ORIGINAL ARTICLE
Factors Associated With Disability and Sick Leave in Early Complex Regional Pain Syndrome Type-1 Debbie J. Bean, MSc,*w Malcolm H. Johnson, MA,w Wolfgang Heiss-Dunlop, State Exam Med (Germany),z and Robert R. Kydd, PhDw
Objective: Factors influencing disability and work absence in complex regional pain syndrome type-1 (CRPS)-1 have not been thoroughly described in the literature. We sought to determine whether demographic variables, work-related factors, CRPS clinical severity ratings, pain scores, or psychological variables were associated with disability and sick leave in early CRPS-1. Methods: A total of 66 CRPS-1 patients were recruited within 12 weeks of CRPS onset. Patients completed measures of pain, depression, anxiety, stress, pain catastrophizing, and pain-related fear. A physical examination was conducted to assess signs and symptoms of CRPS and to calculate a CRPS severity score. Demographic details, clinical details, treatments, work type, and work status were recorded. Results: In multivariate analyses, the following factors were associated with greater disability: higher pain scores, more restricted ankle or wrist extension, and higher levels of depression. Among the 49 who were either working or studying before developing CRPS, 28 had stopped work or study at the time of assessment. Multivariate analyses showed that sick leave was more likely among those whose CRPS was triggered by more severe injuries, whose work was more physically demanding, among those with higher disability scores, and there was also a significant effect of depression on sick leave, which was mediated by disability. Discussion: Although the study was cross-sectional and so cannot differentiate cause from effect, results suggest that even in the early stages of CRPS, a cycle of pain, disability, depression, and work absence can emerge. Treatments aimed to prevent this cycle may help prevent adverse long-term outcomes. Key Words: complex regional pain syndrome type-1, work, psychological factors, disability, depression
(Clin J Pain 2016;32:130–138)
C
omplex regional pain syndrome type-1 (CRPS-1) is a condition that can occur after fracture, surgery, minor
Received for publication June 5, 2014; revised April 15, 2015; accepted March 1, 2015. From *The Auckland Regional Pain Service (TARPS), Auckland District Health Board; wDepartment of Psychological Medicine, The University of Auckland; and zAuckland Regional Plastic Reconstructive & Hand Surgery Service, Counties Manukau District Health Board, Auckland, New Zealand. Supported by the Oakley Mental Health Research Foundation, Auckland, New Zealand. The authors declare no conflict of interest. Reprints: Debbie J. Bean, MSc, The Auckland Regional Pain Service, Auckland District Health Board, Private Bag 92189, Auckland Mail Centre, Auckland 1142, New Zealand (e-mail: [email protected]). Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Website, www. clinicalpain.com. Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/AJP.0000000000000234
injury, stroke, or spontaneously. It usually affects either the upper or lower limb, and symptoms include pain, allodynia, hyperalgesia, changes to skin color and limb temperature, swelling, alterations to hair and nail growth, altered sweating, reduced range of movement, and motor changes such as weakness, tremor, or dystonia. Previous studies have shown that the clinical outcomes of CRPS can vary considerably,1 and while some studies show that the majority of patients make a good recovery,2 some patients develop lasting symptoms.3 Very few studies have explored disability in CRPS patients but those that have suggest that CRPS patients can develop long-term disability. For example, Subbarao and Stillwell4 reported that only 30% of CRPS patients were able to resume 100% of their normal activities, even at 2year follow-up. Similarly, Savas et al5 found statistically significant limitations on 6 of the 8 dimensions of the SF-36 when comparing CRPS patients to healthy controls, 18 months after treatment. We found only 2 published studies that assessed factors which might predict disability. de Jong et al6 found that among those with chronic CRPS, patients who had higher pain-related fear (measured on a pictorial assessment tool) were more disabled, even after controlling for pain intensity. Interestingly, in both this chronic sample, and in an acute CRPS sample, pain-related fear, when measured by a questionnaire, did not predict disability above and beyond pain intensity.6 This might be due to limitations in the measurement tool used, or might reflect that different processes influence disability at different timepoints in the course of CRPS. Psychological variables such as pain-related fear, pain catastrophizing, depression, and anxiety have been shown to predict disability in other pain conditions (eg, low back pain),7 and we previously found that depression had a stronger association with disability in a sample of chronic CRPS patients compared with low back pain patients.8 Because of the relatively limited range of research that has been conducted early in the course of CRPS, and the potential for intervening at this time, we aimed to identify whether pain-related fear, as well as other psychological factors, influence disability in the first 3 months after the onset of CRPS. For the purposes of this study, the term “disability” was operationalized to indicate not just physical impairments, but to encompass limitations in a broad range of life roles, including recreational, social, household, sexual, self-care, and occupational activities. We also aimed to assess the influence of psychological factors on work status separately. Previous studies have demonstrated that CRPS leads to sick leave and long-term work disability in a significant proportion of patients. For example, Subbarao and Stillwell4 reported that 3 years after developing CRPS around a third of patients were officially disabled, a third
130 | www.clinicalpain.com Clin J Pain Volume 32, Number 2, February 2016 Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
Clin J Pain
Volume 32, Number 2, February 2016
either retired or did not return to the same job, and a third were back to their previous job. Similarly, de Mos et al3 reported that 41% of CRPS patients resumed their normal work, 28% adapted their work, and 31% stopped work altogether. Duman et al9 reported on work outcomes for military personnel with CRPS who were all men, with a mean age of 23 years: 28% became officially disabled due to CRPS. Only 2 previous studies assessed predictors of work status among CRPS patients. The first found return to work was associated with younger age, a sedentary job, upper limb involvement, a higher level of education, and early analgesic treatment associated with physiotherapy.10 The second reported that among 16 CRPS patients, return to work was quicker for those with a sedentary job, those whose CRPS started with a less serious injury, affected a proximal joint (eg, shoulder, knee) rather than distal joint (eg, wrist/ankle) and when the injury did not occur at work. The study was too small to conduct multivariate analyses or to determine which of these variables were independent predictors. It also reported that several patients did not get back to work due to psychological problems such as chronic alcoholism or depression.11 Sandroni et al12 found that 46% of CRPS patients did not claim any disability status, and 15% of these patients had not experienced “symptom resolution,” which suggests that some patients with CRPS are able to continue working despite ongoing symptoms, while others are not. As yet no studies have assessed the role of pain intensity or psychosocial variables in predicting the work status of CRPS patients. Psychosocial variables have been shown to predict work status in other pain conditions, so may be worthwhile exploring in CRPS.13 Previous research has shown that having pain patients either stay at work or return to work early is important. For example, one study of low back pain patients found the chances of return to work are relatively high within the first 6 to 12 weeks (approximately 70% to 75% had a successful or partially successful return to work), but these rates remain near constant at 1- and 2-year follow-ups (approximately 20% were off work at 2 y).14 Identifying risk factors for those likely to go off work during these early stages could be valuable. Thus, the present study, which recruited patients within 12 weeks of CRPS onset, aimed to assess the differences between those who stay at work, and those who stop work, and are therefore at risk of long-term sickness absence.15
Disability and Sick Leave in Early CRPS-1
reported symptoms during a telephone call, 1 lived outside the study area and thus was not covered by ethics approval, and 1 had a previous history of CRPS). Two declined to participate, leaving 67 who consented to the study. Following participation, a further participant was excluded as it was clear her symptoms had been present for longer than 12 weeks. This left a total of 66 participants.
Procedure The study was approved by the New Zealand Ministry of Health Northern Y Ethics Committee. Participants were recruited and seen for a 60- to 90-minute assessment, which consisted of the following measures: (1) CRPS Severity Score/Signs and symptoms of CRPS: this was based on the tool described by Harden et al17 although specific details of the procedure for measuring signs during the physical examination were not available. For each of the following, participants were asked whether they experienced the symptom (excluding hyperpathia), and the primary author examined the affected and unaffected limbs for signs as described below: (a) Color asymmetry: determined by visual inspection, scored none, mild, moderate, or severe. (b) Trophic changes to hair and nails: determined by visual inspection, scored none, mild, moderate, or severe. (c) Sweating asymmetry: determined by visual inspection, scored none, mild, moderate, or severe. (d) Temperature asymmetry: bilateral temperature measured at 5 predefined points over the affected and unaffected limbs using a digital infrared thermometer. (e) Edema: determined by a visual inspection and scored none, mild, moderate, or severe. (f) Motor changes: determined by visual inspection of rapid movement of bilateral fingers/toes, scored none, mild, moderate, or severe (g) Range of motion: wrist or ankle flexion and extension measured bilaterally using goniometer. (h) Allodynia to brush: scored nil, mild, moderate, or severe. (i) Hyperpathia to repetitive tap: present or absent. Severity scores for each of the signs of CRPS were utilized, and in addition this information was used to calculate a CRPS Severity Score. This was calculated by summing the number of symptoms reported by the patient (out of a total of 8) and the number of signs observed (out of a total of 9), to give a total score out of 17. Higher scores represent more severe cases of CRPS. This scale has been shown to have good sensitivity to discriminate between CRPS and non-CRPS patients, and provides greater sensitivity to change compared with measuring CRPS as either present or absent.17
METHODS Participants The participants were patients with newly onset upper or lower limb CRPS type-1 referred to the study from orthopedic, plastic surgery, hand therapy, physiotherapy, and pain clinics in Auckland, New Zealand between February 2012 and January 2014. Inclusion criteria were: (1) meets the 1994 IASP criteria for CRPS16; (2) CRPS for
Factors Associated With Disability and Sick Leave in Early Complex Regional Pain Syndrome Type-1 Debbie J. Bean, MSc,*w Malcolm H. Johnson, MA,w Wolfgang Heiss-Dunlop, State Exam Med (Germany),z and Robert R. Kydd, PhDw
Objective: Factors influencing disability and work absence in complex regional pain syndrome type-1 (CRPS)-1 have not been thoroughly described in the literature. We sought to determine whether demographic variables, work-related factors, CRPS clinical severity ratings, pain scores, or psychological variables were associated with disability and sick leave in early CRPS-1. Methods: A total of 66 CRPS-1 patients were recruited within 12 weeks of CRPS onset. Patients completed measures of pain, depression, anxiety, stress, pain catastrophizing, and pain-related fear. A physical examination was conducted to assess signs and symptoms of CRPS and to calculate a CRPS severity score. Demographic details, clinical details, treatments, work type, and work status were recorded. Results: In multivariate analyses, the following factors were associated with greater disability: higher pain scores, more restricted ankle or wrist extension, and higher levels of depression. Among the 49 who were either working or studying before developing CRPS, 28 had stopped work or study at the time of assessment. Multivariate analyses showed that sick leave was more likely among those whose CRPS was triggered by more severe injuries, whose work was more physically demanding, among those with higher disability scores, and there was also a significant effect of depression on sick leave, which was mediated by disability. Discussion: Although the study was cross-sectional and so cannot differentiate cause from effect, results suggest that even in the early stages of CRPS, a cycle of pain, disability, depression, and work absence can emerge. Treatments aimed to prevent this cycle may help prevent adverse long-term outcomes. Key Words: complex regional pain syndrome type-1, work, psychological factors, disability, depression
(Clin J Pain 2016;32:130–138)
C
omplex regional pain syndrome type-1 (CRPS-1) is a condition that can occur after fracture, surgery, minor
Received for publication June 5, 2014; revised April 15, 2015; accepted March 1, 2015. From *The Auckland Regional Pain Service (TARPS), Auckland District Health Board; wDepartment of Psychological Medicine, The University of Auckland; and zAuckland Regional Plastic Reconstructive & Hand Surgery Service, Counties Manukau District Health Board, Auckland, New Zealand. Supported by the Oakley Mental Health Research Foundation, Auckland, New Zealand. The authors declare no conflict of interest. Reprints: Debbie J. Bean, MSc, The Auckland Regional Pain Service, Auckland District Health Board, Private Bag 92189, Auckland Mail Centre, Auckland 1142, New Zealand (e-mail: [email protected]). Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Website, www. clinicalpain.com. Copyright r 2015 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/AJP.0000000000000234
injury, stroke, or spontaneously. It usually affects either the upper or lower limb, and symptoms include pain, allodynia, hyperalgesia, changes to skin color and limb temperature, swelling, alterations to hair and nail growth, altered sweating, reduced range of movement, and motor changes such as weakness, tremor, or dystonia. Previous studies have shown that the clinical outcomes of CRPS can vary considerably,1 and while some studies show that the majority of patients make a good recovery,2 some patients develop lasting symptoms.3 Very few studies have explored disability in CRPS patients but those that have suggest that CRPS patients can develop long-term disability. For example, Subbarao and Stillwell4 reported that only 30% of CRPS patients were able to resume 100% of their normal activities, even at 2year follow-up. Similarly, Savas et al5 found statistically significant limitations on 6 of the 8 dimensions of the SF-36 when comparing CRPS patients to healthy controls, 18 months after treatment. We found only 2 published studies that assessed factors which might predict disability. de Jong et al6 found that among those with chronic CRPS, patients who had higher pain-related fear (measured on a pictorial assessment tool) were more disabled, even after controlling for pain intensity. Interestingly, in both this chronic sample, and in an acute CRPS sample, pain-related fear, when measured by a questionnaire, did not predict disability above and beyond pain intensity.6 This might be due to limitations in the measurement tool used, or might reflect that different processes influence disability at different timepoints in the course of CRPS. Psychological variables such as pain-related fear, pain catastrophizing, depression, and anxiety have been shown to predict disability in other pain conditions (eg, low back pain),7 and we previously found that depression had a stronger association with disability in a sample of chronic CRPS patients compared with low back pain patients.8 Because of the relatively limited range of research that has been conducted early in the course of CRPS, and the potential for intervening at this time, we aimed to identify whether pain-related fear, as well as other psychological factors, influence disability in the first 3 months after the onset of CRPS. For the purposes of this study, the term “disability” was operationalized to indicate not just physical impairments, but to encompass limitations in a broad range of life roles, including recreational, social, household, sexual, self-care, and occupational activities. We also aimed to assess the influence of psychological factors on work status separately. Previous studies have demonstrated that CRPS leads to sick leave and long-term work disability in a significant proportion of patients. For example, Subbarao and Stillwell4 reported that 3 years after developing CRPS around a third of patients were officially disabled, a third
130 | www.clinicalpain.com Clin J Pain Volume 32, Number 2, February 2016 Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.
Clin J Pain
Volume 32, Number 2, February 2016
either retired or did not return to the same job, and a third were back to their previous job. Similarly, de Mos et al3 reported that 41% of CRPS patients resumed their normal work, 28% adapted their work, and 31% stopped work altogether. Duman et al9 reported on work outcomes for military personnel with CRPS who were all men, with a mean age of 23 years: 28% became officially disabled due to CRPS. Only 2 previous studies assessed predictors of work status among CRPS patients. The first found return to work was associated with younger age, a sedentary job, upper limb involvement, a higher level of education, and early analgesic treatment associated with physiotherapy.10 The second reported that among 16 CRPS patients, return to work was quicker for those with a sedentary job, those whose CRPS started with a less serious injury, affected a proximal joint (eg, shoulder, knee) rather than distal joint (eg, wrist/ankle) and when the injury did not occur at work. The study was too small to conduct multivariate analyses or to determine which of these variables were independent predictors. It also reported that several patients did not get back to work due to psychological problems such as chronic alcoholism or depression.11 Sandroni et al12 found that 46% of CRPS patients did not claim any disability status, and 15% of these patients had not experienced “symptom resolution,” which suggests that some patients with CRPS are able to continue working despite ongoing symptoms, while others are not. As yet no studies have assessed the role of pain intensity or psychosocial variables in predicting the work status of CRPS patients. Psychosocial variables have been shown to predict work status in other pain conditions, so may be worthwhile exploring in CRPS.13 Previous research has shown that having pain patients either stay at work or return to work early is important. For example, one study of low back pain patients found the chances of return to work are relatively high within the first 6 to 12 weeks (approximately 70% to 75% had a successful or partially successful return to work), but these rates remain near constant at 1- and 2-year follow-ups (approximately 20% were off work at 2 y).14 Identifying risk factors for those likely to go off work during these early stages could be valuable. Thus, the present study, which recruited patients within 12 weeks of CRPS onset, aimed to assess the differences between those who stay at work, and those who stop work, and are therefore at risk of long-term sickness absence.15
Disability and Sick Leave in Early CRPS-1
reported symptoms during a telephone call, 1 lived outside the study area and thus was not covered by ethics approval, and 1 had a previous history of CRPS). Two declined to participate, leaving 67 who consented to the study. Following participation, a further participant was excluded as it was clear her symptoms had been present for longer than 12 weeks. This left a total of 66 participants.
Procedure The study was approved by the New Zealand Ministry of Health Northern Y Ethics Committee. Participants were recruited and seen for a 60- to 90-minute assessment, which consisted of the following measures: (1) CRPS Severity Score/Signs and symptoms of CRPS: this was based on the tool described by Harden et al17 although specific details of the procedure for measuring signs during the physical examination were not available. For each of the following, participants were asked whether they experienced the symptom (excluding hyperpathia), and the primary author examined the affected and unaffected limbs for signs as described below: (a) Color asymmetry: determined by visual inspection, scored none, mild, moderate, or severe. (b) Trophic changes to hair and nails: determined by visual inspection, scored none, mild, moderate, or severe. (c) Sweating asymmetry: determined by visual inspection, scored none, mild, moderate, or severe. (d) Temperature asymmetry: bilateral temperature measured at 5 predefined points over the affected and unaffected limbs using a digital infrared thermometer. (e) Edema: determined by a visual inspection and scored none, mild, moderate, or severe. (f) Motor changes: determined by visual inspection of rapid movement of bilateral fingers/toes, scored none, mild, moderate, or severe (g) Range of motion: wrist or ankle flexion and extension measured bilaterally using goniometer. (h) Allodynia to brush: scored nil, mild, moderate, or severe. (i) Hyperpathia to repetitive tap: present or absent. Severity scores for each of the signs of CRPS were utilized, and in addition this information was used to calculate a CRPS Severity Score. This was calculated by summing the number of symptoms reported by the patient (out of a total of 8) and the number of signs observed (out of a total of 9), to give a total score out of 17. Higher scores represent more severe cases of CRPS. This scale has been shown to have good sensitivity to discriminate between CRPS and non-CRPS patients, and provides greater sensitivity to change compared with measuring CRPS as either present or absent.17
METHODS Participants The participants were patients with newly onset upper or lower limb CRPS type-1 referred to the study from orthopedic, plastic surgery, hand therapy, physiotherapy, and pain clinics in Auckland, New Zealand between February 2012 and January 2014. Inclusion criteria were: (1) meets the 1994 IASP criteria for CRPS16; (2) CRPS for
