CONSUMERS' WILLINGNESS TO PAY FOR THE COLOR OF SALMON:A CHOICE EXPERIMENT WITH REAL ECONOMIC INCENTIVES

We designed an experimental market with posted prices to investigate consumers' willingness to pay for the color of salmon. Salmon fillets varying in color and price were displayed in 20 choice scenarios. In each scenario, the participants chose which of two salmon fillets they wanted to buy. To induce real economic incentives, each participant drew one unique binding scenario; the participants then had to buy the salmon fillet they had chosen in their binding scenario.Consumer/Household Economics,

Utvikling av et bærekraftig modulbasert byggesystem : ombruk av restmaterialer og vurdering av klimagassutslipp

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CONSUMERS ’ WILLINGNESS TO PAY FOR THE COLOR OF SALMON: ACHOICE EXPERIMENT WITH REAL ECONOMIC INCENTIVES

In most retail markets, sellers post the price and consumers choose which products to buy. We designed an experimental market with posted prices to investigate consumers ’ willingness to pay for the color of salmon. Salmon fillets varying in color and price were displayed in twenty choice scenarios. In each scenario, the participants chose which of two salmon fillets they wanted to buy. To induce real economic incentives, each participant drew one binding scenario; the participants then had to buy the salmon fillet they had chosen in their binding scenario. The choice data were analyzed with a mixed logit model. Key words: choice experiment, color, mixed logit, salmon, willingness to pay. During the past decade, economists have used experimental markets to investigate consumer preferences and willingness to pay (WTP) for food quality attributes. The most popular method has been the second-price sealedbid Vickrey auction (Vickrey 1961) where participants submit sealed bids for the product and the price is determined by the secondhighest bid, see, for example, Shogren et al. (1994); Alfnes and Rickertsen (2003). The Vickrey auction is an incentive-compatible method for eliciting WTP. However, it is an unfamiliar market mechanism for most consumers. Consumers are more familiar with markets where the seller posts prices and they, as consumers, have to choose which products to buy. Lusk and Schroeder (2004a) designed an experimental market with posted prices to investigate consumers ’ WTP for food quality Frode Alfnes is a postdoctoral fellow and Atle G. Guttormsen is

AJAE APPENDIX: CONSUMERS’ WILLINGNESS TO PAY FOR THE COLOR OF SALMON: A CHOICE EXPERIMENT WITH REAL ECONOMIC INCENTIVES

The material contained herein is supplementary to the article named in the title and published in the American Journal of Agricultural Economics, Volume 88, Number 4, November 2006.Consumer/Household Economics, Demand and Price Analysis,

Anterior surgical treatment for cervical degenerative radiculopathy: a prediction model for non-success

Purpose By using data from the Norwegian Registry for Spine Surgery, we wanted to develop and validate prediction models for non-success in patients operated with anterior surgical techniques for cervical degenerative radiculopathy (CDR). Methods This is a multicentre longitudinal study of 2022 patients undergoing CDR surgery and followed for 12 months to fnd prognostic models for non-success in neck disability and arm pain using multivariable logistic regression analysis. Model performance was evaluated by area under the receiver operating characteristic curve (AUC) and a calibration test. Internal validation by bootstrapping re-sampling with 1000 repetitions was applied to correct for over-optimism. The clinical usefulness of the neck disability model was explored by developing a risk matrix for individual case examples. Results Thirty-eight percent of patients experienced non-success in neck disability and 35% in arm pain. Loss to follow-up was 35% for both groups. Predictors for non-success in neck disability were high physical demands in work, low level of education, pending litigation, previous neck surgery, long duration of arm pain, medium-to-high baseline disability score and presence of anxiety/depression. AUC was 0.78 (95% CI, 0.75, 0.82). For the arm pain model, all predictors for non-success in neck disability, except for anxiety/depression, were found to be signifcant in addition to foreign mother tongue, smoking and medium-to-high baseline arm pain. AUC was 0.68 (95% CI, 0.64, 0.72). Conclusion The neck disability model showed high discriminative performance, whereas the arm pain model was shown to be acceptable. Based upon the models, individualized risk estimates can be made and applied in shared decision-making with patients referred for surgical assessment

Non-respondents do not bias outcome assessment after cervical spine surgery: a multicenter observational study from the Norwegian registry for spine surgery (NORspine)

Background - The Norwegian registry for spine surgery (NORspine) is a national clinical quality registry which has recorded more than 10,000 operations for degenerative conditions of the cervical spine since 2012. Registries are large observational cohorts, at risk for attrition bias. We therefore aimed to examine whether clinical outcomes differed between respondents and non-respondents to standardized questionnaire-based 12-month follow-up. Methods - All eight public and private providers of cervical spine surgery in Norway report to NORspine. We included 334 consecutive patients who were registered with surgical treatment of degenerative conditions in the cervical spine in 2018 and did a retrospective analysis of prospectively collected register data and data on non-respondents’ outcomes collected by telephone interviews. The primary outcome measure was patient-reported change in arm pain assessed with the numeric rating scale (NRS). Secondary outcome measures were change in neck pain assessed with the NRS, change in health-related quality of life assessed with EuroQol 5 Dimensions (EQ-5D), and patients’ perceived benefit of the operation assessed by the Global Perceived Effect (GPE) scale. Results - At baseline, there were few and small differences between the 238 (71.3%) respondents and the 96 (28.7%) non-respondents. We reached 76 (79.2%) non-respondents by telephone, and 63 (65.6%) consented to an interview. There was no statistically significant difference between groups in change in NRS score for arm pain (3.26 (95% CI 2.84 to 3.69) points for respondents and 2.77 (1.92 to 3.63) points for telephone interviewees) or any of the secondary outcome measures. Conclusions - The results indicate that patients lost to follow-up were missing at random. Analyses of outcomes based on data from respondents can be considered representative for the complete register cohort, if patient characteristics associated with attrition are controlled for

Volume and densities of chronic subdural haematoma obtained from CT imaging as predictors of postoperative recurrence: a prospective study of 107 operated patients

BACKGROUND: Chronic subdural haematoma (CSDH) is a common entity in neurosurgery with a considerable postoperative recurrence rate. Computerised tomography (CT) scanning remains the most important diagnostic test for this disorder. The aim of this study was to characterise the relationship between the recurrence of CSDH after treatment with burr-hole irrigation and closed-system drainage technique and CT scan features of these lesions to assess whether CT findings can be used to predict recurrence. METHODS: We investigated preoperative and postoperative CT scan features and recurrence rate of 107 consecutive adult surgical cases of CSDH and assessed any relationship with univariate and multivariate regression analyses. RESULTS: Seventeen patients (15.9 %) experienced recurrence of CSDH. The preoperative haematoma volume, the isodense, hyperdense, laminar and separated CT densities and the residual total haematoma cavity volume on the 1st postoperative day after removal of the drainage were identified as radiological predictors of recurrence. If the preoperative haematoma volume was under 115 ml and the residual total haematoma cavity volume postoperatively was under 80 ml, the probability of no recurrence was very high (94.4 % and 97.4 % respectively). CONCLUSIONS: These findings from CT imaging may help to identify patients at risk for postoperative recurrence

Impact of the number of previous lumbar operations on patient-reported outcomes after surgery for lumbar spinal stenosis or lumbar disc herniation

Aims - Repeated lumbar spine surgery has been associated with inferior clinical outcomes. This study aimed to examine and quantify the impact of this association in a national clinical register cohort. Methods - This is a population-based study from the Norwegian Registry for Spine surgery (NORspine). We included 26,723 consecutive cases operated for lumbar spinal stenosis or lumbar disc herniation from January 2007 to December 2018. The primary outcome was the Oswestry Disability Index (ODI), presented as the proportions reaching a patient-acceptable symptom state (PASS; defined as an ODI raw score ≤ 22) and ODI raw and change scores at 12-month follow-up. Secondary outcomes were the Global Perceived Effect scale, the numerical rating scale for pain, the EuroQoL five-dimensions health questionnaire, occurrence of perioperative complications and wound infections, and working capability. Binary logistic regression analysis was conducted to examine how the number of previous operations influenced the odds of not reaching a PASS. Results - The proportion reaching a PASS decreased from 66.0% (95% confidence interval (CI) 65.4 to 66.7) in cases with no previous operation to 22.0% (95% CI 15.2 to 30.3) in cases with four or more previous operations (p Conclusion - We found a dose-response relationship between increasing number of previous operations and inferior outcomes among patients operated for degenerative conditions in the lumbar spine. This information should be considered in the shared decision-making process prior to elective spine surgery

The Norwegian registry for spine surgery (NORspine): cohort profile

Purpose - To review and describe the development, methods and cohort of the lumbosacral part of the Norwegian registry for spine surgery (NORspine). Methods - NORspine was established in 2007. It is government funded, covers all providers and captures consecutive cases undergoing operations for degenerative disorders. Patients’ participation is voluntary and requires informed consent. A set of baseline-, process- and outcome-variables (3 and 12 months) recommended by the International Consortium for Health Outcome Measurement is reported by surgeons and patients. The main outcome is the Oswestry disability index (ODI) at 12 months. Results - We show satisfactory data quality assessed by completeness, timeliness, accuracy, relevance and comparability. The coverage rate has been 100% since 2016 and the capture rate has increased to 74% in 2021. The cohort consists of 60,647 (47.6% women) cases with mean age 55.7 years, registered during the years 2007 through 2021. The proportions > 70 years and with an American Society of Anaesthesiologists’ Physical Classification System (ASA) score > II has increased gradually to 26.1% and 19.3%, respectively. Mean ODI at baseline was 43.0 (standard deviation 17.3). Most cases were operated with decompression for disc herniation (n = 26,557, 43.8%) or spinal stenosis (n = 26,545, 43.8%), and 7417 (12.2%) with additional or primary fusion. The response rate at 12 months follow-up was 71.6%. Conclusion - NORspine is a well-designed population-based comprehensive national clinical quality registry. The register’s methods ensure appropriate data for quality surveillance and improvement, and research

Internt Kvalitetsregister for Kirurgisk behandling av Intraspinale Svulster

Det er estimert ca. 75 operasjoner på ny diagnostiserte intraspinale svulster per år i Norge. Med intraspinale svulster menes alle svulster i spinalkanalen, fra foramen magnum til coccyx. De primære svulstene utgår fra ryggmarg, ryggmarghinnene, spinalnerver og filum terminale. Noen pasienter som blir behandlet operativt får en bra behandling og kan returnere til et normalt liv, men andre får en livssituasjon preget av kronisk smerte og funksjonsforstyrrelser. Hvilke pasienter som har mest nytte av operativ behandling og hvilken type operasjon som bør tilbys er i mange situasjoner omdiskutert. Kvalitetssikring og oppfølgingsrutiner kan forbedres. Målet var å gi en oversikt over fagfeltet samt lage et lokalt kvalitetsregister som et verktøy for å få en mer definert praksis når det gjelder indikasjonsstilling, operasjonsteknikk, kvalitetssikring og oppfølgingsrutiner. Registeret er basert på spørreskjemaer som pasient og behandler svarer på i forbindelse med operasjonen og påfølgende polikliniske kontroller. Bakgrunnsvariabler som demografiske data, klinisk status, radiologiske utredningsfunn, operasjonstekniske forhold og tumorhistologi blir registrert. Kliniske endepunkter er valgt som kvalitetsmål; Pasientens tilfredshet med behandlingen, yrkesstatus, smerteregistrering, komplikasjonsregistrering, funksjonsregistrering (i form av European Myelopathy Score, Modified McCormic Score , Ranawat Score, ASIA Impairment Scale) og livskvalitetsregistrering (i form av EQ-5D). Registerverktøyet som er benyttet er MedInsight. Dette er konstruert for å lage spesialiserte medisinske registre med innebygd rapportfunksjonalitet for kontinuerlig tilgang til egne data