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Pain catastrophizing is associated with increased physical disability in patients with anterior knee pain
, Michael Zacchillib, Kirk A. Campbella, Michael Alaiaa, Laith Jazrawia, Eric Straussa
∗Corresponding author: Kamali Thompson. Kamali.thompson@nyulagone.edu
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Received: ,
Accepted: ,
This article was originally published by Reed Elsevier India Pvt. Ltd. and was migrated to Scientific Scholar after the change of Publisher.
Abstract
Abstract
The traditional nociceptive approach to pain identifies the mind and body as functionally separate. However, the biopsychosocial model accounts for the impact of social, psychological and physical factors on the patient experience. The purpose of this study was to determine the relationship between diagnosis, physical disability, and psychological distress among patients with anterior knee pain-one of the most common complaints in an orthopedic clinic.
This was a single-center, cross-sectional study. Patients presenting for initial evaluation of knee pain completed the Pain Catastrophizing Scale, Kujala Anterior Knee Pain Scale, and SF-12 questionnaires. Statistical analysis was performed using SPSS Version 24.
207 patients, 108 (52.2%) females and 99 (47.8%) males, with a mean age 44.5 ± 15.4 years were enrolled. The osteoarthritis cohort had the highest pain catastrophizing score (17 ± 14.5), lowest Kujala score (48.3 ± 18.1), lowest SF-12 PCS (37.5 ± 8.3), and lowest SF-12 MCS (50.8 ± 11.0). Across all diagnoses, there was a statistically significant negative correlation between the total Pain Catastrophizing Score (PCS) and the Kujala, SF-12 Physical, and SF-12 Mental Component Scores. Bivariate and multivariate analysis demonstrated a correlation between PCS and duration of symptoms and African-Americans. The Kujala and SF-12 PCS demonstrated a statistically significant correlation with age, smoking, and the Asian Indian ethnicity. The SF-12 MCS showed a significant relationship with the Asian Indian ethnicity. Bivariate analysis also showed a statistically significant relationship between the SF-12 PCS and the SF-12 MCS.
Knee pain patients presenting to an orthopedic sports medicine clinic demonstrate diminished physical quality of life and psychological reserves. This study determined an association between catastrophizing behavior and other patient reported outcomes measuring pain, physical distress, quality of life and mental/emotional well-being. To optimize patient outcomes, psychological domain should be managed contemporaneously to orthopedic pathology.
Keywords
Patellofemoral pain syndrome
Osteoarthritis
Pain catastrophizing scale
Psychosocial factors
1 Introduction
Knee pain is one of the most common complaints seen in healthcare clinics.1 The intensity of symptoms and disability experiences by patients are influenced by multiple factors, including both physical and psychological factors.2 In fact, there is some evidence that suggests a patient's psychological state may have a greater impact on their pain and disability than the physical pathology itself.3,4 For example, providers might attribute patients' complaints and disability exclusively to physical pathology, when present, while disregarding psychological factors entirely unless there is no other recourse.
Due to these prejudices, inclusion of the psychological domain in orthopedic outcomes research is infrequent and has generally been limited to select populations—such as anterior cruciate ligament reconstruction or total joint arthroplasty patients.5 The impact of psychological factors on the physical quality of life in the “knee pain” patient at the time of presentation to an orthopedic surgeon remains poorly described.
The biopsychosocial model, first introduced by Keefe et al.6 in 1999, is a multidimensional approach to the characterization of pain. While the traditional nociceptive approach to pain identifies the mind and body as functionally separate, the biopsychosocial model accounts for the impact of social, psychological and physical factors on the patient experience.7 This study served to evaluate the influence of physical and psychological factors on patient's perception of their physical disability from anterior knee pain. Our hypothesis was that health-related physical quality of life in patients reporting knee pain would be influenced by psychological distress and catastrophizing behavior.
2 Methods
2.1 Study design
This was an institutional review board approved single-center, prospective, cross-sectional study performed between January 2016 and August 2016. Inclusion criteria were: chief complaint of knee pain, presentation for initial evaluation to a fellowship-trained orthopedic sports medicine surgeon, the presence of a magnetic resonance imaging (MRI) at presentation, and plain radiographs obtained prior to or upon initial evaluation. Exclusion criteria were: age less than 18, prior evaluation by an orthopedic surgeon, and the absence of plain radiographs or MRI.
Consenting patients were asked to complete a survey with the following questionnaires: Pain Catastrophizing Scale (PCS), Kujala Anterior Knee Pain Scale, and Short Form-12 (SF-12) Physical and Mental Components. Demographic data, including age, gender, self-reported ethnicity, smoking status, and marital status, were obtained through patient surveys and chart review. Patient charts were also reviewed to record height, weight, diagnosis (as determined by the treating surgeon and confirmed with radiographic imaging), and history of mental health illness.
Patients were categorized based on orthopedic pathology (according to surgeon diagnosis and confirmed with radiographic imaging): ACL injury, bursitis, effusion, gout, herniated nucleus pulposus, IT band syndrome, LCL/MCL injury, meniscus injury, osteochondral injury, osteoarthritis, patellofemoral pain syndrome, and stress fracture.
2.2 Instruments
The Pain Catastrophizing Scale (PCS) is a 13-item scale, with each item rated on a 5-point scale: 0 (Not at all) to 4 (all the time). A higher score represents more catastrophizing thoughts. The PCS is broken down into three subscales: magnification, rumination, and helplessness. The use of this instrument will help determine the thoughts and feelings experienced by the patient resulting from their diagnosis. Current literature has shown reliability and validity in the adult population as well as in outpatient samples.8,9
The Kujala Anterior Knee Pain Scale is a 13-item scale designed to assess pain, with each item rated on a 0–5 or 0–10 scale: 0 (constant complaint or difficulty) to 5 or 10 (no complaint or difficulty). A score closer to 0 represents more pain and difficulty functioning, while a score closer to 100 represents a patient in a better state of health.10 The Kujala AKPS has shown to be reliable in terms of internal consistency, equivalence across short and long forms, validity, and standard error of measurement.11
The Short Form Health Survey (SF-12) is a well-known and validated 12-item survey that assesses health-related quality of life within a 4-week recall period.12,13 It is a shorter and more effective alternative to the SF-36. The physical component score encompasses quality of life as it relates to the physical domain. The mental component scores represents the patient's mental and emotional well-being. Similar to the Kujala, higher scores represent a better state of health and quality of life.
2.3 Statistical analysis
Statistical analysis was completed using SPSS Version 24 (IBM, Armonk NY). A bivariate analysis was used to determine significant correlations among continuous variables including age, BMI (body mass index), PCS, Kujala and SF-12 physical and mental component scores. A one-way analysis of variance (ANOVA) and t-tests were performed for significant differences between groups for categorical variables including sex, diagnosis, ethnicity, smoking status, and marital status. Findings were considered significant at p < 0.05, two sided. Results reaching statistical significance were selected and multivariate analysis was performed. Continuous variables are presented as mean, standard deviation, and range. Categorical variables are presented as frequency and percentage.
3 Results
3.1 Patient demographics
A total of 207 patients were enrolled from January 2016 to August 2016. A summary of patient characteristics can be seen in Table 1. The mean age (±standard deviation) was 44.5 ± 15.4 years. The mean BMI of the patients was 27.1 ± 5.9. The mean duration of symptoms was 8.71 ± 15.04 months. The highest frequencies of patients were female (52.2%), Caucasian American (73.9%), and non-smokers (68.6%).
| Agea (years) | 44.5 ± 15.4 (18–78) |
| Sexb | |
| Male | 99 (47.8%) |
| Female | 108 (52.2%) |
| BMIa (kg/m2) | 28.1 ± 5.9 |
| Race | |
| Caucasian American | 153 (73.9%) |
| African American | 20 (9.7%) |
| Spanish/Hispanic | 16 (7.7%) |
| Asian American | 4 (1.9%) |
| Asian Indian | 3 (1.4%) |
| Non-disclosed | 2 (1.0%) |
| Marital Statusb | |
| Married/Partner | 101 (48.8%) |
| Single | 89 (43.0%) |
| Divorced | 10 (4.8%) |
| Widowed | 2 (1.0%) |
| Non-disclosed | 5 (2.4%) |
| Smoking Statusb | |
| Non-smoker | 142 (68.6%) |
| Former smoker | 46 (22.2%) |
| Current smoker | 18 (8.7%) |
| Non-disclosed | 1 (0.5%) |
Thirty-six (17.4%) patients either disclosed or had a documented history of mental illness (Table 2), which included depression (8.7%), anxiety (7.2%), sleep disorder (3.4%), and attention deficient (1.9%). Twenty-seven patients (13.0%) admitted to a single disorder, eight patients (3.9%) admitted to two disorders, and one patient admitted to three (0.5%). Bivariate analysis demonstrated there was no relationship of between mental illness and patient reported outcomes.
| Knee Pathology | Patient (n = 36) |
| ACL | 4 (11.1%) |
| LCL | 1 (2.8%) |
| Meniscus | 11 (30.6%) |
| Osteochondral injury | 1 (2.8%) |
| Osteoarthritis | 13 (36.1%) |
| Patellar fracture | 1 (2.8%) |
| PFPS | 5 (13.9%) |
| Number of diagnosed mental illnesses | |
| Three diagnosis | 1 (2.8%) |
| Two diagnosis | 8 (22.2%) |
| One diagnosis | 27 (75%) |
| Psychiatric Diagnosis | |
| Anxiety | 15 (41.7%) |
| Attention deficient | 4 (11.1%) |
| Depression | 18 (50%) |
| Sleep | 7 (19.4%) |
Patients were separated according to diagnosis ( Table 3). The most common diagnoses were meniscal injury (n = 66), osteoarthritis (n = 50), patellofemoral pain syndrome diagnosis (n = 41), ACL injury (n = 18), and osteochondral injury (n = 14). The diagnosis with the highest Pain Catastrophizing Score was osteoarthritis (17 ± 14.5). The diagnoses with the lowest Kujala score, or most pain, was the other category, less common diagnoses (41.7 ± 10.0), followed by osteoarthritis (48.3 ± 18.1). The diagnoses with the lowest SF-12, or highest physical disability, was the osteoarthritis cohort (37.5 ± 8.3). While SF-12 MCS scores were similar between cohorts, the diagnosis with the lowest SF-12 MCS score was osteoarthritis (50.8 ± 11.0).
| Diagnosis | Patients (n = 207) | Total PCS | Kujala | SF-12 PCS | SF-12 MCS |
| ACL | 18 (8.7%) | 12.6 ± 10.8 | 56 ± 24.9 | 43.6 ± 9.1 | 51.7 ± 7.8 |
| ACL tear/sprain | 14 (6.7%) | ||||
| ACL multi | 4 (1.9%) | ||||
| Meniscus | 66 (31.9%) | 13.5 ± 13.3 | 59.8 ± 16.7 | 39.6 ± 9.6 | 51.6 ± 11.0 |
| Lateral | 11 (5.3%) | ||||
| Medial | 55 (26.6%) | ||||
| Osteochondral injury | 14 (6.7%) | 14.3 ± 9.9 | 65.7 ± 21.7 | 41.7 ± 8.2 | 53.1 ± 6.9 |
| Osteoarthritis | 49 (23.7%) | 17 ± 14.5 | 48.3 ± 18.1 | 37.5 ± 8.3 | 50.8 ± 11.0 |
| Patellofemoral pain syndrome | 41 (19.8%) | 10.8 ± 9.6 | 70.7 ± 18.2 | 44 ± 8.6 | 52.1 ± 7.9 |
| PFPS | 29 (14.0%) | ||||
| Patellar instability | 8 (3.9%) | ||||
| Patellar tendinitis | 4 (1.9%) | ||||
| Other | 19 (1.0%) | 3.5 ± 2.7 | 41.7 ± 10.0 | 54.8 ± 6.8 | 54.8 ± 6.8 |
| Bursitis | 4 (1.9%) | ||||
| Effusion | 2 (1.0%) | ||||
| Gout | 1 (0.5%) | ||||
| HNP | 1 (0.5%) | ||||
| IT band syndrome | 2 (1.0%) | ||||
| LCL/MCL | 7 (3.4%) | ||||
| Stress fracture | 2 (1.0%) |
3.2 Patient reported outcomes
Across all diagnoses, there was a statistically significant negative correlation between the total Pain Catastrophizing Score (PCS) and the Kujala, SF-12 Physical Component Scores, and SF-12 Mental Component Scores (Table 4). Bivariate and multivariate analysis demonstrated a correlation between PCS and the following demographics: duration of symptoms (r = 0.14, p = 0.05) and African-Americans (estimate = 5.42, p = 0.030).
| Total PCS | Kujala | SF-12 PCS | SF-12 MCS | |||||
| Coefficient | p-Value | Coefficient | p-Value | Coefficient | p-Value | Coefficient | p-Value | |
| Agea | 0.03 | 0.63 | −0.27 | <0.001 | −0.16 | 0.018 | 0.07 | 0.37 |
| BMIa | 0.09 | 0.05 | −0.27 | <0.001 | −0.34 | <0.001 | −0.07 | 0.30 |
| Duration of symptomsa | 0.14 | 0.05 | 0.032 | 0.663 | −0.03 | 0.69 | −0.02 | 0.83 |
| Smokingb | 0.22 | 0.42 | 6.39 | 0.002 | 10.50 | 0.007 | 0.19 | 0.82 |
| Ethnicityb | 5.33 | <0.001 | 3.56 | 0.008 | 2.19 | <0.001 | 4.37 | 0.002 |
| African Americansc | 5.42 | 0.03 | 2.99 | 0.44 | −2.05 | 0.26 | −2.51 | 0.29 |
| Asian Indiañ | 7.50 | 0.10 | −22.37 | 0.001 | 6.43 | 0.05 | 7.44 | 0.05 |
The Kujala demonstrated a significant correlation between age (r = −0.27, p = <0.001), BMI (r = −0.27, p = <0.001), smoking (F = 6.39, p = <0.002), and the Asian Indian ethnicity (F = −22.4, p = 0.001). The SF-12 PCS also demonstrated statistically significant relationships between age (r = −0.16, p = 0.018), BMI (r = −0.34, p = <0.001), smoking (F = 10.5, p = 0.007) and the Asian Indian ethnicity (estimate = 6.4, p = 0.05). The SF-12 MCS showed a statistically significant relationship with the Asian Indian ethnicity (F = 7.44, p = 0.05). Bivarate analysis also showed statistically significant relationship between the SF-12 PCS and the SF-12 MCS.
4 Discussion
The goal of every physician is to provide excellent patient care. Because the intensity of symptoms and disability experienced are influenced by multiple factors, all biopsychosocial aspects must be addressed to effectively treat patients' pain.2 Our study determined biological (age, BMI, duration of symptoms), psychological (pain catastrophizing score) and social factors (ethnicity) all affected the intensity of patients’ pain.
We hypothesized the health-related physical quality of life in patients reporting knee pain would be influenced by psychological distress and catastrophizing behavior. The results of the study supported our hypothesis, as there was an association between catastrophizing behavior and other patient reported outcomes measuring pain, physical distress, quality of life and mental/emotional well-being. This displays the importance of decreasing catastrophizing behavior in patients with anterior knee pain.
Exploring pain (Kujala) and physical distress (SF-12 PCS), we determined several social factors that affected these patient reported outcomes. Our study demonstrates the importance of addressing specific risk factors, including BMI and smoking habits, to limit the pain and dysfunction caused by their respective diagnosis. Ideally, once these factors are controlled, physical function and pain intensity will improve, thus decreasing catastrophizing behavior.14–19 Our study also found patients of Asian Indian ethnicity to experience more physical and mental distress than their Caucasian counterparts, suggesting the importance of counseling these patients directly after diagnosis to maintain optimal physical function.
Ultimately, the recognition of pain catastrophizing in patients presenting with knee pain can have significant implications on prognosis, treatment and recovery. For example, Tichonova et al.19 highlighted the role of psychological factors in rehabilitation after ACL reconstructions and meniscectomies— finding higher levels of pain catastrophizing to be significantly correlated with greater levels of postoperative knee pain. Perhaps most significant, they identified a decrease of the PCS over the course of treatment from 5.8 ± 0.9 to 4.2 ± 0.5 (p < 0.05), suggesting that pain catastrophizing may be modifiable with appropriate care.
According to Riddle et al.,5 patients scoring over 16 on the PCS were 2.67 times more likely to have a poor outcome (defined as less than 50% improvement) compared to patients with scores of 15 or less. Riddle et al.5 found that the pain catastrophizing score was the most powerful and consistent predictor for poor WOMAC pain outcomes and the only potential predictor for poor WOMAC function outcomes in a cohort of 140 patients undergoing total knee arthroplasty.5
Our study found that osteoarthritis patients with more symptoms, higher pain levels and physical dysfunction also had higher levels of catastrophizing behavior. This is a prime example of the strong correlation between catastrophizing behavior and its' direct physical effect on the human body. We have therefore determined it is vital for physicians to address the catastrophic thinking of all patients— especially osteoarthritis patients—due to the proximity to Riddle's threshold. Appropriate counseling is also recommended for specific ethnicities and patients with chronic pain, as both groups had a strong correlation with higher pain catastrophizing scores. We suggest beginning treatment quickly to decrease symptoms and improve outcomes.
Our results highlight the importance of addressing the patients’ biological, psychological and social needs because of the potential effects on physical quality of life. Additionally, the authors recommend the utility of behavioral interventions to reduce pain catastrophizing and thus accelerate the recovery process.
4.1 Limitations
Our study is not without limitations. First, this study was unable to make conclusions regarding causality—it remained unclear whether patients’ pain catastrophizing predated physical disability or was a secondary effect of pain. Similarly, due to lack of follow-up, we were unable to conclude whether and how pain catastrophizing behaviors impact function over time and with treatment. Second, there was no true asymptomatic control group available for study—all patients presenting to our clinic presented with complaints of pain, impaired physical quality of life, and/or some degree of psychological distress. Selection bias may also have played a role as patients were included only when they presented with both radiographs and MRI available. This subgroup may present several confounding variables including, but not limited to, better healthcare access, higher healthcare utilization, and/or increased symptom severity and chronicity when compared to patients without imaging. Third, we sought to describe the presence of pain catastrophizing for all patients presenting for their first orthopedic evaluation of knee pain. As a result, the study population includes a wide range of orthopedic pathologies. Lastly, while we screened for history of mental health illness and psychotropic drug use using questionnaires and retrospective chart review, it is likely that this data was incomplete due to the sensitivity of disclosing such information. However, the dominance of pain catastrophizing as a predictive factor in outcome as described by Riddle et al.5 mitigate this weakness.
5 Conclusion
Knee pain patients presenting to an orthopedic sports medicine clinic demonstrate diminished physical quality of life and psychological reserves. This study determined an association between catastrophizing behavior and other patient reported outcomes measuring pain, physical distress, quality of life and mental/emotional well-being. To optimize patient outcomes, the psychological domain should be managed contemporaneously to orthopedic pathology.
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