Journal of Rehabilitation Medicine 51-3 | Page 37

J Rehabil Med 2019; 51: 183–192 ORIGINAL REPORT PREDICTORS OF CHRONIC PAIN INTENSITY, SPREAD AND SENSITIVITY IN THE GENERAL POPULATION: A TWO-YEAR FOLLOW-UP STUDY FROM THE SWEPAIN COHORT Britt LARSSON, PhD 1 , Elena DRAGIOTI, PhD 1 , Anna GRIMBY-EKMAN, PhD 2 , Björn GERDLE, PhD 1 and Jonas BJÖRK, PhD 3 From the 1 Pain and Rehabilitation Centre, and Department of Medical and Health Sciences, Linköping University, Linköping, 2 Health Metrics, University of Gothenburg, Gothenburg and 3 Division of Occupational and Environmental Medicine, Lund University, Lund, Sweden Objective: To determine whether the intensity, spread and sensitivity of chronic pain can be pre­ dicted using demographic features, socioeconomic conditions and comorbidities. Design: A longitudinal study design was employed. Data was collected at baseline and at 2-year follow- up. Setting: General population in south-eastern Sweden. Subjects: A representative stratified random sam­ ple of 34,000 individuals, between 18 and 85 years of age, selected from a sampling frame of 404,661 individuals based on the Swedish Total Population Register. Methods: Eligible individuals were sent postal sur­ veys in 2013 and 2015. The 2 surveys included the same questions about basic demographic data, co­ morbidities, and chronic pain intensity, spread and sensitivity. Results: Several socio-demographic features and co­ morbidities at baseline were significant predictors of characteristics of pain (intensity, spread and sensi­ tivity) at the 2-year follow-up. When characteristics of pain at baseline were included in the regression analyses they were relatively strong significant pre­ dictors of characteristics of pain after 2 years. After this adjustment there were fewer socio-demogra­ phic and comorbidity predictors; the effect estimates for those significant predictors had decreased. Conclusion: Clinical assessment should focus on several characteristics of pain and include a broad medical screening to capture the overall burden of pain in adults from a longitudinal perspective. Key words: general population; follow-up; chronic pain cha- racteristics; sociodemographic; comorbidities. Accepted Jan 3, 2019; Epub ahead of print Feb 27, 2019 J Rehabil Med 2019; 51: 183–192 Correspondence address: Britt Larsson, Pain and Rehabilitation Medi- cine, Department of Medical and Health Sciences (IMH), Faculty of Medicine and Health Sciences, Linköping University, SE-581 85 Linkö- ping. E-mail: [email protected] A pproximately 20% of the European population have moderate to severe chronic pain (CP) (> 3 months) (1), hence it is important to elucidate the trajectory of CP and determine which factors affect this trajectory. LAY ABSTRACT This study shows how characteristics of chronic pain (in- tensity, spread and sensitivity) can be predicted using demographic and socioeconomic factors and other med- ical conditions. Information was collected from 34,000 individuals between 18 and 85 years of age in south- eastern Sweden. Several socio-demographic factors and other medical conditions were predictors of pain inten- sity, spread and sensitivity after 2 years. When pain characteristics were taken into consideration in the ana- lysis they were relatively strong predictors of the pain characteristics after 2 years. After modification of the analysis, there were fewer socio-demographic and med- ical predictors and their importance had decreased. In planning treatment and rehabilitation for chronic pain, pain intensity, spread and sensitivity should specifically be taken into account. Longitudinal studies have investigated how CP itself, socio-demographic factors and comorbidities impact CP over time (2–8); however, the results of those studies often do not agree, and do not cover all important characteristics of pain. Some studies have predicted the presence of chronic widespread pain and/or spreading (of pain on the body) (2, 4–6). Other studies have predicted new onset of CP (3). Li- kewise, pain intensity (severity rated by the subject on a numeric scale) and pain sensitivity (increased pain responsiveness to noxious and/or non-noxious stimuli) are important aspects that contribute to the clinical presentation of CP (9, 10). Together with physical and emotional functions, comorbidities, coping strategies, and quality of life aspects, these characteristics of pain should be taken into account when elucidating the impact of pain (11–14). Previous cross-sectional epidemiological studies have found that socio-demographic factors, such as age, sex, marital status, educational level and low income (15, 16), are associated with CP (i.e. duration > 3 months). Recent longitudinal studies have investigated the importance of some comorbidities, e.g. anxiety, de- pression, sleeping difficulties, body mass index (BMI) (2–6), or used an index for comorbidities (4). However, other comorbidities, e.g. heart disease, hypertension, diabetes and pulmonary disease, have also been as- This is an open access article under the CC BY-NC license. www.medicaljournals.se/jrm Journal Compilation © 2019 Foundation of Rehabilitation Information. ISSN 1650-1977 doi: 10.2340/16501977-2519