Pain-related interference and pain-related distress of three different phenotypes of patients with chronic low back pain

Research Aim/Objective: To compare pain-related interference and pain-related distress among subgroups of chronic low back pain by their phenotypes, including localised low back pain, peripheral neuropathic back pain, andwidespread back pain. Secondarily, compare pain characteristics among the groups.
Research Methods: A cross-sectional study was conducted in 444 participants with chronic low back pain, recruited from outpatient physiotherapy clinics and community advertisements. Localised low back pain was identified when participants presented pain only in the low back region. Peripheral neuropathic back pain was classified based on the International Association for the Study of Pain classification. Widespread back pain was determined by the generalised pain criterion (pain in at least 4 of 5 regions in the Widespread Pain Index). Pain-related interference was investigated by Brief Pain Inventory and Patient-SpecificFunctional Scale. Pain-related distress assessment included psychosocial factors from Brief Screening Questions and maladaptive beliefs from Back Beliefs Questionnaire, self-efficacy, and expectation questions. Pain characteristics included pain intensity and pain duration. Ethical approval was granted.
Results: A one-way ANCOVA presented statistically significant differences among the groups. Participants with widespread back pain presented higher pain-related interference by Brief Pain Inventory [F(2,441) = 11.97, p<0.001], and pain-related distress regarding symptoms of anxiety [F(2,441) = 3.85, p=0.022], symptoms of depression [F(2,441) = 6.74, p=0.001], social isolation [F(2,441) = 6.54, p=0.002], catastrophising [F(2,441) = 9.72, p<0.001], perceived stress [F(2,441) = 3.93, p=0.020], maladaptive beliefs [F(2,441) = 6.89, p=0.001], and expectation [F(2,441) = 6.66, p=0.001] compared to localised low back pain group. Participants with peripheral neuropathic back pain and widespread back pain presented with similar phenotypes. Participants with localised low back pain reported a lower current pain intensity [F(2,441) = 6.77, p=0.001], and participants with widespread back pain presented a higher pain duration [F(2,425) = 9.83, p<0.001] compared to other groups.
Discussion: The broad implication of this research is that participants with different phenotypes present with different clinical and psychosocial outcomes. Participants with widespread back pain presented the highest pain-related interference, pain-related distress, pain intensity, and pain duration compared to the other phenotypes. Clinicians and researchers should consider the phenotype when addressing patients with chronic low back pain since they have different observable features that may require tailored treatment.