Muscle Deficits in Rheumatoid Arthritis Contribute to Inferior Cortical Bone Structure and Trabecular Bone Mineral Density

Skeletal muscle index together with body mass index is associated with secondary osteoporosis in patients with rheumatoid arthritis

OBJECTIVE

The objective of this study was to explore the associations of body mass index (BMI), fat mass index (FMI), skeletal mass index (SMI) and secondary osteoporosis (OP) in patients with rheumatoid arthritis (RA).

METHODS

The bone mineral density (BMD) at sites of the femur neck (Neck), total hip (Hip) and lumbar vertebrae 1-4 (L1-4) was measured by dual-energy X-ray absorptiometry. The skeletal muscle index, body fat percentage and mineral content were measured by biological electrical impedance for calculating BMI, FMI and SMI.

RESULTS

A total of 433 patient with RA and 158 healthy controls were enrolled. The BMDs at each site of the RA patients were lower compared with those of the healthy controls (p < 0.0001), and the prevalence of OP (36.1%, 160/443) and sarcopenia (65.2%, 288/443) in the RA patients were higher than those in the controls (12.7%, 20/158, p < 0.0001; 9.0%, 14/156, p < 0.0001). Significant differences in the BMD, FMI, SMI, mineral content, body fat percentage and skeletal muscle mass were found among the RA patients in the different BMI groups (p < 0.05). In RA patients with BMI < 18.5 kg/m2, the prevalence of OP in the RA patients with sarcopenia was similar to that in those without sarcopenia (44.4% vs. 66. 7%, χ2 = 0. 574, p = 0.449). In the RA patients with a normal BMI or who were overweight or obese, prevalence of OP in the RA patients with sarcopenia was significantly higher than that in the RA patients without sarcopenia (42.8% vs. 21.7%, χ2 = 10.951, p = 0.001; 61.1% vs. 13.0%, χ2 = 26.270, p < 0.0001). In the RA patients without sarcopenia, the prevalence of OP in the RA patients in the different BMI groups was different (p = 0.039). In the RA patients with sarcopenia, there was no significant difference in the prevalence of OP among the RA patients in the different BMI groups (p = 0. 128). The linear correlation analysis showed that the SMI in RA patients was positively correlated with the BMD of each site measured and BMI and FMI (p < 0.0001). However, there was a negative linear correlation between SMI and disease duration (p = 0.048). The logistic regression analysis found that SMI (OR = 0.569, p = 0.002, 95% CI 0.399-0.810), BMI (OR = 0.884, p = 0.01, 95% CI 0.805-0.971) and gender (1 = female, 2 = male) (OR = 0.097, p < 0.0001, 95% CI 0.040-0.236) were protective factors for OP in RA, while age (OR = 1.098, p < 0.0001, 95% CI 1.071-1.125) was the risk factor.

CONCLUSION

BMI and SMI are associated with the occurrence of OP in RA patients, and both SMI and BMI are important protective factors for OP secondary to RA.

The assessment value of pathological condition of serum adiponectin and amylin in primary osteoporosis and its correlation analysis with bone metabolism indexes

Background

This paper explores the assessment value of pathological condition of serum adiponectin (APN) and amylin in primary osteoporosis (POP) and their correlation with bone metabolism indexes.

Methods

From January 2019 to June 2021, 79 cases of POP patients were selected as the research objects. A test of the patients' bone density was conducted, and clinical grading of POP was via T value (normal, mild, moderate, severe). The analysis of the assessment value of pathological condition of serum APN and amylin for POP and their association with bone metabolism indexes in patients was performed.

Results

APN and amylin in patients were declined with POP's aggravation. APN of 5.15 μg/mL or less and amylin of 15.38 pmol/L or less were risk factors influencing the aggravation of pathological condition of POP (P< 0 .0 5). The area under the curve (AUC) of combined detection of APN and amylin to assess the severity of POP was elevated vs. alone test of amylin (P< 0.05). 25-hydroxyvitamin D (25-(OH) D) and total type 1 procollagen amino-terminal propeptide (t-PINP) in patients were descended with the aggravation of pathological condition of osteoporosis (P < 0.05). At the same time, no distinct differences were presented in the three groups of type I collagen hydroxyl terminal peptide b degradation product (β-CTX) and N-terminal osteocalcin (N-MID) (P> 0.05). APN, amylin, 25-(OH)D, β-CTX, and t-PINP were negatively linked with POP clinical grade (P< 0.05). APN and amylin were associated with 25-(OH) D, β-CTX, t-PINP (P< 0.05), and APN and amylin were not linked with N-MID (P> 0.05).

Conclusions

Serum APN and amylin are provided with evaluation values for the severity of POP and are associated with bone metabolism in patients.

Osteoporosis and fractures in rheumatoid arthritis - risk factors

In this chapter, we emphasize among rheumatoid arthritis (RA) patients, whom and how to screen for osteoporosis. We highlight certain modalities, advancements in technology, secondary osteoporosis workup, and laboratory testing as well as their caveats. Finally, we discuss current guidance on how to direct the laboratory and radiology testing in the context of the individual patient with RA to guide and select from the osteoporosis treatment options currently available.

Risk factors for osteoporosis and fractures in rheumatoid arthritis

People with rheumatoid arthritis (RA) have both disease-specific risk factors for osteoporosis and fractures in addition to those that affect the general population. Disease specific risks include directly pathogenic auto-antibodies, chronic exposure to systemic inflammation, and joint damage causing early disability. Risk factors that affect the general population which may have a higher prevalence in RA include smoking, calcium and vitamin D deficiency as well as hypogonadism. Additionally, chronic exposure to glucocorticoids results in reduced bone mineral density and body composition changes which can further increase fracture risk. In this review we discuss these risk-factors for osteoporosis as well as factors that may impact fall and fracture risk in people with RA.

Morphological Parameters in Quadriceps Muscle Were Associated with Clinical Features and Muscle Strength of Women with Rheumatoid Arthritis: A Cross-Sectional Study

Background: Rheumatoid arthritis (RA) is an autoimmune, inflammatory and chronic disease that may lead to loss of muscle mass, muscle strength and decreased functionality. Our objectives are to assess the quadriceps muscle morphology by ultrasound (MU) and verify its associations with clinical features, muscle strength and physical function in RA patients. Methods: In this cross-sectional study, RA women (≥18 years) were included. Morphological parameters in quadriceps muscle consisted of the muscle thickness and pennation angle of rectus femoris (RF), vastus intermedius (VI) and vastus lateralis (VL). RA activity was measured by a 28-joint disease activity score (DAS28), muscle strength by handgrip and chair stand tests, and physical function by health assessment questionnaire (HAQ), timed-up-and-go (TUG) test and short physical performance battery (SPPB). Results: Fifty-five patients were included (age: 56.73 ± 9.46 years; DAS28: 3.08 ± 1.29). Muscle thickness in RF, VI and VL were negatively associated with age (RF, p < 0.001; VI, p = 0.013; VL, p = 0.002) and disease duration (RF, p < 0.001; VI, p = 0.005; VL, p = 0.001), and were positively associated with handgrip strength (RF, p = 0.015; VI, p = 0.022; VL, p = 0.013). In addition, decreased muscle thickness in VI (p = 0.035) and a smaller pennation angle in RF (p = 0.030) were associated with higher DAS-28 scores. Conclusion: Quadriceps muscle morphology by ultrasound appears to be affected by age, disease duration, disease activity and muscle strength in patients with RA. MU can be a useful method to evaluate the impact of the disease on skeletal muscle.

Peripheral Volumetric Muscle Area and Total Body Volume in Postmenopausal Women With Rheumatoid Arthritis

The effect of rheumatoid arthritis (RA) on peripheral muscle parameters is not completely understood. This study aimed to elucidate the influence of RA on peripheral muscle area and whole body skeletal muscle mass index (SMI) using peripheral quantitative computed tomography and dual-energy X-ray absorptiometry in postmenopausal women. This cross-sectional study included 54 postmenopausal women with RA and 86 healthy controls. Peripheral quantitative computed tomography and dual-energy X-ray absorptiometry were used to measure the muscle cross-sectional area and skeletal muscle mass. Muscle strength was assessed using a handheld dynamometer. Additionally, the effects of RA on muscle area and density as well as the bone / muscle area ratio were analyzed using multivariate models. The muscle area index of the thigh and forearm were correlated between both groups (RA: r = 0.357, p = 0.030; and healthy controls: r = 0.608, p < 0.001) and each index correlated with SMI in RA and healthy controls (p < 0.001). Bone / muscle area ratio correlated between forearms and thighs in health controls only (r = 0.547, p < 0.001). The RA group had a decreased thigh muscle area (p = 0.014); the fat area and fat muscle area ratio at the thigh and forearm were significantly increased (all p < 0.001), as well as thigh bone / muscle area ratio (p = 0.015). The RA group also had significantly lower forearm muscle density (p < 0.001). A sensitivity analysis excluding those on bisphosphonates led to similar results. Independent of RA, the thigh and forearm muscle area correlate with each other and with SMI. Differences in the bone / muscle ratio between RA and healthy controls may indicate regional muscle effects of inflammation and inactivity.

Osteoporosis and fractures in rheumatoid arthritis

PURPOSE OF REVIEW

Rheumatoid arthritis (RA) is associated with increased risk for osteoporotic fracture. We highlight RA-specific risk factors for bone mineral density (BMD) loss and fractures and considerations regarding the diagnosis and treatment of osteoporosis in patients with RA.

RECENT FINDINGS

Anticitrullinated protein antibody (ACPA) positivity, although associated with low BMD in early RA, is not associated with accelerated BMD loss over time when compared to ACPA negative individuals. Studies have found reduced BMD in individuals on low doses of glucocorticoids (GCs). Poor functional status and frailty are additional important risk factors for low BMD and fractures. Heightened fracture risk in RA may be mitigated by tight disease control, and biologic therapies are associated with more stable BMD compared to nonbiologic therapies. Evidence-based guidelines specific for treating osteoporosis in patients with RA do not exist. Thus, treatment decisions are based on general osteoporosis guidelines, taking into account additional RA-specific risk factors.

SUMMARY

Recent studies have advanced knowledge of RA-specific risk factors for BMD loss and fractures. Future studies applying these findings to modify established fracture risk algorithms as well as evaluating osteoporosis treatments in RA cohorts are needed to reduce the risk of disabling fractures in these patients.

Adiponectin Deregulation in Systemic Autoimmune Rheumatic Diseases

Deregulation of adiponectin is found in systemic autoimmune rheumatic diseases (SARDs). Its expression is downregulated by various inflammatory mediators, but paradoxically, elevated serum levels are present in SARDs with high inflammatory components, such as rheumatoid arthritis and systemic lupus erythematosus. Circulating adiponectin is positively associated with radiographic progression in rheumatoid arthritis as well as with cardiovascular risks and lupus nephritis in systemic lupus erythematosus. However, in SARDs with less prominent inflammation, such as systemic sclerosis, adiponectin levels are low and correlate negatively with disease activity. Regulators of adiponectin gene expression (PPAR-γ, Id3, ATF3, and SIRT1) and inflammatory cytokines (interleukin 6 and tumor necrosis factor α) are differentially expressed in SARDs and could therefore influence total adiponectin levels. In addition, anti-inflammatory therapy could also have an impact, as tocilizumab treatment is associated with increased serum adiponectin. However, anti-tumor necrosis factor α treatment does not seem to affect its levels. Our review provides an overview of studies on adiponectin levels in the bloodstream and other biological samples from SARD patients and presents some possible explanations why adiponectin is deregulated in the context of therapy and gene regulation.

Association of Low Muscle Density With Deteriorations in Muscle Strength and Physical Functioning in Rheumatoid Arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is associated with low muscle density due to the accumulation of intramuscular fat. The present study was undertaken to identify predictors of changes in muscle density and to determine whether low muscle density predicted changes in strength and physical function.

METHODS

Patients with RA, ages 18-70 years, completed whole-body dual-energy x-ray absorptiometry and peripheral quantitative computed tomography to quantify lean and fat mass indices and muscle density. Dynamometry was used to measure strength at the hand, knee, and lower leg. Disability and physical function were measured with the Health Assessment Questionnaire (HAQ) and the Short Physical Performance Battery (SPPB). Assessments were performed at baseline and at follow-up. Regression analyses assessed associations between patient characteristics, muscle density, and deteriorations in strength and function.

RESULTS

Muscle density was assessed at baseline in 107 patients with RA. Seventy-nine of these patients (74%) returned for a follow-up assessment at a median follow-up time of 2.71 years (interquartile range 2.35-3.57). Factors associated with declines in muscle density included female sex, higher disease activity, smoking, and lower insulin-like growth factor 1 (IGF-1) levels. Greater muscle density Z score at baseline (per 1 SD) was associated with less worsening per year according to HAQ, SPPB, and 4-meter walk time scores and a lower risk of a clinically important worsening in HAQ score (odds ratio [OR] 1.90 [95% confidence interval (95% CI) 1.06, 3.42]; P = 0.03) and walking speed (OR 2.87 [95% CI 1.05, 7.89]; P = 0.04).

CONCLUSION

Worsening of skeletal muscle density occurred in patients with higher disease activity, in smokers, and in those with lower IGF-1. Low muscle density was associated with worsening of physical function. Interventions addressing reductions in muscle quality might prevent functional decline.

Studying bone mineral density in young people: The complexity of choosing a pQCT reference database

BACKGROUND

Many chronic illnesses affect bone health, and commonly lead to mineralization abnormalities in young people. As cortical and trabecular bone may be differentially affected in certain diseases, an imaging technique that allows for detailed study of the bone structure is required. Peripheral quantitative computed tomography (pQCT) overcomes the limitations of dual energy X-ray absorptiometry (DXA) and is perhaps more widely available for use in research than bone biopsy. However, in contrast to DXA, where there are large reference datasets, this is not the case for pQCT.

METHODS

Fifty-five children and young adults aged 7 to 30 years had the non-dominant tibia scanned at the 3% & 4% sites for trabecular bone mineral density and the 38% site for cortical bone mineral density and bone mineral content. Image acquisition and analysis was undertaken according to the protocols of two of the largest reference datasets for tibial pQCT. The Z-scores generated were compared to examine the differences between protocols and the differences from the expected median of zero in a healthy population.

RESULTS

The trabecular bone mineral density Z-scores generated by the two protocols were similar. The same was true for cortical mineral content Z-scores at the 38% site. Cortical bone mineral density was significantly different between protocols and likely affected by differences in the ethnicity of our cohort compared to the reference datasets. Only one reference dataset extended from childhood to young adulthood. Only trabecular bone mineral density, periosteal and endosteal circumference Z-scores from one methodology were not significantly biased when tested for deviation of the median from zero.

CONCLUSIONS

pQCT is a useful tool for studying trabecular and cortical compartments separately but, there are variations in pQCT scanning protocols, analysis methodology, and a paucity of reference data. Reference datasets may not be generalizable to local study populations, even when analysed using identical analysis protocols.

Drugs Causing Bone Loss

Drugs may cause bone loss by lowering sex steroid levels (e.g., aromatase inhibitors in breast cancer, GnRH agonists in prostate cancer, or depot medroxyprogestone acetate - DMPA), interfere with vitamin D levels (liver inducing anti-epileptic drugs), or directly by toxic effects on bone cells (chemotherapy, phenytoin, or thiazolidinedions, which diverts mesenchymal stem cells from forming osteoblasts to forming adipocytes). However, besides effects on the mineralized matrix, interactions with collagen and other parts of the unmineralized matrix may decrease bone biomechanical competence in a manner that may not correlate with bone mineral density (BMD) measured by dual energy absorptiometry (DXA).Some drugs and drug classes may decrease BMD like the thiazolidinediones and consequently increase fracture risk. Other drugs such as glucocorticoids may decrease BMD, and thus increase fracture risk. However, glucocorticoids may also interfere with the unmineralized matrix leading to an increase in fracture risk, not mirrored in BMD changes. Some drugs such as selective serotonin reuptake inhibitors (SSRI), paracetamol, and non-steroidal anti-inflammatory drugs (NSAIDs) may not per se be associated with bone loss, but fracture risk may be increased, possibly stemming from an increased risk of falls stemming from effects on postural balance mediated by effects on the central nervous system or cardiovascular system.This paper performs a systematic review of drugs inducing bone loss or associated with fracture risk. The chapter is organized by the Anatomical Therapeutic Chemical (ATC) classification.

Intramuscular Fat Accumulation and Associations With Body Composition, Strength, and Physical Functioning in Patients With Rheumatoid Arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is associated with adverse body composition profiles and low muscle density due to the accumulation of intramuscular fat. Linear regression was used to assess differences between RA patients and controls and to determine associations between muscle density, strength, and physical functioning.

METHODS

Patients with RA, ages 18-70 years, and healthy control subjects underwent whole-body dual x-ray absorptiometry and peripheral quantitative computed tomography, in order to quantify the appendicular lean mass index (ALMI) and the fat mass index (FMI), visceral fat area, and muscle density. Dynamometry was used to measure hand grip strength and muscle strength at the knee and lower leg. Disability and physical functioning were measured using the Health Assessment Questionnaire (HAQ) and the Short Physical Performance Battery (SPPB). Linear regression analyses were performed to assess differences related to RA and associations between muscle density, strength, and function.

RESULTS

The study group included 103 patients with RA (51 men) and 428 healthy control subjects. Among patients with RA, low muscle density was associated with higher disease activity, C-reactive protein and interleukin-6 levels, greater total and visceral fat area, lower ALMI Z scores, physical inactivity, and long-term use of glucocorticoids (>1 year). Patients with low ALMI Z scores had lower muscle density Z scores compared with reference participants with similarly low ALMI scores. Low muscle density was independently associated with lower muscle strength, higher HAQ scores, and lower SPPB scores, after adjustment for ALMI and FMI Z scores.

CONCLUSION

The low muscle density observed in patients with RA was associated with low muscle mass, excess adiposity, poor strength, and greater disability. Interventions to address poor muscle quality could potentially affect important functional outcomes.