Sensitivity to scope in contingent valuation – introducing a flexible community analogy to communicate mortality risk reductions

Validity in contingent valuation (CV) is often tested through the sensitivity of estimated willingness to pay (WTP) to the size or quality of a good or service (‘more is better’ and near proportionality). We investigate the performance of two communication aids (a flexible community analogy and an array of dots) in valuing mortality risk reductions for out-of-hospital cardiac arrest. Our results do not support the prediction of expected utility theory, i.e. that WTP for a mortality risk reduction increases with the amount of risk reduction (weak scope sensitivity), for any of the communication aids. In fact, the array of dots even shows a decreasing WTP when the risk reduction is larger. We find some evidence that level of education influences how communication aids are perceived. Also, a larger municipal population results in lower WTP which may signal problems with strategic bias.Contingent valuation; Willingness to pay; Validity; Sensitivity to scope; Risk communication; Community analogy; Cardiac arrest

The value of a statistical life for out-of-hospital cardiac arrest victims

Background: Economic evaluation of policies regarding out-of-hospital cardiac arrest (OHCA) is important and we estimate the value of a statistical life (VSL) for OHCA victims. Method: Responses to a national Swedish mail survey in 2007, based on the stated-preference technique (contingent valuation) to directly elicit individuals hypothetical willingness to pay for a reduced risk of dying from OHCA. Results: VSL values are found to be higher than for comparable VSL estimates from the transport sector. A lower-bound estimate of VSL for OHCA would be around SEK 20-30 million. Conclusions: The results in this paper indicates that it is not an overestimation to use the „baseline VSL value from the transport sector (SEK 22 million) in cost-benefit analysis of OHCA policy decisions. We do not support a senior death discount for this cause of death.Contingent valuation; Value of a statistical life; Cardiac arrest

Certainty calibration in contingent valuation - exploring the within-difference between dichotomous choice and open-ended answers as a certainty measure

Hypothetical bias is a serious problem of stated preference techniques. The certainty approach calibrates answers by assessing different weights to remedy respondents’ valuation. However, very little research has been done to find a link between economic theory and empirical treatment of uncertainty through certainty calibration. We use a combination of dichotomous choice (DC) followed by an open-ended (OE) question to examine the relation between the degree of confidence and the distance between the DC bid and the OE answer. The results show that the OE bid difference is significantly correlated to the certainty level in one of our two contingent valuation (CV) surveys, with the probability of stating the highest confidence value increasing between 5-19 percent per SEK 1000 (~$170/€106) that the answer to the OE question and the bid differ. The second CV survey shows a significant relation for the no-responders.Contingent valuation; Hypothetical bias; Calibration; Certainty approach; Value of a statistical life; Traffic safety; Cardiac arrest

Favourable cost-benefit in an early defibrillation program using dual dispatch of ambulance and fire services in out-of-hospital cardiac arrest

Aims: Out-of-hospital cardiac arrest (OHCA) is fatal without treatment and time to defibrillation is an extremely important factor in relation to survival. We performed a cost-benefit analysis of dual dispatch defibrillation by ambulance and fire services in the County of Stockholm, Sweden. Methods and Results: A cost-benefit analysis was performed to evaluate the effects of dual dispatch defibrillation. The increased survival rates were estimated from a real world implemented intervention and the monetary value of a life (€ 2.2 million) was applied to this benefit by using results from a recent stated-preference study. The estimated costs include defibrillators (including expendables/maintenance), training, hospitalisation/health care, call-outs for the fire services, overhead resources and costs for the dispatch centre. The estimated number of additional saved lives was 16 per year, yielding a benefit-cost ratio of 36. The cost per quality-adjusted life years (QALY) was estimated to be € 13 000 and the cost per saved life was € 60 000. Conclusions: The intervention of dual dispatch defibrillation by ambulance and fire services in the County of Stockholm had positive economic effects. For the cost-benefit analysis the return on investment was high and the cost-effectiveness showed levels below the threshold value for economic efficiency used in Sweden. The cost-utility analysis categorises the cost per QALY as medium.Cost-benefit analysis; cost-utility analysis; cost-effectiveness analysis; cardiac arrest; defibrillation; ambulance; fire services

Plasma antibodies to oral bacteria and risk of pancreatic cancer in a large European prospective cohort study

Objective: Examine the relationship between antibodies to 25 oral bacteria and pancreatic cancer risk in a prospective cohort study. Design: We measured antibodies to oral bacteria in prediagnosis blood samples from 405 pancreatic cancer cases and 416 matched controls, nested within the European Prospective Investigation into Cancer and Nutrition study. Analyses were conducted using conditional logistic regression and additionally adjusted for smoking status and body mass index. Results: Individuals with high levels of antibodies against Porphyromonas gingivalis ATTC 53978, a pathogenic periodontal bacteria, had a twofold higher risk of pancreatic cancer than individuals with lower levels of these antibodies (OR 2.14; 95% CI 1.05 to 4.36; >200ng/ml vs 200ng/ml). To explore the association with commensal (non-pathogenic) oral bacteria, we performed a cluster analysis and identified two groups of individuals, based on their antibody profiles. A cluster with overall higher levels of antibodies had a 45% lower risk of pancreatic cancer than a cluster with overall lower levels of antibodies (OR 0.55; 95% CI 0.36 to 0.83). Conclusion: Periodontal disease might increase the risk for pancreatic cancer. Moreover, increased levels of antibodies against specific commensal oral bacteria, which can inhibit growth of pathogenic bacteria, might reduce the risk of pancreatic cancer. Studies are needed to determine whether oral bacteria have direct effects on pancreatic cancer pathogenesis or serve as markers of the immune response

The prognostic impact of the tumour stroma fraction: A machine learning-based analysis in 16 human solid tumour types

Background: The development of a reactive tumour stroma is a hallmark of tumour progression and pronounced tumour stroma is generally considered to be associated with clinical aggressiveness. The variability between tumour types regarding stroma fraction, and its prognosis associations, have not been systematically analysed.Methods: Using an objective machine-learning method we quantified the tumour stroma in 16 solid cancer types from 2732 patients, representing retrospective tissue collections of surgically resected primary tumours. Image analysis performed tissue segmentation into stromal and epithelial compartment based on pan-cytokeratin staining and autofluorescence patterns.Findings: The stroma fraction was highly variable within and across the tumour types, with kidney cancer showing the lowest and pancreato-biliary type periampullary cancer showing the highest stroma proportion (median 19% and 73% respectively). Adjusted Cox regression models revealed both positive (pancreato-biliary type periampullary cancer and oestrogen negative breast cancer, HR(95%CI)=0.56(0.34-0.92) and HR (95%CI)=0.41(0.17-0.98) respectively) and negative (intestinal type periampullary cancer, HR(95%CI)=3.59 (1.49-8.62)) associations of the tumour stroma fraction with survival.Interpretation: Our study provides an objective quantification of the tumour stroma fraction across major types of solid cancer. Findings strongly argue against the commonly promoted view of a general associations between high stroma abundance and poor prognosis. The results also suggest that full exploitation of the prognostic potential of tumour stroma requires analyses that go beyond determination of stroma abundance.</p

Mortality-risk valuation, age and cause of death: out-of-hospital cardiac arrest

Economic evaluation of policies regarding out-of-hospital cardiac arrest (OHCA) is important. The value of a statistical life (VSL) for OHCA victims is the most important component in a cost-benefit analysis of interventions that have the possibility to reduce mortality from this cause. This value is not known. We use responses to a national Swedish mail survey, based on the stated-preference technique to directly elicit individuals’ hypothetical willingness to pay for a reduced risk of dying from OHCA. A lower-bound estimate of VSL for OHCA would be in range of SEK 30 to 50 million. The value is found to be higher than for comparable VSL estimates from the transport sector, even though individuals who suffer OHCAs are generally older and less healthy than people who die in road traffic accidents. The results indicate that it is not an overestimation to use the ‘baseline’ VSL value from the transport sector (SEK 24 million) in cost-benefit analysis of OHCA policy decisions and that the cause of death is important when examining willingness to pay for death risk reductions. We do not support a general declining VSL due to the age of the victims, i.e. a ‘senior death discount’, for this cause of death.Published: Online January 2017. In print December 2017

Economic evaluation, value of life, stated preference methodology and determinants of risks

The first paper examines the value of a statistical life (VSL) for out-of-hospital cardiac arrest (OHCA) victims. We found VSL values to be higher for OHCA victims than for people who die in road traffic accidents and a lower-bound estimate of VSL for OHCA would be in the range of 20 to 30 million Swedish crowns (SEK). The second paper concerns hypothetical bias in contingent valuation (CV) studies. We investigate the link between the determinants and empirical treatment of uncertainty through certainty calibration and find that the higher the confidence of the respondents the more we can trust that stated WTP is correlated to actual WTP. The third paper investigates the performance of two communication aids (a flexible community analogy and an array of dots) in valuing mortality risk reductions for OHCA. The results do not support the prediction of expected utility theory, i.e. that WTP for a mortality risk reduction increases with the amount of risk reduction (weak scope sensitivity), for any of the communication aids. The fourth paper presents a cost-benefit analysis to evaluate the effects of dual dispatch defibrillation by ambulance and fire services in the County of Stockholm. The intervention had positive economic effects, yielding a benefit-cost ratio of 36, a cost per quality-adjusted life-year (QALY) of € 13 000 and the cost per saved life was € 60 000. The fifth paper explores how different response times from OHCA to defibrillation affect patients’ survival rates by using geographic information systems (GIS). The model predicted a baseline survival rate of 3.9% and reducing the ambulance response time by 1 minute increased survival to 4.6%. The sixth paper analyzes demographic determinants of incident experience and risk perception, and the relationship between the two, for eight different risk domains. Males and highly educated respondents perceive their risks lower than what is expected compared to actual incident experience