Is a comparative clinical trial for breast cancer tumor markers to monitor disease recurrence warranted? A value of information analysis

The Value of Decision Analytical Modeling in Surgical Research: An Example of Laparoscopic Versus Open Distal Pancreatectomy

OBJECTIVE

To illustrate how decision modeling may identify relevant uncertainty and can preclude or identify areas of future research in surgery.

SUMMARY BACKGROUND DATA

To optimize use of research resources, a tool is needed that assists in identifying relevant uncertainties and the added value of reducing these uncertainties.

METHODS

The clinical pathway for laparoscopic distal pancreatectomy (LDP) versus open (ODP) for nonmalignant lesions was modeled in a decision tree. Cost-effectiveness based on complications, hospital stay, costs, quality of life, and survival was analyzed. The effect of existing uncertainty on the cost-effectiveness was addressed, as well as the expected value of eliminating uncertainties.

RESULTS

Based on 29 nonrandomized studies (3.701 patients) the model shows that LDP is more cost-effective compared with ODP. Scenarios in which LDP does not outperform ODP for cost-effectiveness seem unrealistic, e.g., a 30-day mortality rate of 1.79 times higher after LDP as compared with ODP, conversion in 62.2%, surgically repair of incisional hernias in 21% after LDP, or an average 2.3 days longer hospital stay after LDP than after ODP. Taking all uncertainty into account, LDP remained more cost-effective. Minimizing these uncertainties did not change the outcome.

CONCLUSIONS

The results show how decision analytical modeling can help to identify relevant uncertainty and guide decisions for future research in surgery. Based on the current available evidence, a randomized clinical trial on complications, hospital stay, costs, quality of life, and survival is highly unlikely to change the conclusion that LDP is more cost-effective than ODP.

What is the value of conducting a trial of r-tPA for the treatment of mild stroke patients?

Background The Phase IIIb, Double-Blind, Multicenter Study to Evaluate the Efficacy and Safety of Alteplase in Patients With Mild Stroke: Rapidly Improving Symptoms and Minor Neurologic Deficits (PRISMS) trial will assess r-tPA in ischemic stroke patients who present with mild deficits (i.e. mild stroke). Aims To assess PRISMS's societal value in clarifying the optimal care for patients with mild ischemic stroke. Methods A value of information (VOI) decision model was developed to compare the outcomes of mild stroke patients treated vs. not treated with r-tPA. Model inputs were derived from a subset of Third International Stroke Trial patients, a recent meta-analysis of r-tPA trials, expert opinion, and other published sources. VOI analyses were also used to assess the expected US societal value of the PRISMS trial and the expected value of reducing uncertainty in key trial estimates. Results The expected net societal value of the PRISMS trial was approximately $210 million ($160 m-$260 m), representing a six-fold return on investment. The value of reducing uncertainty in r-tPA efficacy was approximately $150 million ($100 m-$200 m), while reducing uncertainty in r-tPA safety (increased risk for symptomatic intracranial hemorrhage) did not add additional value in comparison. Conclusions Developing a better understanding of the outcomes of r-tPA treatment in patients with mild ischemic stroke will provide tremendous societal value by clarifying current uncertainty around treatment effectiveness. Enrollment in the PRISMS trial for patients presenting with mild ischemic stroke within 0-3 h of symptom onset should be highly encouraged.

Cost-Effectiveness and Value of Information of Erlotinib, Afatinib, and Cisplatin-Pemetrexed for First-Line Treatment of Advanced EGFR Mutation-Positive Non-Small-Cell Lung Cancer in the United States

OBJECTIVES

To determine the cost-effectiveness of tyrosine kinase inhibitors erlotinib or afatinib, or chemotherapy cisplatin-pemetrexed, for first-line treatment of advanced epithelial growth factor receptor mutation-positive non-small-cell lung cancer in the United States. We also assessed the expected benefit of further research to reduce uncertainty regarding which treatment is optimal.

METHODS

We developed a Markov model to compare the cost-effectiveness of erlotinib, afatinib, and cisplatin-pemetrexed. Model transition and adverse-effect probabilities were from two published phase III trials: EURTAC (Erlotinib versus standard chemotherapy as first-line treatment for European patients with advanced EGFR mutation-positive non-small-cell lung cancer) and LUX-Lung (Afatinib versus cisplatin-based chemotherapy for EGFR mutation-positive lung adenocarcinoma) 3. EURTAC survival estimates were corrected for patients entering the trial with more severe disease, compared with LUX-Lung 3. Health utilities and costs were from national estimates or the published literature. Inputs were modeled as distributions for probabilistic sensitivity analysis and expected value of perfect information (EVPI) analysis to estimate the expected benefit of reducing uncertainty regarding the decision of optimal treatment.

RESULTS

In the base case, both tyrosine kinase inhibitors were more cost-effective than cisplatin-pemetrexed. Erlotinib had an incremental cost-effectiveness ratio of $61,809/quality-adjusted life-year (QALY) compared with afatinib. The acceptability curve showed that erlotinib was the optimal treatment at a willingness-to-pay threshold of $100,000/QALY (10-year population EVPI = $85.9 million). At a willingness-to-pay threshold of $50,000/QALY to $70,000/QALY (EVPI = $211.5 million-$261.8 million), however, there was considerable uncertainty whether erlotinib or afatinib was the optimal treatment.

CONCLUSIONS

Our analysis suggests that erlotinib is the preferred first-line treatment for advanced epithelial growth factor receptor mutation-positive non-small-cell lung cancer. Further research comparing erlotinib and afatinib is potentially justified, although accurate data are needed on the required cost and sample size of the trial.

Sample Size Estimation for Non-Inferiority Trials: Frequentist Approach versus Decision Theory Approach

BACKGROUND

Non-inferiority trials are performed when the main therapeutic effect of the new therapy is expected to be not unacceptably worse than that of the standard therapy, and the new therapy is expected to have advantages over the standard therapy in costs or other (health) consequences. These advantages however are not included in the classic frequentist approach of sample size calculation for non-inferiority trials. In contrast, the decision theory approach of sample size calculation does include these factors. The objective of this study is to compare the conceptual and practical aspects of the frequentist approach and decision theory approach of sample size calculation for non-inferiority trials, thereby demonstrating that the decision theory approach is more appropriate for sample size calculation of non-inferiority trials.

METHODS

The frequentist approach and decision theory approach of sample size calculation for non-inferiority trials are compared and applied to a case of a non-inferiority trial on individually tailored duration of elastic compression stocking therapy compared to two years elastic compression stocking therapy for the prevention of post thrombotic syndrome after deep vein thrombosis.

RESULTS

The two approaches differ substantially in conceptual background, analytical approach, and input requirements. The sample size calculated according to the frequentist approach yielded 788 patients, using a power of 80% and a one-sided significance level of 5%. The decision theory approach indicated that the optimal sample size was 500 patients, with a net value of €92 million.

CONCLUSIONS

This study demonstrates and explains the differences between the classic frequentist approach and the decision theory approach of sample size calculation for non-inferiority trials. We argue that the decision theory approach of sample size estimation is most suitable for sample size calculation of non-inferiority trials.

A PCR blood test outperforms chromogranin A in carcinoid detection and is unaffected by proton pump inhibitors

A critical requirement in neuroendocrine tumor (NET) management is a blood biomarker test that is sensitive, specific and reproducible. We evaluated a PCR-based 51-transcript signature to detect tumors, compared it with chromogranin A (CgA) and examined the confounding effect of proton pump inhibitors (PPIs), which cause falsely elevated CgA levels. The multigene signature was evaluated in two groups. Group 1: 125 prospectively collected NETs: gastroenteropancreatic NETs (n=91, including 42 pancreatic and 40 small intestinal), carcinoids of unknown primary (n=18) and other sites (n=16). Group 2: prospectively collected non-NET patients receiving PPIs (>1 month; dyspepsia, n=19; GERD, n=6; and pancreatitis, n=4) and 50 controls. All samples were analyzed by PCR (marker genes) and ELISA (DAKO-CgA). Sensitivity comparisons included χ(2), non-parametric measurements, and receiver operating characteristic (ROC) curves. Group 1: 123 NETs were PCR-positive (98.4%) compared with 50 (40%) CgA-positive (χ(2)=97.3, P<10(-26)). Significant differences (P<0.001) were noted between pancreas: PCR 95% vs CgA 29.2% (P<10(-9)) and small intestine: 100 vs 58% (P<10(-4)). The multigene test was elevated in all grades (G1-G3), in both local and disseminated disease, and was not normalized by somatostatin analog therapy. It was also elevated in 97% of CgA normal NETs. Group 2: PPI administration increased CgA in 83% and CgA was elevated in 26% of controls. PCR values were not elevated in either group. PCR performance metrics were as follows: sensitivity 98.4%, specificity 100%, positive predictive value 100%, negative predictive value 97.8%, and the ROC-derived area under the curve (AUC) was 0.997. These were significantly better than CgA (all metrics <60%; AUC, 0.54; Z-statistic, 10.44, P<0.0001). A 51-panel multigene blood transcript analysis is significantly more sensitive than plasma CgA for NET detection and is unaffected by acid suppression therapy.

Pilot randomised study of early intervention based on tumour markers in the follow-up of patients with primary breast cancer

BACKGROUND

This pilot study aimed to test the possibility of therapeutic benefit imparted by early intervention based on sequential tumour marker (TM) measurements during follow-up of primary breast cancer (PBC) patients.

METHODS

Patients with oestrogen receptor positive PBC with no clinical and/or radiological evidence of metastases were recruited and followed-up 3-monthly with clinical assessment and TM (CA15.3 and CEA) measurements. The clinical team was blinded to the TM results. Asymptomatic patients who developed raised TMs (based on pre-defined cut-offs) were randomised to either 'treatment change' (either start or change of adjuvant endocrine agent to another agent) or 'no change' (control). Patients who developed symptomatic metastases came off the study. The primary and secondary endpoints were intervals from randomisation to symptomatic metastases and to last follow-up/death respectively.

RESULTS

Eighty-five patients (median age = 54 years (30-72)) were recruited with a median follow-up of 81 months (1-124). Sixteen patients were randomised as described. There was no significant difference (treatment change versus no change) with regards to interval from randomisation to symptomatic metastases - 23 (2-62) and 22 (1-63) months respectively (p = 0.9), as well as interval from randomisation to last follow-up/death - 36 (7-63) and 37 (10-63) months respectively (p = 0.9).

CONCLUSIONS

Despite long follow-up (up to 10+ years), this small study has thus far shown no significant difference in outcome. However, we have confirmed the feasibility of this study design but a larger study will be required to show if there is a benefit to this approach.