This study examined chronic pain prevalence, health service utilization, and pain treatment experience among a sample of U.S. military veterans with HCV infection. Nearly two-thirds of participants reported having been diagnosed with chronic pain and had corroborating pain diagnoses in their medical records. This finding is in line with prior studies that have estimated prevalence of chronic pain among patients with HCV to range from 67%–83% (5
). Among participants diagnosed with chronic pain, 84% had two or more diagnoses of pain documented in the medical record.
Compared to participants with HCV but no chronic pain, veterans with comorbid HCV and chronic pain reported lower physical quality of life and utilized more health services including number of inpatient hospital stays and number of days on inpatient psychiatric wards, even after adjusting for demographic variables, comorbid medical conditions, disability indicators, liver disease severity indicators, depression, PTSD, and substance use covariates. In addition, participants with chronic pain had more total outpatient visits with primary care providers, physical therapists, occupational therapists, and specialty pain providers. These findings indicate that pain is associated with increased health service utilization among patients with HCV. The extensive use of both inpatient and outpatient services by patients with comorbid HCV and chronic pain has significant cost implications, particularly considering that pronounced health service use disparities between patients with and without chronic pain were evidenced with inpatient hospital stays, which incur the greatest cost to a medical organization and the greater healthcare system.
Exploratory descriptive data on past pain treatment use indicated that patients with HCV and chronic pain had tried a significant number of pain treatments in the past, with over 90% reporting prior use of pharmacotherapy, including prescription opioid medications. Others have observed lower rates of pharmacotherapy use in the past 12 months among both non-veteran and veteran patients with chronic pain. For example, 33% of patients with chronic pain identified through a population survey were currently taking analgesic medication to manage pain (40
). Among U.S. veterans with chronic pain, 41% were prescribed opioid medication by a VA provider over a 12-month prospective period (41
), while others have found that 30% of U.S. veterans with comorbid HCV and chronic pain were prescribed opioid medication in the past 12 months (8
). In the current study, we assessed reported lifetime use of pharmacotherapy, which likely accounts for the higher proportion of patients reporting pharmacotherapy for pain management.
Although 90% of participants reported past use of prescription opioids, fewer (56%) reported current use. The reasons for reduced usage of opioids among these patients remain elusive due to limitations in our data. It is possible that opioids may have been discontinued for a number of reasons, including medication side effects, limited analgesia, concurrent substance use, or some other factor. Providers may be reticent to prescribe opioid medications to patients with histories of alcohol or substance abuse (42
), of which this patient sample was almost entirely comprised. Alternatively, some patients may choose not to take opioids due to concerns about potential addiction, despite providers’ willingness to prescribe these medications. Still other patients may have undergone trials of opioid medications in the past, but had little pain relief and/or experienced significant medication-related side effects (44
Many non-pharmacological pain treatments had also been used by the majority of patients with chronic pain in the current study, albeit to a lesser extent than pharmacological pain treatments, perhaps due to disproportional referrals made by providers for pharmacological and non-pharmacological pain treatments (45
), although data were not available in our study to assess rates of referral. The moderately high rates of non-pharmacological pain treatment use by patients with comorbid HCV and chronic pain is consistent with findings from non-veteran samples of patients with chronic pain, which indicate that the majority of patients report prior or current use of various complementary pain management treatments (e.g., chiropractic, massage, acupuncture; 46). This reported use of various non-pharmacological pain treatment strategies may be due to the accessibility and affordability of these treatments for veterans within the VA system such as physical therapy, TENS, and cognitive-behavioral therapy for chronic pain.
This study has several limitations. Namely, this study was conducted exclusively with U.S. military veterans treated at a single hospital within the VA healthcare system, and results may not generalize to other populations of patients with HCV. In addition, patients with HCV in this study did not have advanced liver disease or had not been diagnosed with hepatocellular carcinoma. We also excluded participants who had been treated with interferon for HCV. As such, it is unclear if findings on increased medical service utilization for patients with comorbid HCV and chronic pain would be replicable in a sample of patients with HCV that is more representative of the full HCV disease severity and treatment spectra.
We extracted data from a single VA hospital system and did not account for the possibility that participants may have received medical care at other VA or non-VA hospitals, and we are thus limited in our ability to interpret medical service utilization. In addition, we did not employ an HCV-negative control group to test whether HCV and chronic pain has a cumulative effect on health service utilization. Future studies could employ such four-group designs (i.e., HCV-negative without chronic pain, HCV-negative with chronic pain, HCV-positive without chronic pain, and HCV-positive with chronic pain), selecting random, rather than convenience, samples of patients with HCV and obtain health service data from multiple medical sources to evaluate this research question.
An additional limitation concerns the cross-sectional nature of this study. As such, the presence of pain cannot be said to cause increased use of health services. A prospective longitudinal study would be required to provide further evidence of this relationship. Furthermore, we did not evaluate the extent to which chronic pain contributed to a given inpatient or outpatient medical encounter, and future studies should help elucidate the relative contributions of pain to medical treatments received.
Finally, data on past pain treatment use were limited in several ways. Our data should be viewed as preliminary as we could not elucidate patterns of past chronic pain treatment use, acceptability of treatments used in the past, or reasons for discontinued use. Future studies should employ treatment use measures that can fill this existing gap in the literature.