Meta-analysis is a method to obtain a weighted average of results from various studies. In addition to pooling effect sizes, meta-analysis can also be used to estimate disease frequencies, such as incidence and prevalence. In this article we present methods for the meta-analysis of prevalence. We discuss the logit and double arcsine transformations to stabilise the variance. We note the special situation of multiple category prevalence, and propose solutions to the problems that arise. We describe the implementation of these methods in the MetaXL software, and present a simulation study and the example of multiple sclerosis from the Global Burden of Disease 2010 project. We conclude that the double arcsine transformation is preferred over the logit, and that the MetaXL implementation of multiple category prevalence is an improvement in the methodology of the meta-analysis of prevalence.

Meta-analysis of prevalence

Nociplastic pain: towards an understanding of prevalent pain conditions

Musculoskeletal conditions include more than 150 diagnoses that affect the locomotor system. These conditions are characterized by pain and reduced physical function, often leading to significant mental health decline, increased risk of developing other chronic health conditions and increased all-cause mortality.1 Many musculoskeletal conditions share risk factors common to other chronic health conditions, such as obesity, poor nutrition and a sedentary lifestyle. Musculoskeletal conditions account for the greatest proportion of persistent pain across geographies and ages.2 Back and neck pain, osteoarthritis, rheumatoid arthritis and fractures are among the most disabling musculoskeletal conditions and pose major threats to healthy ageing by limiting physical and mental capacities and functional ability. Although the prevalence of major musculoskeletal conditions increases with age, they are not just conditions of older age. Regional pain conditions, low back and neck pain, musculoskeletal injury sequelae and inflammatory arthritides commonly affect children, adolescents and middle-aged people during their formative and peak income-earning years, establishing trajectories of decline in intrinsic capacity in later years. While point prevalence estimates vary with respect to age and musculoskeletal condition, approximately one in three people worldwide live with a chronic, painful musculoskeletal condition. Notably, recent data suggest that one in two adult Americans live with a musculoskeletal condition, a prevalence comparable to that of cardiovascular and chronic respiratory diseases combined, which cost 213 billion United States dollars in 2011 (or 1.4% of gross domestic product).3 Data from lowand middle-income countries are fewer, yet comparable.4 Musculoskeletal health is critical for human function, enabling mobility, dexterity and the ability to work and actively participate in all aspects of life. Musculoskeletal health is therefore essential for maintaining economic, social and functional independence, as well as human capital across the life course. Impaired musculoskeletal health is responsible for the greatest loss of productive life years in the workforce compared with other noncommunicable diseases,5 commonly resulting in early retirement and reduced financial security. In subsistence communities and lowand middle-income economies, impaired musculoskeletal health has profound consequences on an individual’s ability to participate in social roles and in the prosperity of communities.4

Reducing the global burden of musculoskeletal conditions.

To summarize the current understanding of the global burden of musculoskeletal pain-related conditions, consider the process of evidence generation and the steps to generate global pain estimates, identify key gaps in our understanding, and propose an agenda to address these gaps, we performed a narrative review. In the 2010 Global Burden of Disease Study (GBD), which broadened the scope of musculoskeletal conditions that were included over previous rounds, low back pain imposed the highest disability burden of all specific conditions assessed, and subsequent GBD reports further reinforce the size of this burden. Over the past decade, the GBD has produced compelling evidence of the leading contribution of musculoskeletal pain conditions to the global burden of disability, but this has not translated into global health policy initiatives. However, system- and service-level responses to the disease burden persist across high-, middle-, and low-income settings. There is a mismatch between the burden of musculoskeletal pain conditions and appropriate health policy response and planning internationally that can be addressed with an integrated research and policy agenda.

The Global Burden of Musculoskeletal Pain-Where to From Here?

This review discusses the interplay between multimorbidity (i.e. co-occurrence of more than one chronic health condition in an individual) and functional impairment (i.e. limitations in mobility, strength or cognition that may eventually hamper a person's ability to perform everyday tasks). On the one hand, diseases belonging to common patterns of multimorbidity may interact, curtailing compensatory mechanisms and resulting in physical and cognitive decline. On the other hand, physical and cognitive impairment impact the severity and burden of multimorbidity, contributing to the establishment of a vicious circle. The circle may be further exacerbated by people's reduced ability to cope with treatment and care burden and physicians' fragmented view of health problems, which cause suboptimal use of health services and reduced quality of life and survival. Thus, the synergistic effects of medical diagnoses and functional status in adults, particularly older adults, emerge as central to assessing their health and care needs. Furthermore, common pathways seem to underlie multimorbidity, functional impairment and their interplay. For example, older age, obesity, involuntary weight loss and sedentarism can accelerate damage accumulation in organs and physiological systems by fostering inflammatory status. Inappropriate use or overuse of specific medications and drug-drug and drug-disease interactions also contribute to the bidirectional association between multimorbidity and functional impairment. Additionally, psychosocial factors such as low socioeconomic status and the direct or indirect effects of negative life events, weak social networks and an external locus of control may underlie the complex interactions between multimorbidity, functional decline and negative outcomes. Identifying modifiable risk factors and pathways common to multimorbidity and functional impairment could aid in the design of interventions to delay, prevent or alleviate age-related health deterioration; this review provides an overview of knowledge gaps and future directions.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/joim.12843

Multimorbidity and functional impairment-bidirectional interplay, synergistic effects and common pathways

People frequently live for many years with multiple chronic conditions (multimorbidity) that impair health outcomes and are expensive to manage. Multimorbidity has been shown to reduce quality of life and increase mortality. People with multimorbidity also rely more heavily on health and care services and have poorer work outcomes. Musculoskeletal disorders (MSDs) are ubiquitous in multimorbidity because of their high prevalence, shared risk factors, and shared pathogenic processes amongst other long-term conditions. Additionally, these conditions significantly contribute to the total impact of multimorbidity, having been shown to reduce quality of life, increase work disability, and increase treatment burden and healthcare costs. For people living with multimorbidity, MSDs could impair the ability to cope and maintain health and independence, leading to precipitous physical and social decline. Recognition, by health professionals, policymakers, non-profit organisations, and research funders, of the impact of musculoskeletal health in multimorbidity is essential when planning support for people living with multimorbidity.

The contribution of musculoskeletal disorders in multimorbidity: Implications for practice and policy.

Depression is common among patients with axial spondyloarthritis (axSpA), but reports of its prevalence are highly variable. We performed a systematic review to (i) describe the prevalence of depression in axSpA, (ii) compare its prevalence between axSpA, ankylosing spondylitis (AS) and non-radiographic axSpA (nr-axSpA) cohorts, and (iii) compare disease activity and functional impairment between those with and without depression. We searched Medline, PubMed, Web of Science, PsycINFO, CINAHL Plus, the Cochrane library and conference abstracts of the European League Against Rheumatism, British Society for Rheumatology and American College of Rheumatology using a predefined protocol in accordance with Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Meta-analysis was performed using quality-effects model. Fifteen original articles and one abstract were included for analysis; 14 studies described AS cohorts and two nr-axSpA. Three screening criteria and one diagnostic criterion were used to define depression. Prevalence ranged from 11 to 64% depending on criteria and thresholds used. Pooled prevalence of at least moderate depression was 15% using the Hospital Anxiety and Depression Scale (HADS) threshold of ≥ 11. The prevalence of depression was similar between axSpA, AS and nr-axSpA cohorts. Patients with depression had significantly worse disease activity, including higher BASDAI by 1.4 units (95% CI 1.0 to 1.9), ASDAS by 0.5 units (95% CI 0.3 to 0.7) and ESR by 3.5 mm/h (95% CI 0.6 to 6.4). They also had greater functional impairment with higher BASFI and BASMI by 1.2 units (95% CI 0.6 to 1.8) and 0.6 units (95% CI 0.3 to 0.8), respectively. Mean age of each study cohort inversely correlated with depression prevalence. Depression is common among axSpA patients and is associated with more severe disease activity and functional impairment. Identifying and managing depression should form part of their holistic care. Further longitudinal studies are needed to explore the impact of depression on treatment outcomes and axSpA treatment on symptoms of depression.

/pdf/the-prevalence-of-depression-in-axial-spondyloarthritis-and-34hzd38zki.pdf

The prevalence of depression in axial spondyloarthritis and its association with disease activity: a systematic review and meta-analysis

Objectives This systematic review and meta-analysis will describe the prevalence of concomitant FM in adults with inflammatory arthritis and quantify the impact of FM on DAS. Methods Cochrane library, MEDLINE, Psychinfo, PubMed, Scopus and Web of Science were searched using key terms and predefined exclusion criteria. As appropriate, proportional and pairwise meta-analysis methods were used to pool results. Results Forty articles were identified. In RA the prevalence of FM ranged from 4.9 to 52.4% (21% pooled). In axSpA the range was 4.11-25.2% (13% pooled in AS only). In PsA the range was 9.6-27.2% (18% pooled). The presence of concomitant FM was related to higher DAS in patients with RA and AS (DAS28 mean difference 1.24, 95% CI: 1.10, 1.37 in RA; BASDAI mean difference 2.22, 95% CI: 1.86, 2.58 in AS). Concomitant FM was also associated with higher DAS in existing PsA studies. Self-reported, rather than objective, components of DAS appear to be raised in the presence of FM (e.g. tender joint count and Visual Analogue Scale (VAS) pain scores). Conclusion FM is common in RA, AxSpA and PsA. Comorbid FM appears to amplify DAS and could therefore influence management of these rheumatic conditions.

/pdf/concomitant-fibromyalgia-complicating-chronic-inflammatory-3xmuiaosnb.pdf

Concomitant fibromyalgia complicating chronic inflammatory arthritis: a systematic review and meta-analysis.

Fibromyalgia (FM) is one of the most common conditions that rheumatologists encounter. It is characterised by chronic widespread pain, fatigue, sleep disturbances and impaired cognition. The prevalence of comorbid FM among populations with rheumatoid arthritis (RA), axial spondyloarthritis (axSpA) and psoriatic arthritis (PsA) are considerably higher than among the general population, with pooled prevalence estimates of 18–24% in RA, 14–16% in axSpA and 18% in PsA. Prevalence estimates should be interpreted with care as the criteria for FM have not been validated for use in patients with inflammatory arthritis. Comorbid FM appears to affect assessment of disease severity in these conditions, particularly patient-reported outcome measures, and may influence response to treatment. There is a need for better identification, classification and management of FM in the context of inflammatory rheumatic diseases.

The prevalence and impact of comorbid fibromyalgia in inflammatory arthritis.

OBJECTIVES: Vitamin D appears to have significant effects on both innate and acquired immunity and deficiency may be associated with both susceptibility and disease severity in some autoimmune conditions. There has been little focus on the potential immunomodulatory role of vitamin D in AS. This study systematically reviews the evidence for an association between vitamin D deficiency and disease susceptibility and severity in AS. METHODS: A systematic review was conducted using Medline, EMBASE, Web of Science and conference abstracts of the European League Against Rheumatism (2002-13), British Society for Rheumatology (1993-2013) and ACR (2006-13). RESULTS: Fifteen original articles and five conference abstracts met the criteria for inclusion. All were cross-sectional in design. Seven of 11 studies identified lower concentrations of 25-hydroxyvitamin D (25OHD) in AS patients compared with healthy controls. A significant inverse correlation between 25OHD and disease activity was observed in 5 of 11 studies. The majority of studies that failed to demonstrate significant findings used inappropriate statistical methods. CONCLUSION: Cross-sectional studies using appropriate statistical analyses have highlighted that AS is associated with lower vitamin D concentrations. Within groups of AS patients there is some evidence that low vitamin D concentrations are associated with higher disease activity. However, there are insufficient published data to support an immunomodulatory role for vitamin D in AS. Further study with a longitudinal design is required to understand whether optimizing vitamin D in AS has potential as a disease-modifying intervention.

Stephen J Duffield

Papers

The contribution of musculoskeletal disorders in multimorbidity: Implications for practice and policy.

The prevalence of depression in axial spondyloarthritis and its association with disease activity: a systematic review and meta-analysis

Concomitant fibromyalgia complicating chronic inflammatory arthritis: a systematic review and meta-analysis.

The prevalence and impact of comorbid fibromyalgia in inflammatory arthritis.

Systematic review of association between vitamin D levels and susceptibility and disease activity of ankylosing spondylitis