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ObjectivesThe relationship of pain sensitivity with pain and disability in low back pain (LBP) is complicated. It has been suggested increased understanding of dynamic quantitative sensory testing (QST) might be useful in increasing understanding of these relationships. This study aimed to create subgroups based on participant responses to dynamic QST, profile these subgroups based on multidimensional variables (including clinical measures of pain and disability, psychological and lifestyle variables and static QST), and investigate the association of subgroup membership with levels of pain intensity, LBP-related disability and disability risk at 12-month follow up.MethodsParticipants (n=273) with dominant axial chronic non-specific LBP with duration of pain >3 months were included in this study. At baseline, eligible participants completed a self-report questionnaire to collect demographic, clinical, psychological and lifestyle data prior to dynamic and static QST. Dynamic QST measures were conditioned pain modulation (CPM) and temporal summation (TS). At 12-months follow up, clinical data were collected, including pain intensity and LBP-related disability. Sub-groups were formed by cross-tabulation. Analysis was undertaken to profile dynamic QST subgroup on demographic, clinical, psychological, lifestyle and static QST measures. Associations between dynamic QST subgroups and follow-up clinical variables were examined.ResultsBased on dynamic QST, participants were allocated into four subgroups; normal CPM and normal TS (n=34, 12.5%); normal CPM and facilitated TS (n=6, 2.2%); impaired CPM and normal TS (n=186, 68.1%); impaired CPM and facilitated TS (n=47, 17.2%). At baseline no differences were demonstrated between subgroups across most clinical variables, or any psychological or lifestyle measures. The two subgroups with impaired CPM were more likely to have a higher number of painful body areas. Cold pain sensitivity was heightened in both the subgroups with facilitated TS. Subgroups did not differ across pain intensity, LBP-related disability and disability risk stratification at follow-up.ConclusionsThe profiles of people with axial LBP did not vary significantly across dynamic QST subgroups, save for those in groups with impaired CPM being more likely to have more widespread symptoms and those with facilitated TS having heightened cold pain sensitivity. Further, subgroup membership was not related to future pain and disability. The role of dynamic QST profiles in LBP remains unclear. Further work is required to understand the role of pain sensitivity in LBP. The utility of dynamic QST subgrouping might not be in determining of future disability. Future research might focus on treatment modifying effects of dynamic QST subgroups.

Background Improvement in cardiac function has been demonstrated after thyroxine treatment in humans with hypothyroidism using the myocardial performance index (MPI). Cardiac changes after thyroxine supplementation are poorly documented in dogs with spontaneous hypothyroidism and comparison with clinically healthy dogs is lacking. Objectives To evaluate the electrical activity and mechanical function of the heart in dogs with primary hypothyroidism at baseline (T0) and after thyroxine supplementation (T60). Animals Forty client‐owned dogs with hypothyroidism and 20 clinically healthy dogs. Methods Prospective cohort study. Selected electrocardiographic and echocardiographic variables, including the MPI, were measured in all dogs at T0 and in 30 hypothyroid dogs at T60. Results Hypothyroid dogs had significantly decreased median or mean heart rate (HR), P wave amplitude, and R wave amplitude (P = .04, P = .002, and P = .003, respectively) and E‐point‐to‐septal separation normalized to body weight (EPSSn) and trans‐mitral E wave velocity (E max; P