Estimating the 95% confidence interval for survival gain between an experimental anti-cancer treatment and a control

An Overview of the Fundamentals of Data Management, Analysis, and Interpretation in Quantitative Research

OBJECTIVES

To provide an overview of three consecutive stages involved in the processing of quantitative research data (ie, data management, analysis, and interpretation) with the aid of practical examples to foster enhanced understanding.

DATA SOURCES

Published scientific articles, research textbooks, and expert advice were used.

CONCLUSION

Typically, a considerable amount of numerical research data is collected that require analysis. On entry into a data set, data must be carefully checked for errors and missing values, and then variables must be defined and coded as part of data management. Quantitative data analysis involves the use of statistics. Descriptive statistics help summarize the variables in a data set to show what is typical for a sample. Measures of central tendency (ie, mean, median, mode), measures of spread (standard deviation), and parameter estimation measures (confidence intervals) may be calculated. Inferential statistics aid in testing hypotheses about whether or not a hypothesized effect, relationship, or difference is likely true. Inferential statistical tests produce a value for probability, the P value. The P value informs about whether an effect, relationship, or difference might exist in reality. Crucially, it must be accompanied by a measure of magnitude (effect size) to help interpret how small or large this effect, relationship, or difference is. Effect sizes provide key information for clinical decision-making in health care.

IMPLICATIONS FOR NURSING PRACTICE

Developing capacity in the management, analysis, and interpretation of quantitative research data can have a multifaceted impact in enhancing nurses' confidence in understanding, evaluating, and applying quantitative evidence in cancer nursing practice.

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

INTRODUCTION

On the basis of two randomized trials, evolocumab and alirocumab have been approved in patients with cardiovascular disease. The evidence on these two agents has been studied through different methods of analysis that span from narrative approaches to network meta-analysis. In the present study, we assessed the performance of a narrative approach combined with the application of the restricted mean survival time (RMST).

METHODS

We studied the two pivotal placebo-controlled trials focused on evolocumab and alirocumab. Our original framework of comparative assessment employed the RMST. Our objective was to show that in the context of a narrative review, the RMST can be an efficient although simple tool to make indirect comparisons. The endpoint was event-free survival, expressed in months.

RESULTS

For each cohort of patients (13,784 patients administered evolocumab, 9462 patients administered alirocumab, 23,242 controls), we determined the RMST values with 95% confidence intervals (CI) [evolocumab: 33.60 months, 95% CI 33.46-33.74; alirocumab: 34.07 months, 95% CI 33.92-34.22]. These results, along with those of the control groups, were analyzed and interpreted narratively. Univariate statistics were conducted, but no network meta-analysis was performed.

CONCLUSION

The experience presented herein indicates that a framework of evidence assessment focused on the RMST is a worthwhile option. Our study is in line with the growing literature that has recently emphasized the methodological advantages of the RMST.

Restricted mean survival time as outcome measure in advanced urothelial bladder cancer: analysis of 4 clinical studies

Background: The purpose of this study was to assess the effectiveness of immune checkpoint inhibitors (ICIs) in advanced urothelial carcinoma. Materials & methods: We selected seven cohorts of patients published in four clinical trials. The restricted mean survival time (RMST) was used to analyze survival curves, perform the comparisons and rank the treatments based on their effectiveness. The performance of RMST was compared with that of a network meta-analysis. Results: Three ICIs, vinflunine and best standard care, given as second line, were examined. ICIs significantly improved overall survival compared with best standard care. However, the survival gain was quite limited (up to 2.27 months). Post hoc pairwise comparisons were calculated. Conclusion: Our results summarized the efficacy of these treatments and confirmed the good methodological performance of RMST.

Outcomes at 5 years in patients with severe aortic stenosis: reviewing current information using the restricted mean survival time

The information about outcomes at 5 years in patients receiving transcatheter aortic valve replacement (TAVR) has grown. We interpreted the information on this topic using the restricted mean survival time (RMST). The purpose of our study was to summarise the current evidence using an original outcome measure with potential methodological advantages. Four cohorts of patients, previously published in the literature, met our criterion of 5 years of follow-up after the implant; another cohort was identified from a group of controls subjected to surgical replacement of the valve. The estimated values of RMST at 5 years for the 5 patient cohorts were the following (N = number of patients, all time values in years): a) real-world high surgical risk cohort: N = 114, RMST = 3.80; b) real-world cohort treated with Corevalve: N = 309, RMST = 3.79; c) a real-world cohort treated with Sapien: N = 180, RMST = 3.61; d) TAVR arm of a randomized trial in intermediate risk patients: N = 1,011; RMST = 3.73; e) surgical replacement arm of the same trial: N = 1,021, RMST = 3.72. The main result of our analysis based on the RMST is represented by the extreme homogeneity of the outcomes (RMSTs ranging from 3.61 to 3.80 years per patient) that remained virtually constant irrespective of the baseline risk of the patients (intermediate or high risk) and regardless of whether the intervention was transcatheter or by surgical replacement. Last but not least, our analysis showed the good methodological performance of the RMST in this disease condition.