https://orcid.org/0000-0002-5854-7549
ABSTRACT
Objective
To evaluate healthcare resource utilization (HCRU) by osteoarthritis (OA) pain severity.
Methods
Cross-sectional surveys of US physicians and their patients were conducted between February and May 2017. Using the Numeric Rating Scale, patients were classified by self-reported pain intensity in the last week into mild (0–3), moderate (4–6), and severe (7–10) cohorts. Parameters assessed included clinical characteristics, HCRU, and current caregiver support. Descriptive statistics were obtained, and analysis of variance and chi-square tests were performed.
Results
Patients (n = 841) were mostly female (60.9%) and white (77.8%), with mean age of 64.6 years. Patients reported mild (45.4%), moderate (35.9%), and severe (18.7%) OA pain. Mean number of affected joints varied by pain severity (range mild: 2.7 to severe: 3.6; p < 0.0001). Pain severity was associated with an increased number of physician-reported and patient-reported overall healthcare provider visits (HCPs; both p < 0.001). As pain increased, patients reported an increased need for mobility aids, accessibility modifications to homes, and help with daily activities due to functional disability. The number of imaging tests used to diagnose OA was similar across pain severity but varied when used for monitoring (X-rays: p < 0.0001; computerized tomography scans: p < 0.0447). Hospitalization rates for OA were low but were significantly associated with pain severity (mild: 4.9%; severe: 11.5%). Emergency department visits were infrequent but increasing pain severity was associated with more prior and planned surgeries.
Conclusion
Greater current pain was associated with more prior HCRU including imaging for monitoring progression, HCP visits including more specialty care, hospitalizations, surgery/planned surgery, and loss of independence due to functional disability. Yet rates of hospitalizations and X-ray use were still sizable even among patients with mild pain. These cross-sectional findings warrant longitudinal assessment to further elucidate the impact of pain on HCRU.
1. Introduction
Osteoarthritis (OA) is a chronic, degenerative joint disease that is often accompanied by pain, stiffness, and impaired mobility. It is the most common musculoskeletal disorder affecting the United States (US) population [Citation1]. Globally, the incidence of OA is predicted to rise [Citation2–4], due in part to aging populations and increasing obesity rates [Citation5]. A potential consequence of a rise in OA rates is an increasing burden on healthcare resources [Citation6]. Recent studies have shown that in the US, patients with OA utilized more healthcare resources compared to similar patients without OA in privately insured and a noninstitutionalized, nationally represented study sample [Citation7,Citation8]. This equated to increases in healthcare costs that were 4 times and 2.5 times higher in patients with OA versus without in the respective populations [Citation7,Citation8]. These burdens showed substantial variation by joint location with hip OA incurring the highest costs primarily due to all-cause inpatient costs [Citation7]. Similarly, a population-based study of Medicare beneficiaries found that patients with knee OA, compared with patients free of OA, showed increased healthcare resource utilization (HCRU) that was independent of comorbidity, and other patient characteristics [Citation9].
Pain is often a hallmark of OA, and a symptom that drives individuals to seek medical attention, contributes to functional limitations, reduces quality of life, and has an impact on HCRU [Citation10]. Examining the impact of OA pain severity on HCRU in real-world clinical practice settings is of growing importance given current OA disease trends. To our knowledge, only two studies have assessed the association between pain severity and HCRU in the US. In 2009, the National Health and Wellness Survey reported that among employed respondents with greater self-rated OA pain severity there was a corresponding increase in both prior direct and indirect healthcare costs [Citation11]. More recently, a review of claimants with OA within US commercial and Medicare Advantage insurance databases demonstrated that there is a positive association between increased pain severity scores and HCRU in the 3 months following the pain assessment [Citation12]. The objective of the current study was to evaluate the association of patient-reported OA pain severity in the last week with prior utilization of healthcare resources in routine clinical practice. In this study, the relationship between pain severity and HCRU could be assessed in a more direct manner than was possible using insurance claims data and from both the patient and physician’s perspective.
2. Methods
2.1. Study design
This study assessed the management of OA in routine clinical practice via a non-interventional, point-in-time, cross-sectional survey capturing current and past patient data from physicians and their patients. Data collection followed the methodology of the Adelphi Disease Specific Programme (DSP™) [Citation13]. The OA DSP has received a waiver by the Western IRB. The current analysis included data for patients with OA treated in the US between February and May 2017.
2.2. Participants and selection
Participating physicians were identified from public lists of healthcare providers (HCPs) according to pre-defined selection criteria: they were in one of three specialties (orthopedic surgery, rheumatology, primary care physicians [PCP]) and made treatment decisions for at least 10 patients with OA in a typical month. Candidate respondents were screened by telephone and those who met eligibility criteria were invited to participate. Physicians completed electronic patient record forms (PRFs) for their next nine consecutive patients.
Patients were eligible for inclusion if they had a confirmed diagnosis of OA, were aged 18 years or older, and had provided written informed consent. These patients were invited to fill out patient self-completed paper questionnaires (PSCs).
Patients were grouped by pain severity based on self-reported average pain intensity of all OA-affected joints over the last week using the 11-point Numeric Rating Scale (NRS; 0‒10) with scores of 0‒3 representing mild, 4–6 moderate, and 7‒10 severe pain. This grouping has been widely used in clinical studies and routine practice [Citation14,Citation15].
2.3. Outcome measures
The study used data derived from patients and physicians. Patient-reported outcome measures, captured by PSCs, provided information on time since OA diagnosis, pain severity in the last week, and current level of caregiver support.
Physician-reported outcome measures, captured by PRFs, provided information on patient demographics, clinical characteristics, number of affected joints, location of the ‘most troublesome joint’ from the physician’s perspective, and comorbid conditions at the time of the visit. Measures of obesity were captured from the patient’s charts using Body Mass Index (BMI) from the patient’s records and any diagnosis of obesity noted by the physician in the patient’s chart.
These patient- and physician-reported data also were used to quantify HCRU in OA. Information given by patients included: all physician specialty types ever involved in their OA treatment; number of clinic visits by specialty over the last 3 months; and the use of physical aids. For their part, physicians referred to patient records to document physician specialties involved at different stages of the treatment pathway, including who first saw the patient with suspected OA, who confirmed the diagnosis, and who initiated treatment. Physicians listed past and planned OA-related procedures for each patient; they also documented use of imaging tests for diagnosis and monitoring of OA, as well as rates of OA-related emergency department (ED) visits and hospitalizations over the last 12 months.
2.4. Statistical analysis
Descriptive and inferential analyses were conducted in this study. Frequencies, means, and standard deviations (SD) are reported for continuous variables [Citation16], and frequencies and percentages for categorical variables. Pain severity groups were compared using analysis of variance and chi-square tests (two-sided with p < 0.05) [Citation16]. The Fisher-Halton-Freeman exact test was used to compare variables with frequency counts that had an expected value ≤ 5 [Citation17]. While the descriptive analyses align with exploratory research, the inferential analyses (with hypothesis testing and p-values) align with inferential research. All data were managed and analyzed using SPSS v7.5 and Stata v14.1.
3. Results
3.1. Patient demographics and clinical characteristics
A total of 841 patients with self-reported pain severity data based on the NRS scale were included in this analysis. Overall, 498 (59.2%), 218 (25.9%), and 125 (14.9%) patients, consulted by PCPs, rheumatologists, and orthopedic surgeons, respectively, were included in this analysis. Patient demographics and clinical characteristics are shown in . Patients were mostly female (60.9%), white/Caucasian (77.8%), and employed (42.9%), and had a mean (SD) age of 64.6 (11.7) years. Patients were diagnosed with OA an average (SD) of 2.3 (3.8) years. In total, 382 (45.4%), 302 (35.9%), and 157 (18.7%) patients reported mild, moderate, and severe OA pain in the last week, respectively.
Table 1. Demographics and clinical characteristics by pain severitya
Current pain severity was associated with age, gender, employment status, BMI, number of joints affected, and area of the ‘most troublesome joint’ (all p < 0.05). Patients with greater pain were more likely to be older and have a higher BMI, as well as an increased number of joints affected. As pain severity progressed from mild to moderate and severe, the proportion of patients classified as obese (≥30 BMI) increased from 27.0% to 40.1% and 46.5%, respectively ().
The number of joints affected by OA increased from a mean (SD) of 2.7 (2.1) joints in patients with mild pain, to 3.4 (2.7) and 3.6 (2.8) joints in patients with moderate and severe pain, respectively. In terms of the ‘most troublesome joint’, knee OA was reported most frequently by physicians for all pain severity groups (43.0% of overall sample) but there was no significant difference in the rate of knee OA across pain severity groups. In contrast, there were significant differences in the percentage of patients across pain severity groups identifying back, hip, and hands/fingers as the ‘most troublesome joints’ affected by OA. The rate of physician-reported back OA as the ‘most troublesome joint’ increased from 16.2% in patients with mild pain to 25.5% in those whose pain was severe. In patients with hip OA as the ‘most troublesome joint’ the rate increased from 14.1% in patients with mild pain to 21.7% in the group with severe pain (). In contrast, the percentage of patients with hands/fingers as the ‘most troublesome joint’ was highest in the mild compared with the moderate and severe pain groups (12.3%, 6.0%, and 7.0%, respectively).
Patients often had comorbid conditions; most common were hypertension (56.7%), dyslipidemia (24.3%), anxiety (16.4%), depression (15.5%), and diabetes (15.3%) (). Of these five conditions, only hypertension, depression, and anxiety were significantly different across the pain severity groups (all p < 0.05). Hypertension was seen in most patients and ranged from 50.0% of those with mild pain to 62.6% of those with moderate pain. Even greater variability across pain severity groups was observed for depression and anxiety. Dyslipidemia and diabetes varied less across pain severity groups. Other comorbidities occurring in more than 5% of patients overall and differing across pain severity groups (mild, moderate, severe, respectively) were thyroid disease (9.7%, 16.2%, 12.7%), chronic lower back pain (5.2%, 22.2%, 17.2%), obesity (6.3%, 11.6%, 12.7%), and osteoporosis (4.7%, 11.9%, 17.2%) ().
Table 2. Comorbid conditions according to OA pain severitya
3.2. OA-related visits to healthcare providers
Prior visits to HCPs were recorded in the PSCs and PRFs (). Patients reported that a wide range of HCPs were historically involved in their OA treatment. There was an association between pain severity groups and number of patients previously treated by rheumatologists, chiropractors, pain specialists, neurologists, podiatrists, and physician assistants (all p < 0.05); rates tended to rise as pain severity increased. Conversely, a higher percentage of patients in the mild pain group saw occupational therapists compared with patients in the moderate and severe pain groups (7.3%, 2.0%, and 3.8%, respectively).
Table 3. Consultations with HCPs by pain severitya
Over the last 3 months, the average total number of patient-reported HCP visits for OA differed across pain severity groups (p < 0.0001), with means (SD) of 2.7 (3.5), 3.2 (3.0), and 5.1 (7.2) visits for patients with mild, moderate, and severe pain, respectively. Patient-reported HCP visits showed that PCPs saw the most patients (n = 597), with a mean (SD) number of 1.5 (1.1) visits. Fewer patients were seen by rheumatologists (n = 237), with a mean (SD) of 1.4 (1.0) visits, while for orthopedic surgeons (n = 278) the mean (SD) number of visits was 1.3 (1.1). The only other HCPs to see a significant number of patients were physical therapists (n = 113), with a mean (SD) number of 3.5 (4.9) visits per 3-month period, respectively.
The mean (SD) number of physician-reported clinic visits for OA over the last 12 months was significantly associated with pain severity; however, when observing within specialties, only the number of visits to PCPs was significantly associated with pain severity (both p < 0.001). Other specialties saw a consistent number of patients across pain severity groups ().
Information about which HCPs were involved in a patient’s initial consultation, diagnosis of OA, and subsequent treatment were also recorded. Initial consultations of patients with suspected OA were reported to have mainly involved PCPs (80.7% of all patients) with little difference across pain severity groups (). In contrast, there were significant differences across the three groups (PCPs, rheumatologists, and orthopedic surgeons) in terms of initial diagnosis of OA and the first treatment. While PCPs most frequently diagnosed and initiated treatment, there was a trend toward increased care being provided by rheumatologists and orthopedic surgeons, particularly for patients with moderate or severe pain. OA was diagnosed by rheumatologists in 15.4% of patients with mild pain but this increased to 17.5% and 26.1% in patients with moderate and severe pain, respectively. For PCPs, diagnosis of OA was 72.3% of patients with mild pain but this fell to 64.9% and 59.2% in the moderate and severe pain groups, respectively (). Initiation of OA treatment followed a similar pattern. Across the three leading physician specialties involved in the treatment of OA patients, only rheumatologists showed a significant association of treatment with pain severity (p = 0.0176). There was also an increasing involvement of pain specialists, occupational therapists, neurologists, and chiropractors consistent with increasing patient-reported pain, although the number of patients consulting these specialists remained relatively low (<10%).
3.3. Imaging tests for diagnosis and monitoring of OA
X-rays, magnetic resonance imaging (MRI), and computerized tomography (CT) were used in the diagnosis and monitoring of OA (). Physicians reported that X-rays were used in 86.9% of patients in the diagnosis of OA; MRIs were employed in 15.8%, and CT scans in 1.9%. None of the diagnostic imaging tests was observed to differ significantly in their rates of use by pain severity group.
Table 4. Physician-reported OA-related procedures, ED use, and hospitalizations according to pain severitya
Imaging tests for monitoring OA progression were used in 62.8% of patients and varied by pain severity (p = 0.0019); rates ranged from 56.5% in the mild pain group to 69.5% and 65.0% in the moderate and severe pain groups, respectively (). When comparing the use of specific imaging tests for monitoring OA progression, current pain severity was significantly associated with prior X-ray and CT scan use (both p < 0.05) but prior use of MRI remained relatively constant at around 11.7%, with little variation across pain severity. X-rays were used in 48.2%, 64.9%, and 57.3% of patients with mild, moderate, and severe pain, respectively. CT scan was rarely used (0–1.3%).
3.4. Hospitalization, emergency department use, and surgery
Over the last 12 months, physicians reported that 7.2% of patients (n = 56) were hospitalized for OA, and only 3.5% (n = 27) had visited the ED for a reason related to their OA. Within the group of hospitalized patients, the use of intensive care units was low at 3.6%. Pain severity was significantly associated with hospitalizations for OA (p = 0.0281) while use of the ED and hospitalizations increased with severity (mild, moderate, and severe): for ED use, 2.4%, 4.0%, and 5.3%, respectively; and for hospital use, 4.9%, 8.1%, and 11.5%, respectively. Admission through the ED was not significantly associated with OA pain severity (p = 0.4855). Overall, the duration of hospitalization tended to be short at 2.8 (1.82) days and did not change with pain severity. ‘Surgery’ for OA was the most common reason for hospitalization in the past 12 months for 78.6% of all hospitalized patients. Physicians reported that 21.9% of patients had undergone a surgical procedure related to OA and that 29.7% of patients would require ‘surgery’ in the future. Greater current pain was associated with more surgical procedures both in the past (mild, moderate, and severe pain: 16.5%, 25.2%, and 28.7% of patients, respectively) and for future/planned surgery (mild, moderate, and severe pain: 12.6%, 42.1%, and 47.1%, respectively; ). When physicians were asked to list the type of surgery, joint replacement was the most frequently planned operation and increased from 29.2% in patients with mild pain to 29.9% and 45.9% in patients with moderate and severe pain, respectively. The number of joint replacements planned for the future was associated with pain severity (p = 0.0481); however, other planned procedures did not show significant increases according to pain severity ().
Figure 1. Physician-reported planned surgical proceduresa to be undertaken for OA
3.5. Patient-reported need for aids
Differences across pain severity groups were found across all patient-reported measures of the impact of OA on physical functioning (all p < 0.0001; ). Increases by pain severity group were seen in the impact of OA on physical mobility (38.6%, 70.3%, and 81.8% of patients in the mild, moderate, and severe groups, respectively); the need for mobility aids (20.6%, 38.3%, and 47.4%) and accessibility modifications made to homes (8.5%, 18.9%, and 30.8%). Responses from 453 patients showed that 35.3% of these patients needed walking aids such as a cane/walking stick, walking frame, or wheelchair to move around either inside or outside the home. Responses from 749 patients showed that 16.3% of patients had made modifications to their home because of OA, most commonly adapting the bathroom.
Figure 2. Patient-reported need for support due to OA according to patient-reported pain severity. All comparisons showed significant changes (p < 0.0001). Pain intensity was based on pain over the last week using the 11-point Numeric Rating Scale including mild (0–3), moderate (4–6), and severe (7–10) pain categories
also indicated that increases by pain severity group were seen in the percentage of patients needing help with daily activities (4.7%, 14.1%, and 30.7%). Of the overall 12.8% of patients (n = 98) that required support, the mean (SD) hours per week that family or friends helped was 17.8 hours (26.1; range: 0–168) and professional caregivers helped for 7.4 hours (18.4; range 0–100). Patient-reported caregiver hours per week, professional caregiver hours per week, and caregiver costs per month also were not significantly associated with pain severity. Caregiver hours per week ranged from a mean (SD) value of 8.4 (11.5), 19.2 (31.8), and 20.1 (23.6) hours in patients with mild, moderate, and severe pain, respectively. Professional caregiver hours per week were 7.4 (14.5), 4.8 (11.3), and 10.0 (25.2) hours in patients with mild, moderate, and severe pain, respectively. The reported mean (SD) cost per week for professional caregiver support ranged from US$304 (947) in patients with mild pain to US$28 (108) and US$175 (336) per month in patients with moderate and severe pain, respectively.
4. Discussion
This study provided an assessment of the association between patient-reported OA pain severity over the last week and prior HCRU and current caregiver support for patients seeking treatment for their OA in US clinical settings. Higher levels of pain were associated with more OA-related HCRU, observed via parameters including prior HCP visits, hospitalizations and surgery, and current use of caregiver support and mobility aids. Patients with greater pain levels had more functional disability, higher levels of comorbidity, and increased resource use compared with those with less pain. Pain severity was not associated with the number of prior tests performed at diagnosis, yet the rate of X-rays and CT scans performed as part of routine disease monitoring did vary. Our findings expand the breadth of HCRU measured in prior studies and include both patient- and physician-reported assessments.
Consistent with other recent studies that have addressed the relationship of current OA severity and HCRU cross-sectionally (in the months pre-severity assessment) [Citation8] and longitudinally (in the months post-severity assessment) [Citation12], both methods identified increased hospitalizations and OA-related HCP visits as positively associated with pain severity. Although hospitalizations for OA are infrequent, they represent a large proportion of the overall economic cost of OA management [Citation18]. Notably, although hospitalizations increased with pain severity, they were not absent in those with mild pain, with 4.9% hospitalized for OA within the last 12 months. While pain is the primary symptom of OA [Citation19], changes in symptoms and structural disease progression are highly variable, individualized, and not necessarily correlated [Citation20] yet may influence care and appropriate timing of surgery [Citation21,Citation22]. The use of the ED in this group of patients remained comparable to that seen in other contemporary OA populations, where rates ranged from 1.2% to 3.3% across pain severity levels [Citation12]. OA-related ED use tended to increase with pain severity, but only reached a level of significance when measured in the 3 months post-pain assessment (rates of 1.2%, 1.9%, 3.3%) [Citation12] and not in the 12 months pre-pain assessment (mild 2.4%, moderate 4.0%, severe 5.3%) reported in our study. This may be due to the large sample size available in the longitudinal assessment (n = 35,861 patients) [Citation12].
Consistency in findings from pre- and post-assessment may have implications for clinicians and researchers. Clinically, these findings may infer that self-report of pain in patients with OA may be static over time despite actively seeking care. Whether this is due to inadequate relief from current therapies, central sensitization of pain, interference with multiple comorbidities that have been found to exacerbate OA pain [Citation23], or underrepresentation of patients not seeking care due to stabilization or resolution of painful symptoms, needs further exploration. These findings also may infer there is greater flexibility in the proximal measurement of pain severity relative to economic outcomes, allowing greater use of real-world data sources such as pain scores in electronic medical records for observational research.
In our study, the number of patient- and physician-reported prior visits to HCPs varied by OA pain severity, particularly for PCPs. Specialty care visits showed less dependence on current pain severity, perhaps due to the restricted number of visits allowed within health plans or the limited accessibility of specialists. PCPs were central to patient care with most patients seeing a PCP upon first signs of OA symptoms, diagnosis, and treatment for OA regardless of pain severity. There was no indication that specialists saw patients within the severe pain cohort at the beginning of their treatment, but there was a significant trend toward increased OA diagnosis confirmation and initiation of treatment by rheumatologists in patients with moderate or severe OA. Over a 12-month period, the trend was for increasing involvement of rheumatologists and pain specialists in treatment, and this was associated with current pain severity. In this study, the number of clinic visits was higher when reported by patients than physicians. This could be due to recall bias by the patient or a fragmented healthcare system where patients see multiple physicians for pain without linked patient records.
In OA, pain is recognized as a key driver of increased HCRU [Citation10] where the demands on healthcare systems are diverse, ranging from diagnosis and monitoring of disease, to HCP visits, hospitalizations, and surgery as the end-stage of treatment [Citation10,Citation24]. Rates of past and planned future surgeries due to OA were strongly associated with current pain severity. Importantly, greater pain severity was associated with rates of prior surgery, with 16.5% of patients with mild pain ever having an OA-related surgery, compared with 25.2% and 28.7% of patients with moderate and severe pain, respectively. Not surprisingly, increasing current pain was associated with increasing anticipation of future surgical intervention (including 30% of patients), but even patients with mild pain were anticipated to need surgery at rates of nearly 10% during the next 12 months and nearly 20% after more than 1 year. Total joint replacement was the most commonly planned surgery. As the study population has on average 3 joints affected by OA, the presence of a prior surgery on a different joint may precipitate physicians to already be considering joint replacement for patients with mild pain. Alternatively, data from pooled cohort studies found that most patients had total knee replacement (TKR) >2 years after appropriate criteria were determined (83%) and 9% had TKR too early; age, BMI, race, mood, general health, and living alone were all factors in the timing of surgery [Citation25]. Another study found that pre-surgical pain was not related to post-surgical pain [Citation26] indicating that more factors should be involved in the decision for surgical intervention. Most recently, shared decision-making has been studied to shift the focus away from clinical assessment and incorporate patient-reported outcomes measures such as pain, function, and quality of life in the determination of the appropriate timing of surgery [Citation27]. This study did not assess the proportion of patients who were contemplating surgery though not yet planned or the portion that accept the physician’s recommendation for surgery.
In addition to traditional HCRU, assessment of imaging provided new information in that diagnostic tests did not vary with pain severity yet subsequent X-rays and CT scans for monitoring disease progression were used more frequently in patients with moderate and severe pain than those with mild pain. High use of X-rays for diagnosis (87% of patients) is perhaps expected given that the American College of Rheumatology (ACR) [Citation28] support diagnosis of OA based a combination of factors including a patient’s age, physical examination, and radiographic and/or laboratory evidence. Monitoring via radiological assessment of OA to classify the degree of joint deterioration is used to determine the timing or necessity of surgical intervention, but are not part of disease management guidelines in the US [Citation29,Citation30]. These findings are also not surprising given that radiography is the most commonly used imaging technique, yet the value of other imaging methods are emerging particularly to assess progression [Citation31]. MRI scans were used more often than CT scans for both diagnosis and monitoring, and their use appeared independent of pain severity.
Other studies suggested MRI may have some advantages in early diagnosis of OA, but guidelines do not currently recommend its use as standard practice [Citation32,Citation33]. MRI is more costly than other tests which may limit their use [Citation34]. Given that the above analysis pre-dates this current analysis, results for the population assessed here suggest that routine clinical practice involves the considerable use of MRI in around 15% of patients.
Resources needed due to functional disability were a key issue especially as pain increased. Walking aids were required by 10-fold more patients with severe pain versus mild pain, and home modifications and caregiver support were required more by patients with severe pain than those with mild pain. Nearly one-third of patients with severe pain required caregiver support whereas these rates were 14% and 5% of patients with moderate and mild pain, respectively; however, among those needing support, the number of hours provided by caregivers varied widely and appeared independent of pain severity, indicating that other factors such as social support and financial ability may play a role in aiding patients. When the total cost of OA pain management is considered, caregiver burden and costs of aids may be overlooked, yet they represent a sizable proportion of costs to patients and healthcare systems. Assessment of nonsurgical therapies (over the counter or prescription medications and nonpharmacologic treatments) for OA pain was not part of these analyses but may be similarly relevant and deserves further attention.
The strengths of this study include a relatively large sample (n = 841) of patients drawn from real-world clinical practice, and HCRU data directly related to OA pain severity. Other studies using administrative insurance claims are inexact in attributing HCRU to a specific diagnosis [Citation12,Citation35] and may underrepresent key factors. For example, we found that both measures of obesity were associated with pain severity, yet only 10% of patients had a diagnosis of obesity (6.3% to 12.7% of mild to severe pain patients) whereas rates using BMI ranged from 27% to 46.5% of mild to severe pain patients. Although we did not study all-cause HCRU, several of the comorbidities seen in this study population were associated with pain severity, i.e., hypertension, coronary heart disease, osteoporosis, obesity, and constipation. Notably, these are associated with immobility. There was also an association between emotional disorders such as depression, anxiety, and insomnia and pain severity, with increasing number of patients with severe pain having such disorders than those with mild or moderate pain.
5. Limitations
The study has some limitations. The descriptive results and conclusions are intended to generate hypotheses for confirmation in future research; the inferential results (with p-values) also require confirmation. Thus, all comparisons should be investigated in future studies with the intent to substantiate or verify results and conclusions made in this article. Study patients represent only those actively seeking treatment for OA, and may over-represent well-motivated or better functioning patients. However, the clinical characteristics of these patients seem comparable to other contemporary OA populations in terms of age, gender, comorbidities, and number of affected joints [Citation12]. This study may have been affected by selection bias. Firstly, physician participation may have been based on personal workload, levels of consulting patients during the study period, or familiarity with the research nature of the study. The sample of patients was drawn from this small number of US physicians who may not be representative of all OA-treating specialties (e.g., pain specialists) or physicians within specialties thus leading to potential patient selection bias. Although this was limited through inclusion of consecutive patients, it could result in only certain types of patients as seen by treating physicians. The large sample size associated with this research is a major strength of the study; however, as with any real-world cross-sectional, observational research, missing data are an inherent limitation. For example, medical charts may be missing key out of network healthcare use and patients may be impacted by recall bias. To maintain ‘real world’ settings, diagnosis was based on the responding physician’s judgment and diagnostic skills rather than on a formalized diagnostic checklist. Finally, these data represent a cross-sectional assessment of current pain with report of prior HCRU and subsequent caregiver burden. Interestingly, higher current pain levels were associated with increased prior HCRU, which could suggest that despite visits to ED, hospitalizations, and surgical procedures, the pain level doesn’t improve much. Longitudinal studies should examine this. Additional studies to understand the causal relationship between changes in pain with changes in economic burden including HCRU and caregiver support is warranted.
6. Conclusions
For OA patients there is a clear association between pain severity and multiple patient activities and procedures related to HCRU. In this study, patients with increased pain were older with more affected joints and comorbidities, all of which may require increased HCRU. Pain severity was associated with subsequent increased functional disability, more support from caregivers, and more planned surgeries. Physician-reported prior HCRU increased with pain severity including more patient visits to HCPs, especially to PCPs, more frequent tests to monitor OA progression, increased hospital admissions, and prior surgeries. Characterizing subsets of patients by OA pain severity may provide greater understanding of unmet medical need for patients and the heterogeneity of patients with OA seen in clinical practice settings. Understanding the relationship between OA pain severity and HCRU may help to direct future areas of investigation for predicting the possible course of OA.
Declaration of interest
No potential conflict of interest was reported by the authors.
Declaration of financial/other relationships
All authors actively assisted in the study design and interpretation of data; contributed in writing this paper; and have provided final approval of submitted version. SN is a consultant/speaker and received honorarium from Pfizer and Eli Lilly and Company. The following authors are employees and minor stockholders of Eli Lilly and Company: RLR and LV. JCC, AGB, and LT are employees of Pfizer with stock and/or stock options. JM, JJ, and NH are employees of Adelphi Real World who were paid consultants to Pfizer and Eli Lilly and Company for this study and development of this manuscript. Writing support by David Whitford of Sapitwa Communications was funded by Pfizer and Eli Lilly and Company. Editorial support, consisting solely of copyediting and formatting, was provided by Diane Hoffman, PhD, of Engage Scientific Solutions and was funded by Pfizer and Eli Lilly and Company.
Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.
Acknowledgments
The findings of this manuscript have been presented in part at the 12th Annual Meeting of PAINWeek, September 4–8, 2018, Las Vegas, NV and American Pain Society meeting April 3‒6, 2019 Milwaukee, Wisconsin. The authors would like to thank David Whitford, Sapitwa Communications Limited for writing support and Engage Scientific Solutions for editorial support.
Data availability
Adelphi Real World was responsible for the analyses and house the data.
Additional information
Funding
References
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