Deep muscle pain, tender points and recovery in acute whiplash patients: a 1-year follow-up study

Local sensitization to noxious stimuli has been previously described in acute whiplash injury and has been suggested to be a risk factor for chronic sequelae following acute whiplash injury. In this study, we prospectively examined the development of tender points and mechano-sensitivity in 157 acute whiplash injured patients, who fulfilled criteria for WAD grade 2 (n=153) or grade 3 (n=4) seen about 5 days after injury (4.8+/-2.3) and who subsequently had or had not recovered 1 year after a cervical sprain. Tender point scores and stimulus-response function for mechanical pressure were determined in injured and non-injured body regions at specific time-points after injury. Thirty-six of 157 WAD grade 2 patients (22.9%) had not recovered, defined as reduced work capacity after 1 year. Non-recovered patients had higher total tender point scores after 12 (p<0.05), 107 (p<0.05) and 384 days (p<0.05) relative to those who recovered. Tenderness was found in the neck region and in remote areas in non-recovered patients. The stimulus-response curves for recovered and non-recovered patients were similar after 12 days and 107 days after the injury, but non-recovered patients had steeper stimulus-response curves for the masseter (p<0.02) and trapezius muscles (p<0.04) after 384 days. This study shows early mechano-sensitization after an acute whiplash injury and the development of further sensitization in patients with long-term disability.     

Two different courses of impaired cervical kinaesthesia following a whiplash injury. A one-year prospective study

A longitudinal study was conducted to observe persons with neck pain after motor vehicle collisions. The aims were to reveal the prospective development of cervical kinaesthesia and to investigate the association between the test results and self-reported pain and disabilities. Two different cervical kinaesthetic tests, the Fly test and the Head-Neck Relocation test, measured movement control and the relocation accuracy of the cervical spine, respectively. Self-assessment measures included pain intensity (VAS), neck pain and disability (NDI), fear of re-injury (TAMPA) and psychological distress (GHQ-28). Seventy-four subjects entered the study, but 47 were eligible, as they participated in all 4 measurements at 1, 3, 6 and 12 months post-collision. According to the performances on the two kinaesthetic tests, the subjects could be classified into improvement and non-improvement groups, respectively. The result revealed, for the first time, two different courses of deficient cervical kinaesthesia. About half of the participants showed significant deteriorating performances in both kinaesthetic tests throughout the year (p < 0.002), while the other half improved their performances (p < 0.02). Generally, the relationships between the kinaesthetic tests and the self-assessment scores were not significant, irrespective of the performances on the two kinaesthetic tests. Accordingly, the results of the questionnaires correlated poorly or weakly with the kinaesthetic test results at all assessment points. The need for developing a new questionnaire, capturing the symptoms prevalent in patients with neck pain and cervical sensorimotor impairments is urgent. What determines the two different kinaesthetic courses need to be scrutinised in future research.     

In vitro opioid induced proliferation of peripheral blood immune cells correlates with in vivo cold pressor pain tolerance in humans: a biological marker of pain tolerance

There is substantial evidence for bidirectional communication between the immune system and the central nervous system, as the cells and signalling molecules of the immune system influence many central nervous system functions, for instance nociception. Opioids, such as morphine, produce analgesia and numerous other central and peripheral effects including sedation and euphoria, while their effects on the immune system are wide-ranging. There is considerable interindividual variability in basal nociception and response to opioids, however, the physiological and biological mechanisms underlying this are unclear. Therefore, we investigated the relationship between the immune system and basal nociceptive thresholds, using the proliferative response of isolated peripheral blood mononuclear cells and cold pressor pain tolerance. Here we show that the percent increase in proliferation of peripheral immune cells from 13 healthy subjects incubated with morphine ex vivo is highly correlated with the subjects' tolerance to noxious cold stimuli (Pearson r=0.92, P<0.0001). These pilot data provide evidence of a novel objective biological marker of pain tolerance in humans, which also links the immune and opioid systems with basal pain tolerance.     

Expectancy, fear and pain in the prediction of chronic pain and disability: a prospective analysis.

Studies with (sub) acute back pain patients show that negative expectancies predict pain and disability at a one-year follow up. Yet, it is not clear how expectations relate to other factors in the development of chronic disability such as pain and fear. This study investigates the relationship between expectations, pain-related fear and pain and studies how these variables are related to the development of chronic pain and disability. Subjects (N = 141) with back and/or neck pain (duration <1 year) were recruited via primary care. They completed measures on pain, expectancy, pain-related fear (pain-related negative affect and fear avoidance beliefs) and function. A one-year follow up was conducted with regard to pain and function. It was found that pain, expectancy, pain-related fear and function were strongly interrelated. In the cross-sectional analyses negative expectancies were best explained by frequent pain and a belief in an underlying and serious medical problem. Prospectively, negative expectancy, negative affect and a belief that activity may result in (re) injury or increased pain, explained unique variance in both pain and function at one-year follow up. In conclusion, expectancy, negative affect and fear avoidance beliefs are interrelated constructs that have predictive value for future pain and disability. Clinically, it can be helpful to inquire about beliefs, expectancy and distress as an indication of risk as well as to guide intervention. However, the strong interrelations between the variables call for precaution in treating them as if they were separate entities existing in reality.     

Persistent post-surgical pain and experimental pain sensitivity in the Tromsø study: Comorbid pain matters

In a large survey incorporating medical examination (N = 12,981), information on chronic pain and surgery was collected, and sensitivity to different pain modalities was tested. Tolerance to the cold pressor test was analysed with survival statistics for 10,486 individuals, perceived cold pressor pain intensity was calculated for 10,367 individuals, heat pain threshold was assessed for 4,054 individuals, and pressure pain sensitivity for 4,689 individuals. Persistent post-surgical pain, defined by self-report, was associated with lower cold pressor tolerance (sex-adjusted hazard ratio = 1.34, 95% confidence interval = 1.08–1.66), but not when adjusting for other chronic pain. Other experimental pain modalities did not differentiate between individuals with or without post-surgical pain. Of the individuals with chronic pain (N = 3352), 6.2% indicated surgery as a cause, although only 0.5% indicated surgery as the only cause. The associations found between persistent post-surgical pain and cold pressor tolerance is largely explained by the co-existence of chronic pain from other causes. We conclude that most cases of persistent post-surgical pain are coexistent with other chronic pain, and that, in an unselected post-surgical population, persistent post-surgical pain is not significantly associated with pain sensitivity when controlling for comorbid pain from other causes. A low prevalence of self-reported persistent pain from surgery attenuates statistically significant associations. We hypothesize that general chronic pain is associated with central changes in pain processing as expressed by reduced tolerance for the cold pressor test.     

Mechanisms of pain referral in patients with whiplash associated disorder

The aim was to investigate the mechanisms of pain referral in patients with whiplash associated disorder. Pain was induced in 12 controls and 12 patients with whiplash associated disorder by intramuscular electrical stimulation in the infraspinatus muscle and the ipsilateral upper arm, i.e., the area where all subjects perceived referred pain during conditioning stimulation in the infraspinatus muscle. Conditioning stimulation amounted to a pain intensity rated as 2/10 and 4/10. During conditioning stimulation in the infraspinatus muscle, sensitivity to test stimuli was assessed in the referred pain area (i.e., upper arm) and vice versa. Test stimuli consisted of intramuscular electrical stimulation corresponding to innocuous perception threshold, electrical pain threshold, and pain intensities rated as 2/10, 4/10 and 6/10, respectively. Compared to controls, patients with whiplash associated disorder had increased pain sensitivity (p≤0.01) and indicated larger areas of referred pain ((p≤0.003) during stimulation at the infraspinatus muscle; p≤0.03 during stimulation at the upper arm), including proximal referral of pain which was never reported by controls (p≤0.05). During conditioning stimulation in the infraspinatus muscle (4/10) all subjects reported referred pain in the upper arm (corresponding to the test site) and innocuous perception thresholds (p<0.05)(patients) and electrical pain thresholds (p<0.001) (controls) decreased. Conditioning stimulation in the upper arm did not affect sensitivity to test stimuli in the infraspinatus muscle. In conclusion, patients with whiplash associated disorder had increased sensitivity to painful stimulation, reported larger areas of referred pain during the same subjectively painful conditioning stimulation (i.e., lower absolute stimulus intensities), including proximal pain referral which was never seen in controls, indicating aberrant processing of nociceptive input. The perceptual integration of nociceptive stimuli during simultaneous stimulation did not differ between groups suggesting that divergence of nociceptive input from the focal pain area leading to excitation of neurones with projected fields in the referred pain area most likely explains referred pain in both groups alike.     

Fear of pain, not pain catastrophizing, predicts acute pain intensity, but neither factor predicts tolerance or blood pressure reactivity: an experimental investigation in pain-free individuals.

Previous studies of the Fear-Avoidance Model of Exaggerated Pain Perception have commonly included patients with chronic low back pain, making it difficult to determine which psychological factors led to the development of an "exaggerated pain perception". This study investigated the validity of the Fear-Avoidance Model of Exaggerated Pain Perception by considering the influence of fear of pain and pain catastrophizing on acute pain perception, after considering sex and anxiety. Thirty-two males and 34 females completed the State-Trait Anxiety Inventory, the Fear of Pain Questionnaire, and the Coping Strategies Questionnaire. Subjects underwent a cold pressor procedure and tolerance, pain intensity, and blood pressure reactivity were measured. Sex, anxiety, fear of pain, and pain catastrophizing were simultaneously entered into separate multiple regression models to predict different components of pain perception. Tolerance was not predicted by fear of pain, pain catastrophizing, or anxiety. Pain intensity at threshold and tolerance were significantly predicted by fear of pain, only. Blood pressure reactivity to pain was significantly predicted by anxiety, only. These results suggest that fear of pain may have a stronger influence on acute pain intensity when compared to pain catastrophizing, while neither of the factors predicted tolerance or blood pressure reactivity.     

The influence of fear of movement and pain catastrophizing on daily pain and disability in individuals with acute whiplash injury: a daily diary study

Previous research supports the fear-avoidance model in explaining the transition from acute to chronic non-specific musculoskeletal pain. However, there is still little knowledge on when this vicious circle of pain, disability, pain catastrophizing and fear of movement starts. We performed a daily diary study in 42 patients with acute whiplash injury. Pain, disability, pain catastrophizing and fear of movement were measured on a daily basis with paper diaries for 21 consecutive days. Most participants showed a decline in pain and disability from day 1 to day 21 and this was paralleled by a decline in the fear of movement and pain catastrophizing. Multilevel analyses showed that both between and within persons, high levels of pain catastrophizing and fear of movement are associated with more pain and disability. Moreover, the fear of movement was also predictive of pain and disability on the following day. We also examined the reverse association, that is, whether the changes in pain predict changes in the next day's fear of movement and pain catastrophizing. Although for the fear of movement the model reached significance, the amount of explained variance was negligible. In conclusion, this study provides evidence that already in the early stages of whiplash-related complaints, significant associations between fear of movement and pain intensity and disability occur, and that this association may be predictive of the persistence of pain.     

Post-trauma ratings of pre-collision pain and psychological distress predict poor outcome following acute whiplash trauma: a 12-month follow-up study

Patients with acute whiplash trauma were followed to examine if post-trauma ratings of pre-collision pain and psychological distress were associated with reduced work capability and neck pain at 12 months follow-up. The study included 740 consecutive patients (474 females, 266 males) referred from emergency departments or primary care after car accidents in four counties in Denmark. After the collision patients received a questionnaire on psychological distress, unspecified pain and socio-demographics and 12 months later a follow-up on work capability and neck pain was performed. Risk factors were identified by multiple logistic regression analysis. Factors associated with affected work capacity at the 12-month follow-up were pre-collision unspecified pain condition (OR=2.4, p=0.002) and socio-demographic characteristics: female gender, low educational level, unemployment and blue collar worker. Factors associated with considerable neck pain at follow-up were pre-collision unspecified pain (OR=3.5, p<0.000), pre-collision high psychological distress (OR=2.1, p=0.03) and socio-demographic characteristics: female gender and formal education >4 years. Pre-collision neck pain and severity of accident were not associated with poor outcome. In conclusion unspecified as opposed to specified pain (neck pain) before the collision is associated with poor recovery and high accumulation of pre-collision psychological distress is associated with considerable neck pain at follow-up. However, no conclusions on causality can be drawn. Personal characteristics before the collision are important for recovery and attention to pre-collision characteristics may contribute to the prevention of poor recovery after acute whiplash trauma.     

Demographic and medical parameters in the development of complex regional pain syndrome type 1 (CRPS1): prospective study on 596 patients with a fracture

Limited data are available on the incidence of complex regional pain syndrome type 1 (CRPS1) and on demographic and medical risk factors for the development of CRPS1. The objective of this study was to investigate the incidence of CRPS1 in patients with a fracture using 3 sets of diagnostic criteria and to evaluate the association between demographic/medical factors and the development of CRPS1 diagnosed with the Harden and Bruehl criteria. A prospective multicenter cohort study of 596 patients (ages 18 years and older) with a single fracture of the wrist, scaphoid, ankle, or metatarsal V, recruited patients from the emergency rooms of 3 Dutch hospitals. Of the 596 participants, 42 (7.0%) were diagnosed with CRPS1 according to the Harden and Bruehl criteria, 289 (48.5%) according to the International Association for the Study of Pain criteria, and 127 (21.3%) according to the criteria of Veldman. An analysis of the medical and demographic differences revealed that patients in whom CRPS1 later developed more often had intra-articular fractures, fracture dislocations, rheumatoid arthritis, or musculoskeletal comorbidities. An ankle fracture, dislocation, and an intra-articular fracture contributed significantly to the prediction of the development of CRPS1. No CRPS1 patients were symptom free at 12 months (T3). At baseline, patients with CRPS1 had significantly more pain than patients without CRPS1 (P<.001). The incidence of the diagnosis of CRPS1 after a single fracture depends to a large extent on the diagnostic criteria used. After a fracture, 7% of the patients developed CRPS1 and none of the patients were free of symptoms at 1-year follow-up.     

Acute stress response and recovery after whiplash injuries. A one‐year prospective study

Chronic whiplash‐associated disorder (WAD) represents a major medical and psycho‐social problem. The typical symptomatology presented in WAD is to some extent similar to symptoms of post traumatic stress disorder. In this study we examined if the acute stress reaction following a whiplash injury predicted long‐term sequelae. Participants with acute whiplash‐associated symptoms after a motor vehicle accident were recruited from emergency units and general practitioners. The predictor variable was the sum score of the impact of event scale (IES) completed within 10 days after the accident. The main outcome‐measures were neck pain and headache, neck disability, general health, and working ability one year after the accident. A total of 737 participants were included and completed the IES, and 668 (91%) participated in the 1‐year follow‐up. A baseline IES‐score denoting a moderate to severe stress response was obtained by 13% of the participants. This was associated with increased risk of considerable persistent pain (OR=3.3; 1.8–5.9), neck disability (OR=3.2; 1.7–6.0), reduced working ability (OR=2.8; 1.6–4.9), and lowered self‐reported general health one year after the accident. These associations were modified by baseline neck pain intensity. It was not possible to distinguish between participants who recovered and those who did not by means of the IES (AUC=0.6). In conclusion, the association between the acute stress reaction and persistent WAD suggests that post traumatic stress reaction may be important to consider in the early management of whiplash injury. However, the emotional response did not predict chronicity in individuals.     

Pain thresholds and tenderness in neck and head following acute whiplash injury: a prospective study

OBJECTIVE OF THE INVESTIGATION: In a 6-month prospective study of 141 consecutive acute whiplash-injured participants, and 40 acute, ankle-injured controls, pain and tenderness in the neck/head, and at a distant control site, were measured. BASIC PROCEDURES: Muscle palpation and pressure algometry in five head/neck muscle-pairs were performed after 1 week and 1, 3 and 6 months after injury. Algometry was performed at a distant control site. MAIN FINDINGS: Whiplash-injured patients had lowered pressure-pain-detection thresholds and higher palpation-score initially in the neck/head, but the groups were similar after 6 months, and the control site was not sensitized. PRINCIPAL CONCLUSION: Focal, but not generalized, sensitization to musculoskeletal structure is present until 3 months, but not 6 months, after whiplash injury, and probably does not play a major role in the development of late whiplash syndrome. Pressure algometry and palpation are useful clinical tools in the evaluation of neck and jaw pain in acute whiplash injury.     

Musculoskeletal pain associated with recreational yoga participation: A prospective cohort study with 1-year follow-up

Background

Yoga is a popular complementary therapy for musculoskeletal pain. There are few studies however, that have examined the risks of recreational participation for causing musculoskeletal pain.

Increased cerebral blood flow velocity induced by cold pressor test in migraine: a possible basis for pathogenesis?

Noradrenergic nuclei of the locus coeruleus are believed to be involved in migraine pathogenesis. We recently demonstrated a typical intracerebral vasoconstriction after prolonged (5 min) exposure to cold pressor test (CPT), likely related to a central noradrenergic mechanism modulated at the locus coeruleus level and eliminated by pretreatment with clonidine. In the present study, we used transcranial Doppler ultrasonography to monitor blood flow velocity (BFV) changes to CPT in the middle cerebral artery (MCA) of migraine with (MA, n =12) and without (MO, n =15) aura subjects. CPT induced a significant increase in BFV and a concomitant decrease in the pulsatility index (PI), a pattern which is the opposite of the results obtained with controls. The results were comparable when controls were pretreated with clonidine. The MO patients produced an intermediate pattern between the MA and control subjects. A possible altered modulatory effect of opioids and/or serotonin on noradrenergic nuclei of the brainstem is the possible cause of the observed inverse response in migraine, suggesting intracerebral vasomotor instability in these patients.     

Effects of mood on pain responses and pain tolerance: an experimental study in chronic back pain patients

Although chronic pain and depression commonly co-occur, causal relationships have yet to be established. A reciprocal relationship, with depression increasing pain and vice versa, is most frequently suggested, but experimental evidence is needed to validate such a view. The most straightforward approach would be a demonstration that increasing or decreasing depressed mood predictably modifies pain responses. The current experiment tested whether experimentally induced depressed and happy mood have differential effects on pain ratings and tolerance in 55 patients suffering from chronic back pain. Participants were randomly assigned to depressed, neutral (control) or elated mood induction conditions. They completed a physically passive baseline task prior to receiving mood induction, then a clinically relevant physically active task (holding a heavy bag) to elicit pain responses and tolerance. Measures were taken immediately after the baseline task and immediately after the mood induction to assess the changes in mood, pain ratings and tolerance before and after the experimental manipulation. Results indicate that the induction of depressed mood resulted in significantly higher pain ratings at rest and lower pain tolerance, whilst induced happy mood resulted in significantly lower pain ratings at rest and greater pain tolerance. Correlations between changes in mood on the one hand and changes in pain response and pain tolerance on the other hand were consistent with these findings. It is concluded that, in chronic back pain patients, experimentally induced negative mood increases self-reported pain and decreases tolerance for a pain-relevant task, with positive mood having the opposite effect.     

Tonic pain: a SPET study in normal subjects and cluster headache patients

Whether the pathogenesis of cluster headache (CH) is peripheral or central is still matter of debate. An involvement of central structures related to pain perception and modulation, which also causes an alteration of the physiological pattern of pain perception in CH, has been hypothesized. We investigated the pattern of brain response to pain in normal subjects and CH patients by evaluating the cerebral blood flow (CBF) changes using an experimental model of tonic aching pain stimulation, the cold water pressor test (CWPT). CBF was assessed quantitatively by the Xe-133 inhalation method and single photon emission tomography (SPET), at rest and during CWPT, as previously described (Di Piero et al., 1994). CWPT was performed in 12 volunteers and in seven patients with CH. All the CH patients had a left-sided headache and were studied in a headache-free phase out of the cluster period. During CWPT, volunteers showed a significant CBF increase in the contralateral primary sensorimotor (P<0.001), frontal (P<0.01) and temporal (P<0.002) regions and thalamus (P<0.01) and in the ipsilateral temporal (P<0.005) and anterior cingulate (P<0.01) regions. During left-hand stimulation (ipsilateral to the headache side) by CWPT in CH patients, CBF changes were significantly lower than those observed in volunteers in the contralateral primary sensorimotor region (P<0.0005) and thalamus region (P<0.01). There were no significant differences in the brain response observed during the stimulation of the hand contralateral to the headache side. In conclusion, in a headache-free phase out of the cluster period, the pattern of cerebral activation during tonic pain stimulation of the hand ipsilateral to the headache side is critically modified in CH patients in areas which are probably involved in the detection of the stimulus intensity. This modification may reflect a marker of a biological modification of the pain conveyance system. The fact that it is also present out of the active period of the disease, suggests a possible involvement of central tonic pain mechanisms in the pathogenesis of CH.     

Does the number of musculoskeletal pain sites predict work disability? A 14-year prospective study

Various risk factors associated with disability pensioning have been reported. This study investigated the relationship between the number of pain sites and risk of receiving a disability pension. We hypothesised that risk of work disability would increase as the number of pain sites increased, even after controlling for potential confounders. In 1990 and 2004, questionnaire on musculoskeletal pain was sent via post to six age groups in Ullensaker, Norway. Data on demographic, health and work‐related variables were also collected. After excluding individuals due to reach retirement age in 2004, we followed 1354 (66%) persons who were classified in 1990 as “employed”, “unemployed”, “homemaker”, or “student”. Among them, 176 persons had received long‐term or permanent work disability pension in 2004. Bivariate analyses showed that the prevalence of disability pensions was strongly associated with the number of pain sites. Controlling for gender and age almost unaltered the relationship. However, a model controlling for all significant confounders showed that general health and sick leave previous year captured almost all the predictive power of the number of pain sites on work disability. Since these variables could be seen as intermediate variables and not confounders, they were excluded in a new model which gave a strong “dose–response” relationship between number of pain sites and disability with a 10‐fold increase from 0 to 9–10 pain sites. The predictive validity of the number of pain sites in determining future disability renders this simple measurement useful for future research on musculoskeletal pain and functioning.     

Investigating the effects of anxiety sensitivity and coping on the perception of cold pressor pain in healthy women.

Research indicates that anxiety sensitivity may be related to the negative experience of pain, especially amongst women. Further evidence with chronic pain patients indicates that anxiety sensitivity may result in avoidance pain-coping strategies. However, this effect has not yet been experimentally investigated in healthy groups. Therefore, the current study sought to investigate the effect of anxiety sensitivity and coping on women's responses to pain. Thirty women who were classified as high in anxiety sensitivity and 30 women classified as low in anxiety sensitivity participated. Within each anxiety sensitivity group, half the participants (n = 15) were randomly instructed to either focus on or avoid cold pressor pain sensations. As expected, women high in anxiety sensitivity were found to report higher levels of sensory and affective pain. Also, and consistent with previous research into anxiety sensitivity, no differences were found between anxiety sensitivity groups for measures of pain threshold or pain tolerance. The pain coping instruction manipulation was found to moderate pain experience, in that the avoidance strategy resulted in higher pain ratings compared to when instructed to focus. Finally, high anxiety sensitive women reported greater pain when instructed to avoid rather than focus on cold pressor pain. These results are discussed in light of previous research and future directions for pain management.     

Quantitative sensory testing and pain tolerance in patients with mild to moderate Alzheimer disease compared to healthy control subjects

Patients with Alzheimer disease (AD) report pain less frequently than their cognitively intact peers. It has been hypothesized that pain processing is altered in AD. The aim of this study was to investigate agreement and reliability of 3 pain sensitivity tests and to examine pain threshold and tolerance in patients with AD. We examined 29 patients with mild to moderate AD and 29 age- and gender-matched healthy control subjects with quantitative sensory testing, ie, assessments of detection threshold (warmth detection threshold [WDT]) and pain threshold (heat pain threshold [HPT], pressure algometry, cold pressor test), and assessments of tolerance (pressure algometry, cold pressor test). All procedures were done twice on day 1, 1 hour apart, and repeated on day 2. We found no difference between groups for WDT (patient vs control subjects: mean [95% confidence interval]: 35.5°C [33.4°C to 37.6°C] vs 35.4°C [34.3°C to 36.5°C], P = .8) or HPT (41.2°C [40.0°C to 42.4°C] vs 42.3°C [41.1°C to 43.5°C], P = .24). We observed comparable thresholds for pressure algometry (median [25% to 75% interquartile range]: 120 kPa [100 to 142 kPa] vs 131 kPa [113 to 192 kPa], P = .10), but significantly lower tolerance in AD patients (213 kPa [188 to 306 kPa] vs 289 kPa [262 to 360 kPa], P = .008). No differences were found for the cold pressor test. The study demonstrated good replicability of the sensory testing data with comparable data variability, for both groups, which supports the use of these methods in studies of patients with mild to moderate AD. Contrary to previous studies, we observed a reduced pain tolerance in patients with mild to moderate AD, which suggests that the reduced report of pain cannot be explained by reduced processing of painful stimuli.     

Postoperative patients’ perspectives on rating pain: A qualitative study

BackgroundIn postoperative pain treatment patients are asked to rate their pain experience on a single uni-dimensional pain scale. Such pain scores are also used as indicator to assess the quality of pain treatment. However, patients may differ in how they interpret the Numeric Rating Scale (NRS) score.ObjectivesThis study examines how patients assign a number to their currently experienced postoperative pain and which considerations influence this process.MethodsA qualitative approach according to grounded theory was used. Twenty-seven patients were interviewed one day after surgery.ResultsThree main themes emerged that influenced the Numeric Rating Scale scores (0–10) that patients actually reported to professionals: score-related factors, intrapersonal factors, and the anticipated consequences of a given pain score. Anticipated consequences were analgesic administration—which could be desired or undesired—and possible judgements by professionals. We also propose a conceptual model for the relationship between factors that influence the pain rating process. Based on patients’ score-related and intrapersonal factors, a preliminary pain score was “internally” set. Before reporting the pain score to the healthcare professional, patients considered the anticipated consequences (i.e., expected judgements by professionals and anticipation of analgesic administration) of current Numeric Rating Scale scores.ConclusionsThis study provides insight into the process of how patients translate their current postoperative pain into a numeric rating score. The proposed model may help professionals to understand the factors that influence a given Numeric Rating Scale score and suggest the most appropriate questions for clarification. In this way, patients and professionals may arrive at a shared understanding of the pain score, resulting in a tailored decision regarding the most appropriate treatment of current postoperative pain, particularly the dosing and timing of opioid administration.