Clinical phenotypes in patients with knee osteoarthritis: a study in the Amsterdam osteoarthritis cohort

OBJECTIVE

To identify and validate previously established phenotypes of knee osteoarthritis (OA) based on similarities in clinical patient characteristics.

METHODS

Knee OA patients (N = 551) from the Amsterdam OA (AMS-OA) cohort provided data. Four clinical patient characteristics were assessed: upper leg muscle strength, body mass index (BMI), radiographic severity (Kellgren/Lawrence [KL] grade), and depressive mood (the Hospital Anxiety and Depression Scale [HADS] questionnaire). Cluster analysis was performed to identify the optimal number of phenotypes. Differences in clinical characteristics between the phenotypes were analyzed with ANOVA.

RESULTS

Cluster analysis identified five phenotypes of knee OA patients: "minimal joint disease phenotype", "strong muscle strength phenotype", "severe radiographic OA phenotype", "obese phenotype", and "depressive mood phenotype".

CONCLUSIONS

Among patients with knee OA, five phenotypes were identified based on four clinical characteristics. To a high degree, the results are a replication of earlier findings in the OA Initiative, indicating that these five phenotypes seem a stable, valid, and clinically relevant finding.

Improvement in upper leg muscle strength underlies beneficial effects of exercise therapy in knee osteoarthritis: secondary analysis from a randomised controlled trial

OBJECTIVES

Although exercise therapy is effective for reducing pain and activity limitations in patients with knee osteoarthritis (OA), the underlying mechanisms are unclear. This study aimed to evaluate if improvements in neuromuscular factors (i.e. upper leg muscle strength and knee proprioception) underlie the beneficial effects of exercise therapy in patients with knee OA.

DESIGN

Secondary analyses from a randomised controlled trial, with measurements at baseline, 6 weeks, 12 weeks and 38 weeks.

SETTING

Rehabilitation centre.

PARTICIPANTS

One hundred and fifty-nine patients diagnosed with knee OA.

INTERVENTION

Exercise therapy.

MAIN OUTCOME MEASURES

Changes in pain [numeric rating scale (NRS)] and activity limitations [Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) physical function subscale and get-up-and-go test] during the study period. Independent variables were changes in upper leg muscle strength and knee joint proprioception (i.e. motion sense) during the study period. Longitudinal regression analyses (generalised estimating equation) were performed to analyse associations between changes in upper leg muscle strength and knee proprioception with changes in pain and activity limitations.

RESULTS

Improved muscle strength was significantly associated with reductions in NRS pain {B coefficient -2.5 [95% confidence interval (CI) -3.7 to -1.4], meaning that every change of 1 unit of strength was linked to a change of -2.5 units of pain}, WOMAC physical function (-8.8, 95% CI -13.4 to -4.2) and get-up-and-go test (-1.7, 95% CI -2.4 to -1.0). Improved proprioception was not significantly associated with better outcomes of exercise therapy (P>0.05).

CONCLUSIONS

Upper leg muscle strengthening is one of the mechanisms underlying the beneficial effects of exercise therapy in patients with knee OA.

Study description and baseline characteristics of the population enrolled in a multinational observational study of extended teriparatide use (ExFOS)

OBJECTIVE

To better characterize patients who are currently being prescribed teriparatide in Europe, this article describes the study design and baseline characteristics of participants of the Extended Forsteo * Observational Study (ExFOS).

RESEARCH DESIGN AND METHODS

ExFOS is a noninterventional, multicenter, prospective, observational study in men and women with osteoporosis treated with teriparatide during the course of normal clinical practice for up to 24 months and with a post-treatment follow-up of at least 18 months.

MAIN OUTCOME MEASURES

Baseline characteristics, including history of fracture and back pain, and health-related quality of life (HRQoL, assessed using the EuroQol-5 Dimension [EQ-5D]).

RESULTS

Of 1607 patients enrolled, 90.9% were women. At baseline, mean (standard deviation [SD]) age was 70.3 (9.8) years, and 85.8% of patients had a history of fracture (64.7% with ≥2 fragility fractures). Of those with historic fractures, 90.8% had vertebral fractures (67.8% had thoracic fractures). The mean (SD) of reported bone mineral density T-scores were -3.0 (1.2), -2.4 (1.0), and -2.5 (0.9) for lumbar spine, total hip (left), and femoral neck (left), respectively. Overall, 39.3% of patients had experienced ≥1 fall during the 12 months before enrollment. At baseline, 11.4% of patients were osteoporosis-treatment naïve and 15% were currently using glucocorticoids. The mean (SD) visual analog scale score for back pain during the last month was 50.7 (26.9), and 62.1% of patients experienced daily or almost daily back pain. The median EQ-5D health state value at baseline was 0.62 (first and third quartiles: 0.19, 0.74).

CONCLUSIONS

Baseline characteristics of the ExFOS study cohort indicate that patients prescribed teriparatide in Europe have severe osteoporosis with highly prevalent vertebral fractures, frequent and disabling back pain, and a poor HRQoL, despite previous pharmacotherapy for osteoporosis. Limitations include non-randomization, lack of a comparator group, and patient self-report for data on prior medication and fracture history.

Serotonergic reinforcement of intestinal barrier function is impaired in irritable bowel syndrome

BACKGROUND

Alterations in serotonergic (5-HT) metabolism and/or intestinal integrity have been associated with irritable bowel syndrome (IBS).

AIMS

To assess the effects of the precursor of 5-HT, 5-hydroxytryptophan (5-HTP), on mucosal 5-HT availability and intestinal integrity, and to assess potential differences between healthy controls and IBS patients.

METHODS

Fifteen IBS patients and 15 healthy volunteers participated in this randomised double-blind placebo-controlled study. Intestinal integrity was assessed by dual-sugar test and by determining the mucosal expression of tight junction proteins after ingestion of an oral bolus of 100 mg 5-HTP or placebo. Mucosal serotonergic metabolism was assessed in duodenal biopsy samples.

RESULTS

5-HTP administration significantly increased mucosal levels of 5-HIAA, the main metabolite of 5-HT, in both healthy controls (7.1 ± 1.7 vs. 2.5 ± 0.7 pmol/mg, 5-HTP vs. placebo, P = 0.02) and IBS patients (20.0 ± 4.8 vs. 8.1 ± 1.3 pmol/mg, 5-HTP vs. placebo, P = 0.02), with the latter group showing a significantly larger increase. Lactulose/L-rhamnose ratios were significantly lower after administration of 5-HTP (P < 0.05) in healthy controls and were accompanied by redistribution of zonula occludens-1 (ZO-1), pointing to reinforcement of the barrier. In IBS, expression of the tight junction proteins was significantly lower compared to healthy controls, and 5-HTP resulted in a further decrease in occludin expression.

CONCLUSIONS

Oral 5-HTP induced alterations in mucosal 5-HT metabolism. In healthy controls, a reinforcement of the intestinal barrier was seen whereas such reaction was absent in IBS patients. This could indicate the presence of a serotonin-mediated mechanism aimed to reinforce intestinal barrier function, which seems to dysfunction in IBS patients.

REG3γ-deficient mice have altered mucus distribution and increased mucosal inflammatory responses to the microbiota and enteric pathogens in the ileum

REG3γ is considered to have a protective role against infection with Gram-positive bacteria due to its bactericidal activity, but evidence from in vivo studies is lacking. We generated a REG3γ(-/-) mouse, and investigated the effect of lack of REG3γ on intestinal mucus distribution, spatial compartmentalization of bacteria, and expression of innate immunity genes. Infection studies were also performed with Gram-positive and Gram-negative pathogens to investigate the antimicrobial role of REG3γ. REG3γ(-/-) mice display altered mucus distribution, increased bacterial contact with the epithelium, and elevated inflammatory markers in the ileum without histological evidence of pathology. Infection response pathway genes were differentially expressed in both Listeria monocytogenes and Salmonella enteritidis infected REG3γ(-/-) and wild-type (wt) mice. Higher amounts of myeloperoxidase and interleukin-22 transcripts were present in the ileal mucosa of REG3γ(-/-) than wt mice, but translocation to the organs was unaffected. We concluded that REG3γ has a protective role against mucosal infection with pathogenic Listeria and Salmonella in vivo. REG3γ is equally distributed throughout the mucus and its absence results in increased epithelial contact with the microbiota resulting in low-grade inflammation. REG3γ can bind to Gram-negative and Gram-positive bacteria and influence mucus distribution in the ileum, properties which may contribute to mucosal protection.