Longitudinal 7-year follow-up of chronic pain in persons with multiple sclerosis in the community Fary Khan, Bhasker Amatya & Jürg Kesselring
Journal of Neurology Official Journal of the European Neurological Society ISSN 0340-5354 J Neurol DOI 10.1007/s00415-013-6925-z
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Author's personal copy J Neurol DOI 10.1007/s00415-013-6925-z
ORIGINAL COMMUNICATION
Longitudinal 7-year follow-up of chronic pain in persons with multiple sclerosis in the community Fary Khan • Bhasker Amatya • Ju¨rg Kesselring
Received: 6 February 2013 / Revised: 8 April 2013 / Accepted: 10 April 2013 Ó Springer-Verlag Berlin Heidelberg 2013
Abstract The aim of this work is to examine the course and impact of chronic pain and pain-related disability in persons with multiple sclerosis (pwMS) over a 7-year period in the Australian community employing a longitudinal, cross-sectional study using structured interviews and validated measures. The intensity of chronic pain was assessed with the visual analogue scale (VAS); the chronic pain grade (CPG) classified pain severity using scores for both pain intensity and pain-related disability, and the assessment of quality of life (AQoL) questionnaire assessed impact on participatory domains. Of the 74 pwMS assessed at 7-year follow-up (T2), 53 (71.6 %) were female, with average age of 55.6 years, and median time since diagnosis of 16.5 years. At T2, 13 (13.8 %) more participants reported chronic pain compared with baseline assessment (T1), (61 vs. 74). Although there were no significant differences on average pain intensity rating between T1 and T2 (p = 0.65), more participants at T2 reported higher rates of pain (13.1 vs. 28.4 %). At T2,
F. Khan (&) B. Amatya Department of Rehabilitation Medicine, Royal Melbourne Hospital, 34-54 Poplar Road Parkville, Melbourne, VIC 3052, Australia e-mail:
[email protected] F. Khan Department of Medicine, Dentistry and Health Sciences, University of Melbourne, Melbourne, VIC, Australia F. Khan School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia J. Kesselring Department of Neurology and Neurorehabilitation, Rehabilitation Center, Valens, Switzerland
participants reported greater disability limiting their daily activities due to pain (16.2 vs. 0 %), and more deterioration and dependency suggested by the AQoL domains of ‘‘Independent living’’ (p \ 0.001) and ‘‘Physical senses’’ (p = 0.013). At T2, pwMS used less pharmacological medication but accessed more ‘‘other’’ therapy to cope with their chronic pain. This study provides longitudinal insight into the complex multidimensional chronic pain-related disability in pwMS over a longer period. Improved clinician understanding of the course of chronic pain, early intervention, and patient self-management may decrease pain-related disability and contribute to their overall wellbeing. Keywords Multiple sclerosis Rehabilitation Chronic pain Quality of life Disability
Introduction Pain is commonly experienced by persons with multiple sclerosis (pwMS) and can be a significant health problem [1, 2]. Multiple sclerosis (MS)-related pain may be both acute and/or chronic and associated with active inflammation of the MS process itself (e.g., pain associated with optic neuritis and neuralgia), and from protracted symptoms and complications of MS (e.g., pain caused by painful muscle contractures/spasm and stiffened joints, gait anomalies, trigeminal neuralgia, spasms) [3, 4]. The reported prevalence of pain in MS literature ranges from 23 to 90 % [5, 6]. This variability can be explained by discrepancies in the methods employed in studies, sample sizes, and characteristics and outcome measures used [1, 5, 7, 8]. There is evidence demonstrating the negative impact of pain on activities of daily living, relationships and social
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role in pwMS [6, 9–11]; associated with poorer general health and increased fatigue resulting in higher rates of health care utilization [6, 12–14]. Pain impacts working age MS population and causes social disadvantage [8, 15, 16]. Studies of chronic pain in pwMS in the community [17, 18] showed that those in higher pain grades [19] reported greater disability, more health care visits, and a lower quality of life (QoL) [17]. Other studies suggest that prevalence of chronic pain problems increase over time, may interfere with work [9], and are associated with increased psychological symptoms [1, 20]. Evidence for long-term follow-up of pain among pwMS is limited. One previous study reported an increase in the frequency of MS-related pain syndromes over time, with the percentage of patients who experience pain increasing from 53 to 86 % over a 5-year period [21]. Although several studies report the psychosocial aspects of acute and chronic pain in pwMS [17, 18, 21], there is limited information about the long-term course of MSrelated pain or its impact on psychosocial functioning, daily activities, and QoL in the Australian context. Therefore, this study examined the course of MS-related pain over the longer term and assessed the characteristics of chronic pain, treatments, and pain-related disability (functional outcomes and psychosocial sequelae) in pwMS in a community cohort.
Materials and methods Participants and setting This prospective, cross-sectional longitudinal study was part of a rehabilitation outcomes research program for pwMS at the Royal Melbourne Hospital (RMH), a tertiary referral center in Victoria, Australia; and approved by its Research committee (HREC No. 2009.035). Participant recruitment process has been previously described [17]. The source of participants was from the RMH MS database, which recruited patients through the MS society, and public and private neurology clinics across greater Melbourne. The MS database contained detailed patient information including: demographic data, diagnosis details (using McDonald criteria) [25], stage of disease, and severity category using Expanded Disability Status Scale (EDSS) levels [22]. The participants for the present study were recruited from an initial cohort of pwMS from the RMH MS database in 2005 (n = 101) [17]. All participants were aged [18 years, resided in the community (area of greater Melbourne \60 km radius), fulfilled standard McDonald diagnostic criteria [23], and had known limitations in neurological disability including mobility and cognition
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based on Kurtzke’s Functional Systems (KFS) and the EDSS scores [22]. These included EDSS scores for mobility in the range of 2–8, and cognition scores between 0 and 2. The exclusion criteria included: cognition scores greater than two on the KFS, significant co-morbidities (medically unstable such as brittle diabetes mellitus, unstable angina), or unstable psychiatric disorders (such as uncontrolled schizophrenia, actively suicidal/self-harm or physically aggressive (based on clinical judgment)). Those with depression were not excluded. Patients who were bedbound and/or institutionalized in nursing homes and not fulfilling the criteria of chronic pain at the time of the assessment were excluded. Data collection All eligible participants (n = 94) who participated in the baseline interview in 2005 [17] were contacted by mail and invited to participate for the follow-up assessment by an independent research officer. Of these, 74 consecutive participants, who complied with the definition and criteria for chronic pain, were recruited for the follow-up. A faceto-face structured interview technique was used, for a more definitive clinical evaluation and accurate self-report. All interviews (45 min each) were conducted by an independent trained research officer (in clinic or participants’ homes) using a structured format using standardized instruments (see ‘‘Measures’’). The assessors did not prompt participants, but provided assistance for those who have difficulty with completing the questionnaires. Appropriate rest breaks were provided during these interviews. All assessments were secured and filed, and opened at the time of entry into the database by an independent data entry officer. Measurement Similar to the assessment conducted at baseline in 2005 [17], pain was assessed by using temporal criteria (chronic) as well as a symptom-oriented approach, using a structured questionnaire and interview. Chronic pain was defined as (constant or intermittent) pain experienced every day for 3 months in the 6 months before interview [24]. All reported pain that fulfilled study criteria was included and guidelines for classification of pain were used for neuropathic pain (trigeminal neuralgia, Lhermittes sign, dysesthetic pain), somatic pain (back pain and painful tonic spasms), or visceral pain [25]. MS-related measures Participants demographic details and information about MS symptom onset and diagnosis, EDSS scores, and stage
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of disease (classified as relapsing remitting (RR), secondary progressive (SP), and primary progressive (PP)) were obtained from the RMH MS database. The severity of MS was determined by assigning a score for each of the seven KFS (pyramidal, cerebellar, brain stem, sensory, bowel and bladder, visual, cerebral) and a single unifying score of the EDSS [22] quantifying disability from the seven functional system scores. EDSS is a 20-step scale (using half steps) ranging from 0 (normal) to 10 (death due to MS). The participants with MS were divided into three groups: Mild (EDSS: 0–3), moderate (EDSS: 3.5–6.0), and severe (EDSS: 6.5–8). Pain measures Comprehensive information on pain was collected, which included: characteristics of pain, duration of pain (in years), quality of pain (such as aching, dull, burning), temporal aspects of pain, trigger factors, site of pain (using pain diagram-figure drawings of front/back) and impact of pain-related disability and social role performance. The severity of pain was assessed using the 10-point numerical rating scale (0 = no pain and 10 = pain as bad as could be) [7, 26], while the descriptive pain scale (with the Likert scale of 0–6 (0 = no pain, 6 = worst possible pain)) described the pain. The severity of chronic pain was classified using the chronic pain grade (three items about pain intensity and four about pain-related disability) [19]. The pain intensity items was assessed using a 10-point numerical rating scale, where zero is ‘‘no pain’’ and ten is ‘‘pain as bad as could be’’ and included: (1) How would you rate your back/headache/facial pain at the present time? (2) In the past 6 months, how intense was your worst pain? (3) In the past 6 months, on average, how intense was your pain? Similarly, the disability items were scored on a 10-point numerical rating scale, where zero is ‘‘no interference/problem’’ and ten is ‘‘worst problem/extreme interference’’ and included: (4) In the past 6 months, how much has back/headache/facial pain interfered with your daily activities? (5) In the past 6 months, how much has back/headache/facial pain changed your ability to take part in recreational, social, and family activities, change, and 10 is ‘‘extreme change’’? (6) In the past 6 months, how much has back/headache/facial pain changed your ability to work (including house work)? (7) About how many days in the last 6 months have you been kept away from your usual activities (work, school, or house work) because of back/ headache/facial pain? (disability days). The scoring for grading chronic pain severity was conducted as follows: characteristic pain intensity, a 0–100 score derived from questions one through three (above): mean for items (pain right now, worst pain, average pain 9 10). The disability score (0–100 score) was derived
from questions four through six: Mean (daily activities, social activities, work activities 9 10). For disability points, indicated points for disability days (question seven) were added and for disability score a mathematical formula of von Korff was used [19]. Based on these scores, the participants were then classified to grade 0 (no pain), grade I (low disability–low intensity), grade II (low disability– high intensity), grade III (high disability–moderately limiting), and grade IV (high disability–severely limiting) [19]. Measurement of pain treatments and access Medication used for pain (both current and those used in the previous 6 months) were documented, and classified using categories from the monthly index of medical specialties Australia (MIMS Australia) [27]. The participants were asked to indicate their usual pain-management methods across the categories of medication, physical/ mechanical/temperature manipulation, rest/sleep exercise, distraction, or alternative techniques [28]. Further, information on perceived barriers and access to health care, the number and frequency of visits in the last 12 months to medical practitioners, allied health professionals, and alternative practitioners for pain management were recorded. Measures of QoL The assessment of quality of life (AQoL) scale [29], a generic utility measure assessed health-related QoL (HRQoL) in four domains: independent living, social relationships, physical senses, and psychological wellbeing. The utility values for each subscale range between -0.04 (representing state worse than death) and 1.00 (best possible health state). An overall utility score, extending from –0.04 (worst possible HRQoL state) to 1.00 (full HRQoL), were calculated by summing scores form the four dimensions. AQoL has been validated for use in a range of patient groups and by a range of delivery procedures [30, 31]. Statistical methods All analyses performed were consistent with the procedures adopted in our baseline study [17]. Descriptive statistics (median, IQR and %, n for categorical data) described the prevalence and characteristics of the pain experienced, the utilization of health services, perceived barriers to treatment, and pain management techniques used by pwMS. Due to the relatively small group sizes and the skewed distribution, non-parametric statistical analyses (Mann– Whitney U test, Kruskal–Wallis test, v2 test) compared
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participants across various chronic pain grades. AQoL utility scores were calculated according to guidelines [30, 31]. Wilcoxon signed-rank test compared scores between T1 and T2 for subscales of the AQoL. Spearman correlation coefficients were calculated to assess the relationship between pain intensity and AQoL subscales. All calculations were performed using IBM SPSS for Windows (version 21.0). Statistical significance was determined by a level of \0.05.
Results The sample assessed at 7-year follow-up (T2) (n = 74) consisted of 53 (71.6 %) female participants, with average age of 55.6 ± 8.7 (range, 35.0–71.0 years), and median time since diagnosis of 16.5 years (inter-quartile range, 12.0–22.0 years). The reported range of disease severity amongst participants varied: with 14 (18.9 %) in group 1 (EDSS: 0–3), 42 (56.8 %) in group 2 (EDSS: 3.5–6.0), and 18 (24.3 %) in group 3 (EDSS: 6.5 and above). More than half of the participants (n = 46, 62.2 %) had SP MS, 19 (25.7 %) had RR MS, and nine (12.2 %) had PP MS (Table 1). Of the 94 eligible participants from the dataset, 74 (79 %) who fulfilled the definition and criteria of chronic pain were assessed for the follow-up assessments (T2). Of these five deceased, two were unable to be located, two declined, and 11 reported not having pain (therefore did not fulfill study criteria for chronic pain).
Chronic pain prevalence and characteristics Prevalence, location, type, and intensity of pain at baseline (T1) and at follow-up (T2) are listed in Table 2. At T2, 13 (13.8 %) more participants reported chronic pain since baseline (T1) assessment (61 (65 %) vs. 74 (79 %)). The most common pain location was in the lower limbs with more than half (53 %) reporting bilateral pain and a further 18 % reporting unilateral pain in this area. At T2, lesser participants reported dysesthetic pain (60.7 vs. 48.6 %), but nociceptive pain increased considerably (6.6 vs. 87.8 %). Although the participants reported chronic pain intensity (using VAS) at T2 to be lower, the differences on average pain intensity rating between T1 and T2 were not statistically significant (5.2 ± 2.1 vs. 5.3 ± 2.5, p = 0.65). Compared with T1, at T2 more participants reported a higher rate of pain (severe to worst pain) (28.4 vs. 13.1 %). Chronic pain grade The chronic pain grade (CPG) classified chronic pain severity, based on scores for items on pain intensity and pain-related disability (see ‘‘Measures’’). As expected, at T2 more participants reported higher disability, severely limiting their daily activities due to pain (grade IV–high disability, severely limiting, 16.2 vs. 0 %). At T2, 34 participants (46 %) were classified as grade I (low disability, low intensity), 24 (32 %) in grade II (low disability, high intensity), and 4 (5 %) in grade III (high disability, moderately limiting), compared to 21 (34 %), 25 (41 %), and 13 (21 %) at T1, respectively (Table 3). Pain-management techniques and health service utilization
Table 1 Socio-demographic characteristics of participants (n = 74) Characteristics
n (%) (unless stated different)
Age (years) [mean (SD), range]
55.6 (8.7), 35.0–71.0
Sex female Living with
53 (71.6)
Alone
21 (28.4)
Partner/family
53 (71.6)
Disease duration (years) [Md, (IQR)]
16.5 (12.0, 22.0)
EDSS group Group I (EDSS 0–3)
14 (18.9)
Group II (EDSS 3.5–6)
42 (56.8)
Group III (EDSS 6.5?)
18 (24.3)
MS type Relapsing-remitting (RR)
19 (25.7)
Secondary progressive (SP)
46 (62.2)
Primary progressive (PP)
Perceived barriers to health care
9 (12.2)
EDSS expanded disability status scale, IQR inter-quartile range, Md median, MS multiple sclerosis, n total number, SD standard deviation
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At T2, more participants seem to be embarking on physical activities than medication usage (Table 4). The most commonly reported pain-management techniques included physical/electrical manipulation (54 %), rest/sleep (46 %), and exercise (43 %). Utilization of health services is detailed in Table 5, showing the percentage of participants who used each service. Compared with T1, there was an increase in overall consultations with the healthcare professionals at T2, where a higher number of participants consulted a neurologist (62 vs. 48 % at T1), rehabilitation physician (22 vs. 12 %), pain specialist (11 vs. 3 %), surgeon (5 vs. 2 %); and visited a physiotherapist (49 vs. 35 % at T1), and an acupuncturist (23 vs. 13 %) (Table 5).
Participants reported no change at T2 in the perceived barriers in accessing treatment for their pain for both
Author's personal copy J Neurol Table 2 Characteristics and descriptors of chronic pain, intensity, and frequency
T1 (baseline) (n = 61) n (%)
T2 (7-year follow-up) (n = 74) n (%)
Location Head–Unilateral
7 (11.5)
8 (10.8)
Head–Bilateral
10 (16.4)
12 (16.2)
Limbs–Upper unilateral
13 (21.3)
18 (24.3)
Limbs–Upper bilateral
8 (13.1)
7 (9.5)
Limbs–Lower unilateral
11 (18.0)
13 (17.6)
Limbs–Lower bilateral
26 (42.6)
39 (52.7)
Trunk unilateral
8 (13.1)
12 (16.2)
Trunk bilateral
20 (32.8)
16 (21.6)
17 (27.9) 33 (54.1)
24 (32.4) 29 (39.2)
5 (8.2)
16 (21.6)
Descriptive pain intensity scale Mild pain Moderate pain Severe pain Very severe pain
2 (3.3)
3 (4.1)
Worst possible pain
1 (1.6)
2 (2.7)
Intensity Constant intensity
25 (41.0)
27 (36.5)
Episodic increase
43 (70.5)
46 (62.2)
Increase with time
22 (36.1)
16 (21.6)
Increase by physical activity
33 (54.1)
21 (28.4)
Constant pain
35 (57.4)
37 (50.0)
10 years
47 (77.0)
47 (63.5)
10–20 years
14 (23.0)
23 (31.1)
Duration
21–30 years 30 years Temporal aspects of pain Onset before other symptoms Onset same year as other symptoms
0 (0)
4 (5.4)
0 (0)
0 (0)
12 (20.0)
12 (16.2)
6 (10.0)
9 (12.2)
Onset 1–5 years before other symptoms
16 (26.7)
16 (21.6)
Onset 6–10 years after other symptoms
9 (15.0)
11 (14.9)
17 (28.3)
26 (35.1)
1 (1.7)
4 (5.4)
Onset 10 years after other symptoms Quality of pain Superficial Deep
46 (76.7)
58 (78.4)
Superficial and deep
13 (21.7)
12 (16.2)
Aching
34 (55.7)
38 (51.4)
Burning
21 (35.0)
20 (27.0)
Pricking
9 (14.8)
10 (13.5)
Pain description
Stabbing
26 (42.6)
23 (31.1)
Throbbing Squeezing/cramping
25 (41.0) 35 (57.4)
14 (18.9) 24 (32.4)
Numbness/heightening
24 (39.3)
15 (20.3)
Itching/prickling
20 (32.8)
7 (9.5)
7 (11.5)
2 (2.7)
Pain to light touch
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T1 (baseline) (n = 61) n (%) Increased sensitivity to ordinary touch
T2 (7-year follow-up) (n = 74) n (%)
6 (9.8)
1 (1.4)
30 (49.2)
21 (28.4)
One pain quality
5 (8.5)
17 (23.0)
Two pain quality
14 (23.7)
27 (36.5)
Three pain quality
7 (11.9)
14 (18.9)
33 (54.0)
16 (21.6)
Pain with movement Number of pain qualities
Four or more pain quality a
Burning, numbness, itching, pricking, pain to light touch, increased sensitivity to touch
b
Aching, dull, stabbing, throbbing, squeezing, cramping, pain on movement
Types of pain Dysesthetic paina
37 (60.7)
36 (48.6)
Nociceptive painb
4 (6.6)
65 (87.8)
Trigeminal neuralgia Painful tonic spasms and back pain
4 (6.6) 33 (54.1)
8 (10.8) 27 (36.5)
Headache
13 (21.3)
7 (9.5)
n = total number
environmental and cognitive/communication barriers. The most commonly reported environmental barrier at both T1 and T2 was lack of finances. At T1, participants reported various ‘‘other’’ difficulties and issues for getting their pain treated (such as ‘‘nothing works for pain, so they do not mention it (33 %), fear of taking medication (16 %), side effects from medication (15 %)). At T2, none of these difficulties were mentioned by the participants’’, suggesting many developed adaptation and/or coping strategies for persisting pain (Table 6). Quality of life Compared with participant report at T1, there was a significant deterioration in scores at T2 for AQoL domains of ‘‘independent living’’ (p \ 0.001) and ‘‘physical senses’’ (p = 0.013) (Table 7). Participants with chronic pain were compared across the different chronic pain grade classifications for AQoL subscales (Table 3). At T2, there were statistically significant scores across the different pain grades for all subscales of AQoL, except ‘‘physical senses’’, suggesting participants in grade I recorded better QoL (at T1, only the AQoL subscales for ‘‘independent living’’ and ‘‘total AQOL’’ were statistically significant). Additionally, at T1 there was a moderately positive correlation between pain intensity and AQoL domain for ‘‘individual living’’ (Spearman’s correlation coefficient (q) = 0.37, p = 0.003), ‘‘total’’ AQoL (q = 0.42, p = 0.001) and a weak positive correlation between pain intensity and AQoL ‘‘psychological well-being’’ (q = 0.25, p = 0.049), while at T2 correlation between pain intensity and AQoL ‘‘individual living’’ domain was no longer significant, and correlation between pain intensity and AQoL ‘‘psychological well-being’’ domain was moderate
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(q = 0.33, p = 0.004), suggesting more participants had deteriorated and became more dependent (data not shown).
Discussion This prospective longitudinal study showed that over a 7-year observational period, the pwMS in the community reported an increase in the prevalence of chronic pain by almost 15 % (from 65 % at baseline to 79 %), consistent with the prevalence reported in other studies [3–7, 9, 10, 21, 32, 33]. This occurred simultaneously with deterioration in disability, suggesting that with increasing disability and passage of time, the risk of pain syndromes also increased. Similar to other reports, the majority of pain reported was of mild-to-moderate intensity [9, 28, 32], episodic [9, 28], in more than one location (commonly in the limbs) [5, 9, 21], more nociceptive pain and of dysesthetic quality [4, 21, 32, 34]. MS-related pain is complex, multi-factorial, and has many dimensions [5]. The pain experience of the study sample affected many domains and aspects of life as outlined by the International Classification of Functioning, Disability, and Health (ICF) [35]. Surprisingly, few studies in literature report on the intensity of pain experienced by pwMS [13, 21]. In this study, participants reported a higher rate of pain intensity (severe to worst pain on VAS scale), which increased significantly over time. The overall pain intensity rating over time, however, was not significantly different. The findings of pain intensity are consistent with a previous study using similar standardized measures [9]. As expected, with progression of duration of disease, more participants reported higher disability, severely limiting their daily activities due to pain.
21 (34.4 %)
25 (41.4 %)
12 (35.3 %)
1 (14.3 %)
SP
PP
Total
Statistical analysis
38.0
29.4
35.7
34.18
37.2
Independent living
Social relationships
Physical senses
Psychological well-being
Total
17 (50.0 %)
26.4
30.2
26.4
31.6
22.6
28.9
4 (57.1 %)
23.7
21.3
25.9
25.5
29.7
30.8
2 (28.6 %)
5 (14.7 %)
6 (33.3 %)
6 (33.3 %)
3 (10.0 %)
4 (36.4 %)
13 (21.3 %)
0 (0 %)
7 (11.5 %)
34 (55.7 %)
18 (29.5 %)
18 (29.5 %)
30 (49.2 %)
11 (18.0 %)
61
33.6 33.8 32.4 37.2 29.9 30.2
v2 = 9.35, d = 2, p = 0.009 v2 = 1.14, d = 2, p = 0.57 v2 = 4.41, d = 2, p = 0.11 v2 = 4.65, d = 2, p = 0.0.04 v2 = 6.49, d = 2, p = 0.40
4 (40.0 %)
20 (44.4 %)
10 (52.6 %)
4 (22.2 %)
23 (54.8 %)
7 (50.0 %)
v2 = 0.11, d = 2, p = 0.95
v2 = 5.85, d = 4, p = 0.21
v2 = 5.87, d = 4, p = 0.21
34 (45.9 %)
32.5
38.5
33.3
33.4
29.7
32.6
5 (50.0 %)
14 (31.1 %)
5 (26.3 %)
6 (33.3 %)
13 (31.0 %)
5 (35.7 %)
24 (32.4 %)
II
61.5
47.4
52.3
55.3
60.6
38.6
0 (0 %)
2 (4.4 %)
2 (10.5 %)
2 (11.1 %)
1 (2.4 %)
1 (7.1 %)
4 (5.4 %)
III
60.0
53.6
42.0
54.3
55.8
1 (10.0 %)
9 (20.0 %)
2 (10.5 %)
6 (33.3 %)
5 (11.9 %)
1 (7.1 %)
12 (16.2 %)
IV
10 (13.5 %)
45 (60.8 %)
19 (25.7 %)
18 (24.3 %)
42 (56.8 %)
14 (18.9 %)
74
Total
v2 = 23.38, d = 3, p = 0.000
v2 = 12.21, d = 3, p = 0.007
v2 = 4.44, d = 3, p = 0.218
v2 = 13.27, d = 3, p = 0.004
v2 = 17.92, d = 3, p = 0.000
v2 = 13.77, d = 3, p = 0.003
v2 = 0.16, d = 6, p = 0.67
v2 = 0.25, d = 6, p = 0.16
v2 = 0.11, d = 6, p = 0.96
Statistical analysis
AQOL assessment of quality of life, GHQ general health questionnaire, PP primary progressive, RR relapsing remitting, SP secondary progressive, n total number
Grade 0 no pain, grade I low disability, low intensity; grade II low disability, high intensity; grade III high disability, moderately limiting; grade IV high disability, severely limiting. Kruskal–Wallis test*,
29.3
Illness
AQOL (mean rank)*
8 (44.4 %)
RR
4 (22.2 %)
6 (33.3 %)
6 (33.3 %)
Stage of disease
3 (6.5–8)
16 (53.3 %)
11 (36.7 %)
2 (3.5–6)
3 (27.3 %)
4 (36.4 %)
1 (0–3)
Expanded disability status scale (EDSS)
n (%)
IV
I
III
I
II
Chronic pain grade T2 (7-year follow-up) (n = 74), n (%)
Chronic pain grade T1 (baseline) (n = 61), n (%)
Table 3 Comparison of the participants across chronic pain grades
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Author's personal copy J Neurol Table 4 Pain-management techniques used by participants with chronic pain T1 (baseline) (n = 61) n (%)
T2 (7-year follow-up) (n = 74) n (%)
Medication Analgesics–nonopioids
33 (54.1)
13 (17.6)
Analgesics–opioids
4 (6.5)
4 (5.4)
Anti-inflammatory
11 (18.0)
7 (9.5)
Muscle relaxants and anticonvulsants
18 (29.5)
17 (23.0)
Antidepressants and anxiolytics
18 (29.5)
20 (27.0)
27 (44.3)
40 (54.1)
Manipulation Physical/electricala Change in temperature (hot/cold)
23 (37.7)
9 (12.2)
Support
9 (14.8)
13 (17.6)
Exercise
22 (36.1)
32 (43.2)
Rest or sleep
26 (42.6)
34 (45.9)
Psychosocial
7 (11.5)
1 (1.4)
Miscellaneousb
40 (65.6)
49 (66.2)
Alternativec
14 (23.0)
17 (23.0)
Distractiond
35 (57.4)
55 (74.3)
Other
a
Change in position, massage, change of clothes, comfortable furniture, pressure, whirlpool, transcutaneous electrical nerve stimulation (TENS), electric vibrator
b
Breathing, reduce stress, relaxation, pain clinic, biofeedback, talk to people, put others first, not dwell on pain, deal with it (pain), prayer, mediation
c
Acupuncture, chiropractor, vitamins, diet
d
Keep busy, read, handiwork, TV, computer, music. n total number
Despite the growing literature on the epidemiological aspects of acute and chronic pain in the MS population, little empirical research has focused specifically on the long-term effects of MS-related pain on patient functioning and emotional well-being. The findings in this study are consistent with findings from other reports [5, 21]. One study [21] (n = 49) reported an increase in MS-related pain from 53 to 86 % over a 5-year period, with deterioration in disability. Another study reported that QoL in pwMS-related chronic pain were lower compared to their counterparts without chronic pain [36]. Likewise, the participants in this study, classified in a lower CPG, reported a better QoL. There was, however, a significant worsening in the QoL scores over time (particularly on the AQoL domains of ‘‘independent living’’ and ‘‘physical senses’’), suggesting more participants deteriorated and became more dependent. Surprisingly, more participants were taking on physical activities as pain management techniques than medication usage. However, there was an increase in overall consultations with healthcare professionals (such as neurologists, rehabilitation physicians, pain specialists, surgeons, and allied health professionals) at T2. At follow-up (T2), the perceived barriers and difficulties that stopped the patients from accessing pain treatment seemed to ease. The most commonly reported
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barrier for pain management at both time points was lack of finances. Despite having problems with daily activities and having tried various modes of therapy, pwMS developed adaptation mechanisms or strategies to learn to cope with persistent pain. One study explored the cognitive-behavioral classifications of chronic pain in pwMS [18] (with cluster categories of ‘‘adaptive copers’’, ‘‘dysfunctional’’, and ‘‘interpersonally distressed’’) and reported higher level of activity interference and emotional distress due to pain; and lower perceived level of support impacts physical and psychological functioning. More research is needed to understand these cognitive-behavioral clusters in the MS population for targeted pain treatments. This study has several advantages, including standardized definition of chronic pain (over a longer time period), diagnosis of definite MS, a homogeneous MS population living in the community with quantified physical and cognitive deficits, who were mobile and able to participate, the face-to-face interview technique, number of variables studied relating to pain (intensity, frequency, location), and access and health service usage to allow comparison with previous studies. The sample in this study had diverse disability and included a range of disease course, duration, and severity of MS.
Author's personal copy J Neurol Table 5 Frequency of use of health services for pain by the participants
T1 (baseline) (n = 61) n (%)
T2 (7-year follow-up) (n = 74) n (%)
Practitioners consulted General practitioner
32 (52.5)
40 (54.1)
Neurologist
29 (47.5)
46 (62.2)
Rheumatologist
2 (3.3)
Rehabilitation physician
7 (11.5)
0 (0) 16 (21.6)
Pain specialist
2 (3.3)
8 (10.8)
Orthopedic surgeon
1 (1.6)
4 (5.4)
Allied health professionals Physiotherapist
21 (34.5)
36 (48.6)
Occupational therapist
4 (6.6)
7 (9.5)
Orthotist Podiatrist
1 (1.6) 2 (3.3)
1 (1.4) 4 (5.4)
Chiropractor
5 (8.2)
9 (12.2)
Acupuncturist
8 (13.1)
17 (23.0)
Hydrotherapist
1 (1.6)
0 (0)
Pharmacist
1 (1.6)
1 (1.4)
Masseur
4 (6.6)
11 (14.9)
Naturopath
2 (3.3)
4 (5.4)
Osteopath
4 (6.6)
8 (10.8)
Alternative practitioners
n total number Table 6 Perceived barriers to pain treatment reported by the participants
T1 (baseline) (n = 61) n (%)
T2 (7-year follow-up) (n = 74) n (%)
Lack of transportation
5 (8.2)
10 (13.5)
Lack of finances
12 (19.7)
11 (14.9)
Unable to see GP
0
1 (1.4)
Lack of accessible pain or MS specialists
8 (13.1)
2 (2.7)
Lack of ramp/lift/steps at doctor’s office
1 (1.6)
2 (2.7)
2 (3.3)
1 (1.4)
Side effects from medication
9 (14.8)
0
Fear of taking medication/dependence Worry that pain not perceived as real
10 (16.4) 3 (4.9)
0 0
Nothing works for pain so do not mention it
20 (32.8)
0
Environmental barriers
Cognitive and/or communication barriers Inability to explain pain due to memory or speech difficulty Other difficulties
GP general practitioner, n total number
The limitations of this study include a relatively small sample and potential sampling biases (e.g., reliance on convenience samples from clinical settings in a tertiary regional metropolitan region specializing in the treatment of MS), which may influence the generalizability of findings. The demographic and clinical characteristics of participants in this study, however, are similar to participants in other MS studies in terms of their age, gender, EDSS scores, and disease course [7, 8, 37, 38]. Participants who were institutionalized and bed-bound were not included,
which may have resulted in under-representation of disability related to severe pain, however, this was beyond the scope of this study. The pwMS often have concurrent depression, and assessment of depression itself was not studied as an outcome in this study. All assessments, however, were based on clinical judgment and information from medical records. Some participants failed to complete follow-up assessments and therefore were excluded from the analysis, which may also have introduced potential bias as these participants may be more vulnerable to pain. We
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Author's personal copy J Neurol Table 7 Quality of life in the participants measured using assessment of quality of life Items
T1 (baseline) (n = 61)
T2 (7-year follow-up) (n = 74)
Median
Median
IQR
Z scorea
p value
IQR
Illness (0–9)
6
5–6
5
4–6
-1.090
0.276
Independent living (0–9)
2
2–4
3
2–5
-4.242
0.000b
Social relationship (0–9)
2
1–3
2
1–3
-1.310
0.190
Physical senses (0–9)
0
0–1
0
0–1
-2.484
0.013b
3
2–4.5
4
2–5
-0.559
0.576
14
11–17
14
10.75–17.25
-2.193
0.028b
Psychological well-being (0–9) Total (0–45) a
Wilcoxon signed-rank test
b
Statistically significant at the 0.05 level (two-tailed)
IQR inter-quartile range, n total number
did not assess association of psychosocial variables such as coping strategies, pain-related, and other environmental factors, to reduce subject burden. The study was a crosssectional design without a control group, hence all findings are correlational in nature and causations for the associations observed cannot be established. Furthermore, findings in this study do not fully represent the impact of chronic pain on these persons as MS can affect several aspects of everyday life and function. Pain is common in pwMS and tends to increase over time, due to the MS process itself and from MS-related complications (trigeminal neuralgia, spasms) and musculoskeletal problems (posture, gait anomalies) [17, 18]. Truini et al. proposed mechanism-based classification for nine types of MS-related pain: trigeminal neuralgia and Lhermitte’s phenomenon (paroxysmal neuropathic pain due to ectopic impulse generation along primary afferents), ongoing extremity pain (deafferentation pain secondary to lesion in the spino-thalamocortical pathways), painful tonic spasms and spasticity pain (mixed pains secondary to lesions in the central motor pathways but mediated by muscle nociceptors), pain associated with optic neuritis (nerve trunk pain originating from nervi nervorum), musculoskeletal pains (nociceptive pain arising from postural abnormalities secondary to motor disorders), migraine (nociceptive pain favored by predisposing factors or secondary to midbrain lesions), and treatment-induced pains [39]. In clinical settings, however, pain can frequently be untreated or undertreated because of barriers related to recognition of the mechanism of pain, its assessment, and management, especially over time [5, 6, 39]. Understanding the impact of pain in pwMS in the longer term (beyond the acute phase) is important with improved patient survival and the shift of patient management to ambulatory care. This is a first study providing information on MS-related pain in the Australian community. A greater
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understanding of clinical manifestations of pain over longer-time, improved methods of assessment in this population may facilitate appropriate intervention and access to specialized chronic pain and disease management clinics to minimize pain-related disability in this group. Pain assessment may provide clinicians with additional information to guide in development of a tailored treatment program that best meets individual needs and should therefore be included routinely in comprehensive MS care. Physicians should be encouraged to assess and treat pain given its potential to cause sufficient interference with daily activities. More research is needed to inform clinical practice in understanding MS-related pain and associated psychological and psychosocial disability; and factors impacting chronic pain contributing to limitation in activity and participation. Pain-management programs as a component of multidisciplinary rehabilitation need further evaluation in well-designed clinical trials. Acknowledgments We thank all the participants in this study, Ms. L. Oscari for interviews, A/Prof. J. Pallant for statistical input, and Prof. T. Kilpatrick for access to the RMH MS Database. Conflicts of interest The authors have no conflicts of interest to report.
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