivolumab, a PDL-1 inhibitor, in resected esophageal cancer or gastroesophageal junction cancer. The authors reported a benefit for the treatment arm of 22.4 months compared with 11.0 in the placebo group. Although median is commonly used as an endpoint in survival studies, it can be influenced by the timing of a few events in the descending portion of the Kaplan-Meier curve. Restricted mean survival time (RMST) considers the entire time-course of the curve and does not assume that event risks are constant over the follow-up. This may be helpful to a more realistic interpretation of survival outcomes. In this letter, we re-analyzed the study curves of the CheckMate 577 trial by application of RMST. While confirming the disease-free progression benefits for nivolumab compared with placebo (28.54 months for the treatment arms versus 22.70 for the controls), our analysis allows us to interpret the survival benefit in a more conservative manner.

The restricted mean survival time as a replacement for the hazard ratio and the number needed to treat in long-term studies

Aims

We applied the restricted mean survival time (RMST) to analyse the survival data reported in the PARADIGM‐HT trial in which sacubitril + valsartan was studied in comparison with enalapril in patients with heart failure. The estimates of this parameter were compared with the published values of hazard ratio (HR).

Methods

Two endpoints were evaluated: a composite of death or hospitalization and cardiovascular death. Our analyses were performed by considering the original follow‐up of 41.4 months and on the basis of a lifetime perspective. All statistical calculations were carried out using specific packages developed under the R‐platform.

Results

According to our RMST analysis, the results for the composite endpoint in the comparison of sacubitril + valsartan vs. enalapril showed an improvement from 32.9 to 34.2 months (gain of 1.25 months). This result is based on a time horizon of 41.4 months. The results for the cardiovascular mortality endpoint showed a RMST of 37.2 months for sacubitril + valsartan vs. 36.2 for enalapril (gain of 0.96 months). In the two lifetime analyses, the improvements were much more relevant and yielded a gain of 25.8 months for the composite endpoint and 27.6 months for survival free from cardiovascular death.

Conclusions

Using the data of the PARADIGM‐HT trial, our analysis confirmed that the RMST has documented advantages over the HR, particularly when the clinical study is characterized by a long follow‐up. The number needed to treat (NNT) has a more specific methodological role and cannot be replaced by the RMST.