Patient-Reported Outcomes and Opioid Use by Outpatient Cancer Patients

Burden of drug use disorders in the United States from 1990 to 2021 and its projection until 2035: results from the GBD study

BACKGROUND

Drug use disorders (DUDs) have emerged as one of the most significant public health crises, exerting a substantial influence on both community health and socio-economic progress. The United States (US) also suffers a heavy burden, it is necessary to figure out the situation from multiple perspectives and take effective measures to deal with it. Therefore, using the data from the Global Burden of Diseases, Injuries, and Risk Factors (GBD) 2021, we evaluated this topic.

METHODS

Annual data on DUDs-related burden were collected from the GBD study 2021. We calculated the indicator of estimated annual percentage change (EAPC) to evaluate the changing trend of burden. The Bayesian model for age-period-cohort was introduced to forecast the burden.

RESULTS

In 2021, the number and age-standardized rate of prevalence were particularly prominent, with 12,146.95 thousand and 3821.43 per 100,000, respectively. Higher burden was also observed in males, 15-45 years old populations, and opioid use disorders subtype. From 1990 to 2021, the DUDs-related burden increased in the US and all states, especially in West Virginia; and the national death-related burden with the highest increase (EAPC = 7.96). Other significant inverse associations were seen between EAPC, age-standardized rates, and socio-demographic index (SDI). Moreover, in the next 14 years, the projected DUDs burden remains exigent.

CONCLUSIONS

The burden of DUDs in the US is heavy and has been enlarging. This study proposes that greater attention should be paid to the strategies in males, the younger population, opioid use disorders, and low-SDI states implemented by decision-makers to achieve goals such as reducing burden.

Association between trajectories of prescription opioid use and risk of opioid use disorder and overdose among US nonmetastatic breast cancer survivors

PURPOSE

To examine the association between prescription opioid use trajectories and risk of opioid use disorder (OUD) or overdose among nonmetastatic breast cancer survivors by treatment type.

METHODS

This retrospective cohort study included female nonmetastatic breast cancer survivors with at least 1 opioid prescription fill in 2010-2019 Surveillance, Epidemiology and End Results linked Medicare data. Opioid mean daily morphine milligram equivalents (MME) calculated within 1.5 years after initiating active breast cancer therapy. Group-based trajectory models identified distinct opioid use trajectory patterns. Risk of time to first OUD/overdose event within 1 year after the trajectory period was calculated for distinct trajectory groups using Cox proportional hazards models. Analyses were stratified by treatment type.

RESULTS

Four opioid use trajectories were identified for each treatment group. For 38,030 survivors with systemic endocrine therapy, 3 trajectories were associated with increased OUD/overdose risk compared with early discontinuation: minimal dose (< 5 MME; adjusted hazard ratio [aHR] = 1.73 [95% CI  1.43-2.09]), very low dose (5-25 MME; 2.67 [2.05-3.48]), and moderate dose (51-90 MME; 6.20 [4.69-8.19]). For 9477 survivors with adjuvant chemotherapy, low-dose opioid use was associated with higher OUD/overdose risk (aHR = 7.33 [95% CI 2.52-21.31]) compared with early discontinuation. For 3513 survivors with neoadjuvant chemotherapy, the differences in OUD/OD risks across the 4 trajectories were not significant.

CONCLUSIONS

Among Medicare nonmetastatic breast cancer survivors receiving systemic endocrine therapy or adjuvant chemotherapy, compared with early discontinuation, low-dose or moderate-dose opioid use were associated with six- to sevenfold higher OUD/overdose risk. Breast cancer survivors at high-risk of OUD/overdose may benefit from targeted interventions (e.g., pain clinic referral).

Should We Use COMM (Current Opioid Misuse Measure) to Screen for Opioid Abuse in Patients With Cancer Pain?

BACKGROUND

Growing concerns about opioid use disorder (OUD) and the resulting decrease in opioid availability for patients with cancer pain highlight the need for reliable screening tools to identify the subset of patients at increased risk for aberrant opioid use. Our study examines the utility of Current Opioid Misuse Measure (COMM) recommended by the NCCN Clinical Practice Guidelines in Oncology for Adult Cancer Pain.

PATIENTS AND METHODS

We analyzed prospectively collected patient-reported outcomes of 444 consecutive patients with cancer seen in pain clinics of a cancer center at 2 time points within 100 days. The relationship of COMM to other OUD screening tools, pain, opioid doses, patient demographics, and mortality was examined using univariate and multivariable logistic regression. We also examined individual items of COMM for face validity.

RESULTS

Among 444 patients who completed pain surveys at 2 time points, 157 (35.4%) did not complete COMM surveys. Using a COMM cutoff of ≥13, a total of 84 patients (29.3%; 84/287) scored positive for aberrant drug use. As patients remained on opioids for 49 to 100 days, the likelihood of improving COMM score (turning from positive to negative) was 6.1 times greater than the reverse. The number of patients with COMM ≥13 was 3.8 times higher than the number of patients with CPT diagnostic codes for OUD, 5.3 times higher than those with a positive urine drug screening, and 21 times higher than those with a positive CAGE (Cut Down, Annoyed, Guilty, Eye-Opener Questionnaire) score. COMM ≥13 was not associated with pain relief response (worst pain intensity score ≥2 points on the Brief Pain Inventory), opioid doses, gender, or age. Contrary to the intended use of COMM to identify aberrant opioid use, COMM ≥13 predicted mortality: patients with COMM ≥13 were 1.9 times more likely to die within 12 months.

CONCLUSIONS

Our study found that using COMM in a cancer population may significantly overestimate the risk of opioid misuse. Using COMM without modifications can create an additional barrier to cancer pain management, such as limiting appropriate opioid use.

Response Rates to Methylnaltrexone in Hospitalized Cancer Patients

Context: Methylnaltrexone is a peripherally-acting mu-opioid receptor antagonist studied in both cancer and non-cancer patients with opioid-induced constipation (OIC), but mostly in the outpatient setting. For adult hospitalized cancer patients with OIC, its effectiveness is unknown. Objectives: Describe the efficacy of methylnaltrexone for OIC in the inpatient setting, defined as bowel movement (BM) within 24 hours of methylnaltrexone administration. Methods: We performed a single-center, retrospective chart review of all hospitalized, adult patients with a cancer diagnosis who received methylnaltrexone from the palliative care team between January 1st, 2012 and July 1st, 2019. Results: We identified 194 patients. The mean age was 59, 50.5% were male and 88% were white. 192 patients (98%) received the 8 mg dose subcutaneously. The median oral morphine equivalent (OME) was 135 mg (IQR 70-354 mg). 45% (95% confidence interval, 38-53%) had a BM within 24 hours. Higher OME was correlated with successful BM, with a response in 93% (86/92) of patients receiving ≥150 OME and 2% (2/102) of patients receiving <150 OME (P < .0001). Prior laxative use did not predict response at 24 hours whether these were osmotic laxatives (40.7% vs 47.1%, P = .52), stimulant laxatives (45.7% vs 45.2%, P > .99), or stool softeners (44.7% vs 46.1%, P = .89). Conclusion: Methylnaltrexone has a high response rate when used as treatment for OIC in hospitalized adult cancer patients, especially for patients taking ≥150 OME.

Distinct Worst Pain Profiles in Oncology Outpatients Undergoing Chemotherapy

BACKGROUND

While pain is a significant problem for oncology patients, little is known about interindividual variability in pain characteristics.

OBJECTIVE

The aims of this study were to identify subgroups of patients with distinct worst pain severity profiles and evaluate for differences among these subgroups in demographic, clinical, and pain characteristics and stress and symptom scores.

METHODS

Patients (n = 934) completed questionnaires 6 times over 2 chemotherapy cycles. Worst pain intensity was assessed using a 0- to 10-point numeric rating scale. Brief Pain Inventory was used to assess various pain characteristics. Latent profile analysis was used to identify subgroups of patients with distinct pain profiles.

RESULTS

Three worst pain profiles were identified (low [17.5%], moderate [39.9%], severe [42.6%]). Compared with the other 2 classes, severe class was more likely to be single and unemployed and had a lower annual household income, a higher body mass index, a higher level of comorbidity, and a poorer functional status. Severe class was more likely to have both cancer and noncancer pain, a higher number of pain locations, higher frequency and duration of pain, worse pain quality scores, and higher pain interference scores. Compared with the other 2 classes, severe class reported lower satisfaction with pain management and higher global, disease-specific, and cumulative life stress, as well as higher anxiety, depression, fatigue, sleep disturbance, and cognitive dysfunction scores.

CONCLUSIONS

Unrelieved pain is a significant problem for more than 80% of outpatients.

IMPLICATIONS FOR PRACTICE

Clinicians need to perform comprehensive pain assessments; prescribe pharmacologic and nonpharmacologic interventions; and initiate referrals for pain management and psychological services.

Perturbations in Neuroinflammatory Pathways Are Associated With a Worst Pain Profile in Oncology Patients Receiving Chemotherapy

Unrelieved pain occurs in 55% of cancer patients. Identification of molecular mechanisms for pain may provide insights into therapeutic targets. Purpose was to evaluate for perturbations in neuroinflammatory pathways between oncology patients with and without severe pain. Worst pain severity was rated using a 0 to 10 numeric rating scale six times over two cycles of chemotherapy. Latent profile analysis was used to identify subgroups of patients with distinct pain profiles. Pathway impact analyses were performed in two independent samples using gene expression data obtained from RNA sequencing (n = 192) and microarray (n = 197) technologies. Fisher's combined probability test was used to identify significantly perturbed pathways between None versus the Severe pain classes. In the RNA sequencing and microarray samples, 62.5% and 56.3% of patients were in the Severe pain class, respectively. Nine perturbed pathways were related to neuroinflammatory mechanisms (i.e., retrograde endocannabinoid signaling, gamma-aminobutyric acid synapse, glutamatergic synapse, Janus kinase-signal transducer and activator of transcription signaling, phagosome, complement and coagulation cascades, cytokine-cytokine receptor interaction, chemokine signaling, calcium signaling). First study to identify perturbations in neuroinflammatory pathways associated with severe pain in oncology outpatients. Findings suggest that complex neuroimmune interactions are involved in the maintenance of chronic pain conditions. Perspective: In this study that compared oncology patients with none versus severe pain, nine perturbed neuroinflammatory pathways were identified. Findings suggest that complex neuroimmune interactions are involved in the maintenance of persistent pain conditions.

Time trends and associated factors of global burden due to drug use disorders in 204 countries and territories, 1990-2019

BACKGROUND

Drug use disorders (DUDs) have been a public health crisis which strongly impacted community health and socio-economic development. However, there are few studies based on the latest global data to show changes in the disease burden due to DUDs, specifically investigating associations between the country-level socio-economic factors and the burden of DUDs.

METHODS

Data of DUDs were extracted from the Global Burden of Disease Study 2019 database to explore the trends of the disease burden due to DUDs from 1990 to 2019. Univariate linear regression and stepwise multiple linear regression analysis were performed to analyze the correlations between burden due to DUDs and country-level socio-economic factors.

RESULTS

Globally, the number of disability-adjusted life-years (DALYs) caused by DUDs approximately increased by 2.6% yearly from 1990 to 2019, though the age-standardized DALY rate has not changed significantly in the past 30 years. The age-standardized DALY rate of opioid use disorders showed an upward trend during the past 30 years and was highest among 5 types of DUDs in 2019. Inequality-adjusted human development index (β = 15.9, 95% confidence interval [CI]: 12.9-18.9, P < 0.001) was identified as the key risk factor associated with square-root transformed age-standardized DALY rate of DUDs.

CONCLUSIONS

Global burden due to DUDs has increased significantly over the past 30 years. More effective targeted public health policies should be formulated to manage the public health challenge of DUDs, especially in developed countries and territories.

Opioid use by cancer status and time since diagnosis among older adults enrolled in the Prostate, Lung, Colorectal, and Ovarian screening trial in the United States

BACKGROUND

Dosing limits in opioid clinical practice guidelines in the United States are likely misapplied to cancer patients, however, opioid use may be difficult to ascertain as they are largely excluded from opioid use studies.

METHODS

The primary objective was to determine whether cancer patients were more likely to be chronic opioid users after diagnosis. We described prescription opioid use among U.S. older adult cancer patients during two time periods, within 2 years of diagnosis (short-term) and at least 2 years beyond diagnosis (long-term), compared to those without cancer (controls). Among participants in the Prostate, Lung, Colorectal, and Ovarian (PLCO) screening trial with linkages to Medicare Part D data during 2011-2015, we used multivariable logistic regression to estimate the association between cancer diagnosis and opioid use outcomes controlling for demographics. The primary outcome of opioid use was measured with the following metrics: Any opioid use, chronic use (90 consecutive days supply of opioid use while allowing for a 7-day gap between refills), high use (average daily morphine equivalent (MME) ≥120 mg for any 90-day period), and total MME dose above 2,000 mg (MME₂₀₀₀ ).

RESULTS

The short-term cohort included 1,491 cancer patients and 24,930 controls. Any use in the 2-year post-diagnosis period was higher among cancer patients OR 3.3 (95% CI: 3.0-3.7). Chronic use rates were similar by cancer status (4.6% vs. 3.8% for cases and controls, respectively). The long-term cohort included 4,377 cancer patients and 27,545 controls. Rates of any use were similar among cancer patients and controls (63% vs. 59%).

CONCLUSIONS

Any opioid use was similar among long-term cancer survivors compared to controls, but differed among short-term survivors for any opioid use and marginally for chronic opioid use.

Index and Nonindex Pain Endpoints in Radiation Therapy for Painful Tumors: A Secondary Analysis of a Prospective Observational Study

Purpose

Improving pain interference in daily activities, rather than mere pain reduction, is a desirable endpoint for palliative radiation therapy. The association between pain response and pain interference has been studied almost exclusively in patients with painful bone metastases (PBMs), whereas nonindex pain has scarcely been explored in palliative radiation therapy. We investigated whether index and nonindex pain endpoints are associated with pain interference changes in patients with both PBMs and painful non-bone-metastasis tumors (PNTs).

Methods and Materials

Brief pain inventory data collected at baseline and at 2 months post-treatment were used to calculate differences in pain interference scores. Pain response in terms of the index pain was assessed using the international consensus endpoint. Patients were diagnosed with predominance of other pain (POP) if nonindex pain of malignant or unknown origin was present and had a greater pain score than the index pain.

Results

Of 302 patients, 127 (42%) had PBMs and 175 (58%) had PNTs. The median pain interference score, which is based on the mean of the 7 subscale items, decreased to a greater extent among responders than among nonresponders (PBM group: –3.43 vs –0.57 [P = .005]; PNT group: –2.43 vs –0.29 [P < .001]). Moreover, patients without POP experienced a greater reduction in their median pain interference score than did those with POP (PBM group: –2.71 vs +0.43 [P = .004]; PNT group: –2.00 vs +1.57 [P = .007]). The Jonckheere-Terpstra test showed a significant trend across 4 pain response categories in patients with PBMs and those with PNTs (P < .001 for both).

Conclusions

The index and nonindex pain endpoints were positively and negatively associated with improvement in pain interference, respectively. There was no apparent difference between patients with PBMs and PNTs in terms of the associations of these endpoints with pain interference.

Successful use of buprenorphine-naloxone medication-assisted program to treat concurrent pain and opioid addiction after cancer therapy

Cancer pain is often treated with opioids, a therapeutic regimen that can become a challenge in patients with an opioid use disorder (OUD). While use of the buprenorphine-naloxone combination is an effective medication-assisted treatment (MAT) for OUD, its use in pain patients with OUD has been controversial due to concerns that co-administration of buprenorphine can reduce or block analge-sia and precipitate opioid withdrawal in those patients requiring full opioid agonists. Data on its use in cancer pain patients are lack-ing. In this case series, the authors explore the frequency of buprenorphine-naloxone use and its outcomes in patients in a Compre-hensive Care Center (CCC) Pain Registry. OUD was deduced from an International Classification of Diseases (ICD-10) diagnostic code for opioid-related disorders recorded in the electronic medical records. Of 2,320 chronic cancer pain patients, 125 patients had ICD-10 code for opioid-related disorders, and 43 had a diagnosis of opioid abuse of whom 11 received buprenorphine-naloxone combina-tions. Eight patients on 18 (6-24) mg per day of buprenorphine-naloxone remained in therapy for 4 (2-7) years without opioid abuse relapse. This assessment was based on clinician's notes, the Prescription Monitoring Program, random urine drug screening, and the absence of Urgent Care Center visits for opioid withdrawal or overdose. When short-term opioids were administered for acute pain, these patients were able to taper down and stop them quickly without an opioid abuse relapse. Buprenorphine-naloxone was effec-tive as the sole analgesic in selected patients. Given its success at the CCC, buprenorphine-naloxone should be made available and strongly considered as a treatment for patients suffering from OUD during and following cancer treatment and when cancer pain re-duces or resolves.

Patterns of opioid use in older people diagnosed with cancer in New South Wales, Australia

PURPOSE

Opioids provide effective analgesia for most cancer patients, but little is known about individual-level opioid use after cancer diagnosis. We examined the patterns of and factors associated with opioid use in older people diagnosed with cancer.

METHODS

We used the Department of Veterans' Affairs (DVA) client data linked with the New South Wales (NSW) Cancer Registry and the Repatriation Pharmaceutical Benefits Scheme data. We included people aged ≥65 years diagnosed with cancer in NSW, Australia in 2005 to 2015. We examined patterns of opioid use in the 12 months after cancer diagnosis and used cause-specific hazards models to examine factors associated with opioid use.

RESULTS

Of 13 527 people diagnosed with cancer, 51% were dispensed opioids after their diagnosis. We observed the highest proportions of use in people diagnosed with pancreas, liver, or lung cancers. Opioid use was associated with female sex, younger age, more advanced degree of cancer spread, opioid use before cancer diagnosis, and multimorbidity. Forty-four percentages of all people dispensed opioids had a history of opioid use in the 12 months before their cancer diagnosis; these people had higher median number of different opioids and opioid dispensings, and a shorter time to first opioid dispensing than opioid-naive people.

CONCLUSION

Our study suggests that many older cancer patients were dispensed opioids before their cancer diagnosis. Previously opioid-treated people had more intense opioid use patterns after diagnosis than opioid-naïve people. Acknowledging the history of opioid use is important as it may complicate pain treatment in clinical practice.

Patterns of Opioid Prescribing among Medicare Advantage Beneficiaries with Pain and Cardiopulmonary Conditions

Background: Pain is common among patients with cardiopulmonary conditions; however, there are increasing concerns, but limited research, regarding use of opioids for pain in patients with noncancer conditions. Objective: To compare patterns of opioid prescribing among older adults reporting pain with cardiopulmonary conditions and/or cancer. Design: Observational study using data from the Surveillance, Epidemiology, and End Results-Medicare Health Outcomes Survey resource linked to Medicare Part D prescription claims. Setting/Subjects: We identified patients who self-reported moderate-to-severe pain interference with daily activities. Patients were stratified by (1) self-reported history of cardiopulmonary conditions; (2) were within five years of cancer diagnosis; (3) had both conditions; or (4) neither. Measurements: We characterized opioid prescribing within 30 days of survey and one-year follow-up using logistic regression and Cox proportional hazard time-to-event analyses. Results: Of 10,516 patients with moderate-to-severe pain (1758 cardiopulmonary conditions, 3383 cancer, 2861 both, 2514 neither), 46% were aged ≥75 years, 65% were non-Hispanic white, and 10% non-Hispanic black. At survey, 1627 (15.5%) received opioids. Adjusted proportions of opioid use were lower for patients with cardiopulmonary conditions only (14%) compared with cancer only (17%; p < 0.001) and both conditions (17%; p < 0.001) but higher than patients with neither condition (13.1%; p < 0.001). There was no difference in time to initiation of opioids at follow-up among patients with cardiopulmonary conditions only, relative to cancer only (adjusted hazard ratio 1.03; 95% confidence interval 0.88-1.21). Conclusions: Opioid use is lower among patients with pain and cardiopulmonary conditions relative to patients with cancer. Findings emphasize the importance of pain assessment and management for patients with cardiopulmonary conditions.

Patterns of pain medication use associated with reported pain interference in older adults with and without cancer

CONTEXT

Concerns about the adequacy of pain management among older adults are increasing, particularly with restrictions on opioid prescribing.

OBJECTIVES

To examine associations between prescription pain medication receipt and patient-reported pain interference in older adults with and without cancer.

METHODS

Using the 2007-2012 Surveillance Epidemiology and End Results (SEER)-Medicare Health Outcomes Survey (MHOS) database linked to Medicare Part D prescription claims, we selected MHOS respondents (N = 15,624) aged ≥ 66 years, ≤ 5 years of a cancer diagnosis (N = 9105), or without cancer (N = 6519). We measured receipt of opioids, non-steroidal anti-inflammatory drugs, and antiepileptics, and selected antidepressants within 30 days prior to survey. Patient-reported activity limitation due to pain (pain interference) within the past 30 days was summarized as severe, moderate, or mild/none. Logistic regression using predictive margins estimated associations between pain interference, cancer history, and pain medication receipt, adjusting for socio-demographics, chronic conditions, and Part D low-income subsidy.

RESULTS

Severe or moderate pain interference was reported by 21.3% and 46.1%, respectively. Pain medication was received by 21.5%, with 11.6% receiving opioids. Among adults reporting severe pain interference, opioid prescriptions were filled by 27.0% versus 23.8% (p = 0.040) with and without cancer, respectively. Over half (56%) of adults reporting severe pain in both groups failed to receive any prescription pain medication.

CONCLUSIONS

Older adults with cancer were more likely to receive prescription pain medications compared with adults without cancer; however, many older adults reporting severe pain interference did not receive medications. Improved assessment and management of pain among older adults with and without cancer is urgently needed.

Does transdermal fentanyl work in patients with low BMI? Patient-reported outcomes of pain and percent pain relief in cancer patients on transdermal fentanyl

BACKGROUND

Low body mass index (BMI) is suspected of being associated with low transdermal fentanyl (TDF) blood levels and worse pain relief. Clinical pain data to support this claim are lacking.

METHODS

Using a Chronic Pain Registry, we identified 901 cancer patients who received TDF at outpatient pain service clinics of our cancer center from 7/1/2011 to 12/1/2016. Of these, 240 patients had a BMI measure, pain intensity, and pain relief scores documented within 30 days of a TDF order. We examined associations between BMI, TDF dose, Worst and Least pain scores, and pain relief scores using standard statistical tests.

RESULTS

In cancer patients receiving TDF, low BMI (<18.5) was significantly associated with greater pain relief irrespective of TDF dose and borderline significantly associated with greater percent pain relief after controlling for age, cancer diagnoses, and pain etiology (P = .073), suggesting that low BMI may independently predict better pain relief in cancer patients. As there were no significant associations between BMI and TDF dose, we find no basis for BMI-dependent dose modification or avoiding TDF in cachectic and low BMI patients.

CONCLUSIONS

When predicting percent pain relief, we conclude that there is no basis for avoiding TDF or modifying its dose in cancer patients with low BMI and cachexia.

Short- and Long-term Opioid Use in Patients with Oral and Oropharynx Cancer

OBJECTIVE

Opioid use and abuse is a national health care crisis, yet opioids remain the cornerstone of pain management in cancer. We sought to determine the risk of acute and chronic opioid use with head and neck squamous cell cancer (HNSCC) treatment.

STUDY DESIGN

Retrospective population-based study.

SETTING

Surveillance, Epidemiology and End Results (SEER)-Medicare database from 2008 to 2011.

SUBJECTS AND METHODS

In total, 976 nondistant metastatic oral cavity and oropharynx patients undergoing cancer-directed treatment enrolled in Medicare were included. Opiate use was the primary end point. Univariate and multivariable logistic analyses were completed to determine risk factors.

RESULTS

Of the patients, 811 (83.1%) received an opioid prescription during the treatment period, and 150 patients (15.4%) had continued opioid prescriptions at 3 months and 68 (7.0%) at 6 months. Opioid use during treatment was associated with prescriptions prior to treatment (odds ratio [OR], 3.28; 95% confidence interval [CI], 2.11-5.12) and was least likely to be associated with radiation treatment alone (OR, 0.35; 95% CI, 0.18-0.68). Risk factors for continued opioid use at both 3 and 6 months included tobacco use (OR, 2.23; 95% CI, 1.05-4.71 and OR, 3.84; 95% CI, 1.44-10.24) and opioids prescribed prior to treatment (OR, 3.84; 95% CI, 2.45-5.91 and OR, 3.56; 95% CI, 1.95-6.50). Oxycodone prescribed as the first opioid was the least likely to lead to ongoing use at 3 and 6 months (OR, 0.33; 95% CI, 0.17-0.62 and OR, 0.26; 95% CI, 0.10-0.67).

CONCLUSION

Patients with oral/oropharyngeal cancer are at a very high risk for receiving opioids as part of symptom management during treatment, and a significant portion continues use at 3 and 6 months after treatment completion.

Predictors of the Predominance of NonIndex Pain After Palliative Radiation Therapy for Painful Tumors

Purpose

Even when index pain (pain caused by the irradiated tumor) is palliated after radiation therapy (RT), patients may not derive the full benefits of RT in the presence of another, more intense pain. In this case-control study with prospectively collected data, we sought to identify predictors of the predominance of nonindex pain after palliative RT.

Methods and Materials

Brief Pain Inventory data were collected from patients who received RT for painful tumors. The treating radiation oncologists prospectively evaluated the intensity and origin of nonindex pain. Patients were diagnosed with predominance of other pain (POP) if nonindex pain of malignant or unknown origin was present and had a greater worst pain score than the index pain at the 1- or 2-month follow-up. Changes in pain interference from baseline to follow-up were compared between the 2 groups using Mann-Whitney U tests. Using variables that were identified as significant in a multivariable logistic regression analysis, we developed a prediction model for POP.

Results

Of the 170 patients who were evaluable at the 2-month follow-up, 24 (14%) were diagnosed with POP. At the 2-month follow-up examination of the patients with POP, none of the items of the pain interference scores were reduced from baseline; in contrast, patients without POP experienced significant reductions in all items. Multivariable analysis using the backward elimination method indicated that age ≤65 years, the presence of nonindex pain of malignant or unknown origin at baseline, and no opioid analgesic use at baseline were significant independent predictors of POP. As the number of the risk factors increased, the proportion of patients with POP increased.

Conclusions

We identified three predictors of POP. For patients likely to have POP, careful follow-up is important, and new palliative RT or analgesics should be used when needed.