Background: The problem of cancer-related pain is well established. Chronic pain (persisting > 3 months) in cancer patients is less well characterized. We have previously shown that cancer patients referred to pain clinics in Australia and NZ have similar pain to other people with chronic pain.1 Primary objective of this study: estimate prevalence of chronic pain in an ambulatory oncology population. Secondary objectives: describe pain, pain-related outcomes, and pain coping; differences (cancer pain vs. unrelated pain); correlations between scores.
Methods: Design: Cross sectional survey; Participants: Patients attending Northern Sydney Cancer Centre (Royal North Shore Hospital) who self-reported chronic pain gave verbal consent. Approved by NSLHD HREC. Funded by grant from North Foundation; Measures: Demographics; clinical information (cancer, pain); scores on Brief Pain Inventory (BPI), Depression Anxiety Stress Scale (DASS), Pain Self-Efficacy Questionnaire (PSEQ), Pain Catastrophizing Scale (PCS), using cut points based on norms for people with chronic non-cancer pain; pain-related distress, self-rated health. Sample size: Assuming 1500 patients attend NSCC, 50% have pain, 350 are needed for 95% CI of ± 5%.
Results. Of 350 patients surveyed during a 6-week period, only 70 (20%, 95% CI 16%-23%) reported chronic pain, and 60 provided data for analysis. Males were 39%, mean age 63±12 years. Nineteen patients had breast cancer, 6 prostate, 4 lung, 1 colorectal, while 40 had other primaries (5 with multiple primaries). 58% were having cancer treatment currently. Pain had been present for more than 5 years in 42%. The majority (36/60, 60%) attributed their pain to unrelated comorbidities, 18 to cancer treatment and 9 to cancer (3 reported more than one). 22% reported psychiatric comorbidity. Mean scores for pain intensity, pain interference, and pain related distress were moderate. Mean scores for depression, anxiety, and pain coping were mild. Nine patients (15%) had moderate-sever pain interference plus moderate-severe depressive symptoms. Poor pain coping (PCS and PSEQ scores) was highly correlated with pain interference and depression (both p<0.01), but not pain intensity.
Conclusion: Chronic pain was uncommon in the patients sampled, and when present was most commonly due to co-existing medical conditions. Poor pain outcomes (distress, depression, interference with function) were associated with unhelpful thoughts and beliefs about pain (high pain catastrophizing and low pain self-efficacy). They would be expected to benefit from working with a pain psychologist. Larger multicentre studies are needed to confirm these preliminary findings and evaluate psychosocial interventions.