Probit Models with Binary Endogenous Regressors

Sample selection and endogeneity are frequent causes of biases in non-experimental empirical studies. In binary models a standard solution involves complex multivariate models. A simple approximation has been shown to work well in bivariate models. This paper extends the approximation to a trivariate model. Simulations show that the approximation outperforms full maximum likelihood while a least squares approximation may be severely biased. The methods are used to estimate the influence of trust in the parliament and politicians on voting- propensity. No previous studies have allowed for endogeneity of trust on voting and it is shown to severely affect the results.endogeneity; multivariate probit; approximation; Monte Carlo simulation

Digital health in pain assessment, diagnosis, and management: Overview and perspectives

Managing pain is essential for social, psychological, physical, and economic reasons. It is also a human right with a growing incidence of untreated and under-treated pain globally. Barriers to diagnosing, assessing, treating, and managing pain are complicated, subjective, and driven by patient, healthcare provider, payer, policy, and regulatory challenges. In addition, conventional treatment methods pose their own challenges including the subjectivity of assessment, lack of therapeutic innovation over the last decade, opioid use disorder and financial access to treatment. Digital health innovations hold much promise in providing complementary solutions to traditional medical interventions and may reduce cost and speed up recovery or adaptation. There is a growing evidence base for the use of digital health in pain assessment, diagnosis, and management. The challenge is not only to develop new technologies and solutions, but to do this within a framework that supports health equity, scalability, socio-cultural consideration, and evidence-based science. The extensive limits to physical personal interaction during the Covid-19 pandemic 2020/21 has proven the possible role of digital health in the field of pain medicine. This paper provides an overview of the use of digital health in pain management and argues for the use of a systemic framework in evaluating the efficacy of digital health solutions

Pain catastrophizing in the elderly:An experimental pain study

OBJECTIVES: Pain catastrophizing in the aging population has not been studied in great detail. Existing investigations have reported conflicting results on the effects of age on pain catastrophizing in relation to pain responses. This study investigated the relationship between pain catastrophizing, and its individual components (rumination, magnification, and helplessness), and the responses to standardized experimental pain stimuli in old and young, healthy adults.METHODS: Sixty-six volunteers (32 old: 65-87, 18 females; 34 young: 20-35, 17 females) participated in the study. Pain catastrophizing including the components of rumination, magnification, and helplessness was assessed with the pain catastrophizing scale (PCS). Experimental pain was induced by applying predefined pressure stimulations to the trapezius muscle. Pain intensity and unpleasantness were assessed using numerical rating scales. Pain catastrophizing levels and pain responses were statistically compared between the two age groups.RESULTS: Elderly individuals reported significantly (p = 0.028) lower scores of pain catastrophizing (Med = 5; interquartile range [IQR] = 14) than younger individuals; this difference was driven by the significantly lower components of rumination (Med = 2; IQR = 4; p = 0.017) and helplessness (Med = 2; IQR = 7; p = 0.049). A larger proportion of young (57.8%) rated pain catastrophizing at high levels, with scores above the 75th percentile (Med = 20). Additionally, elderly reported the lowest pain intensity (Med = 5; p = 0.034) and pain unpleasantness (Med = 4.5; p = 0.011) responses to the experimental pressure stimuli. In the elderly group, pain unpleasantness was positively and significantly associated with pain catastrophizing (r s = 0.416, p = 0.021), rumination (r s = 0.42, p = 0.019), and helplessness (r s = 0.434, p = 0.015), respectively. No associations were found in the young group.CONCLUSIONS: Elderly reported lower PCSs than young adults. Rumination and helplessness were reduced in the elderly group. The elderly population showed positive correlations between catastrophizing levels and pain unpleasantness to standardized pressure pain stimuli. Results supported the view that elderly possess resilience over specific domains of pain catastrophizing that could counteract pain perception due to physiological decline.</p

Acid-induced experimental muscle pain and hyperalgesia with single and repeated infusion in human forearm

Abstract Background and purpose Acid has long been thought to play an important role in the pain process. Animal study showed that repeated acid stimulation induced central sensitization. The purpose of the study is to investigate muscle pain and hyperalgesia evoked byintramuscular infusion of saline at different pH levels, and to compare the effect of a single versus repeated acid infusions. Methods Twenty healthy subjects received infusions of buffered saline (pH 5.0, 6.0, and 7.4) into the brachioradialis muscle in a randomized order. Twelve of the subjects received repeated infusions. The subjects rated the pain intensity on visual analogue scale (VAS). Thermal pain sensitivity, and pressure pain threshold (PPT) were assessed in both arm before, during, immediately after, one hour after, and one day after the infusion. A McGill Pain Questionnaire and pain mapping were completed after each infusion. Results The pH 5 solution caused significantly higher pain and larger areas than pH 6.0 or 7.4. The local PPTs were significantly decreased (hyperalgesia) during and immediately after infusion of all three solutions. No significant differences were detected between the first and second infusion. Conclusions The intensity of acid-induced muscle pain is pH-dependent. All three solutions induced pressure hyperalgesia at the infusion site. Repeated infusions did not induce increased pain or prolonged hyperalgesia as compared with a single injection. Human intramuscular acidic saline infusion could not produce chronic pain model. Implications The acid-induced pain model may reflect the early stage responses to tissue injury of clinical conditions. Repeated intramuscular acidic saline injection model of prolonged hyperalgesia in rodents could not be translated into a human for modelling chronic musculoskeletal pain. </jats:sec