Nociceptive and neuropathic pain in patients with lung cancer: a comparison of pain quality descriptors.

Predictive validity of each word from the McGill Pain Questionnaire (MPQ) has not been investigated in relation to pain etiology. The purpose of this study was to explore differences in the words used to describe nociceptive and neuropathic pain. Patients with lung cancer (N = 123) selected words from the 78 MPQ pain quality descriptors and indicated the corresponding pain site for each word. Using only the MPQ pain location, and the cancer and treatment data abstracted from medical records, each pain site was classified as nociceptive or neuropathic (etiology). Pain etiology and quality descriptors were tested for proportional differences with sensitivity, specificity, and predictive value calculated for statistically significant descriptors. Of the 457 pain sites, 343 were classified as nociceptive (75%), 114 as neuropathic (25%). Lacerating, stinging, heavy, and suffocating were selected for a significantly larger proportion of nociceptive sites whereas throbbing, aching, numb, tender, punishing, pulling, tugging, pricking, penetrating, punishing, miserable, and nagging were selected for a larger proportion of neuropathic sites. Ten words correctly predicted 78% of the sites with 81% sensitivity to nociceptive pain and 59% sensitivity to neuropathic pain. Interestingly, several pain quality descriptors (burning, shooting, flashing, tingling, itching, and cold) previously associated with neuropathic pain did not distinguish between neuropathic and nociceptive pain. Infrequent selection of many MPQ words and lack of neurological exam data in the medical records are possible explanations for inconsistency with previous literature. Prospective studies are needed to validate pain quality descriptors for nociceptive and neuropathic types of lung cancer pain.