Preoperative pain, state anxiety, pain quality descriptors, opioid consumption, and early postoperative pain may be important predictors of chronic postsurgical pain, which require further investigation.

Women had a higher prevalence - but not incidence - of chronic pain compared with men, indicative of longer duration of illness in women. Risk factors also differed according to sex, supporting current literature reporting potentially different mechanisms for men and women. A better understanding of risk factors is necessary to develop population-based preventive interventions. The former can only be achieved with population-based, longitudinal studies.

Introduction Estimates of the prevalence of chronic pain worldwide and in Canada are inconsistent. Our primary objectives were to determine the prevalence of chronic pain by sex and age and to determine the prevalence of pain-related interference for Canadian men and women between 1994 and 2008. Methods Using data from seven cross-sectional cycles in the National Population Health Survey and the Canadian Community Health Survey, we defined two categorical outcomes, chronic pain and pain-related interference with activities. Results Prevalence of chronic pain ranged from 15.1% in 1996/97 to 18.9% in 1994/95. Chronic pain was most prevalent among women (range: 16.5% to 21.5%), and in the oldest (65 years plus) age group (range: 23.9% to 31.3%). Women aged 65 years plus consistently reported the highest prevalence of chronic pain (range: 26.0% to 34.2%). The majority of adult Canadians who reported chronic pain also reported at least a few activities prevented due to this pain (range: 11.4% to 13.3% of the overall population). Conclusion Similar to international estimates, this Canadian population-based study confirms that chronic pain persists and impacts daily activities. Further study with more detailed definitions of pain and pain-related interference is warranted.

Objectives Our aim in this pilot study was to identify potential predictors of chronic post-surgical pain (CPSP) and other outcomes to consider for inclusion in future prospective studies of CPSP following abdominal gastrointestinal surgery. Methods We followed 76 surgical patients during this prospective single-centre cohort study. Pain characteristics, health-related quality of life (HRQOL), and healthcare utilization were assessed preoperatively, at six weeks postoperatively, and at six months postoperatively. Statistical analyses included descriptive statistics and repeated measures analysis of variance. Results Prior to surgery, 42% of patients reported no pain, 18% reported remote pain, and 33% reported pain at the surgical site. Six months after surgery, 29% of patients with preoperative remote pain and 35% of patients with preoperative pain at the surgical site reported CPSP. Painrelated interference declined from the preoperative to postoperative period; however, six months after surgery almost one-third of participants continued to report painrelated interference with mood (28%), sleep (30%), and enjoyment of life (30%). Consistent with studies of other surgical procedures, measures of anxiety and depression were associated with an increased risk of CPSP. During the six months following surgery, 12% of patients visited the Emergency Department, 15% visited non-traditional providers, and 9.2% visited a walk-in clinic for pain. Compared with Canadian norms, HRQOL was poorer in all domains preoperatively, in all domains but mental health six weeks postoperatively, and in most domains six months postoperatively. Conclusion This feasibility study provides a template for future studies of CPSP following gastrointestinal surgery. Author contributions Elizabeth VanDenKerkhof and WilmaHopman contributed substantially to all aspects of this manuscript, including conception and design; acquisition, analysis, and interpretation of data; drafting the article, and revising the article critically for important intellectual content. Rosemary Wilson contributed substantially to the conception and design of the manuscript. Paul Belliveau and Rosemary Wilson contributed substantially to the acquisition of data. Michelle Reitsma and David Goldstein also contributed to the acquisition of data. Michelle Reitsma contributed to the analysis of data. Paul Belliveau, Rosemary Wilson, and Ian Gilron contributed substantially to the interpretation of data. David Goldstein also contributed to the interpretation of data. Michelle Reitsma contributed to drafting the article. Paul Belliveau, Rosemary Wilson, and Ian Gilron contributed substantially to revising the article critically for important intellectual content. David Goldstein also contributed to revising the article critically for important intellectual content. Results suggest a substantial burden of persistent pain, healthcare utilization, and decreased HRQOL. Largerscale studies that are similarly designed will serve to identify predictors of CPSP in this surgical ...

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