Objective-The objective of the EPISER study was to estimate the prevalence of rheumatoid arthritis (RA), low back pain, hand and knee osteoarthritis (OA), and fibromyalgia in the adult Spanish population, and to assess the impact of these diseases on function and quality of life, and use of health and social resources. Methods-2998 subjects aged 20 years or above were randomly selected by stratified multistage cluster sampling from the censuses of 20 municipalities. Trained rheumatologists carried out structured visits at which subjects were asked about rheumatic symptoms and sociodemographic characteristics, completed validated instruments for measuring function (HAQ) and quality of life (SF-12), and underwent a standardised physical examination. Cases were defined by previously validated criteria. Results-The estimated prevalences with 95% confidence intervals were as follows: RA lifetime cumulative: 0.5% (0.3 to 0.9); low back pain: 14.8% (12.2 to 17.4); symptomatic knee OA: 10.2% (8.5 to 11.9); hand OA: 6.2% (5.9 to 6.5); fibromyalgia: 2.4% (1.5 to 3.2). Most conditions significantly impaired function and quality of life. Conclusions-The EPISER study has internal and external validity for application of the results to the adult Spanish population. The diseases studied aVect a significant proportion of the population, with various degrees of impact on disability and quality of life resulting in a significant number of physician visits, work disability, and medication use. (Ann Rheum Dis 2001;60:1040-1045 Musculoskeletal diseases are one of the main causes of disability in the developed world and consume a large amount of health and social resources. The proportion of the population disabled by rheumatism ranges from 2.8% in the United States to 8% in Great Britain. [1][2][3] Nevertheless, for reasons that are not clear, these conditions are not commonly the target of epidemiologists and thus epidemiological studies on the occurrence and impact of musculoskeletal diseases compared with diseases aVecting the cardiovascular or pulmonary systems, for instance, are infrequent.Most of the epidemiological data on rheumatic diseases at the national level come either from a small number of sampling areas considered representative of the country or are secondary data from national health surveys in which information about rheumatic diseases relies mainly on self-reporting.

Objective. To identify new genes associated with susceptibility to rheumatoid arthritis (RA), using a 2-stage genome-wide association study.Methods. Following a liability-based study design, we analyzed 317,503 single-nucleotide polymorphisms (SNPs) in 400 patients with RA and 400 control subjects. We selected a group of candidate SNPs for replication in an independent group of 410 patients with RA and 394 control subjects. Using data from the 3 previous genome-wide association studies in RA, we also looked for genomic regions showing evidence of common association signals. Finally, we analyzed the presence of genome-wide epistasis using the binary test implemented in the PLINK program.Results. We identified several genomic regions showing evidence of genome-wide association (P < 1 ؋ ؊5). In the replication analysis, we identified KLF12 SNP rs1324913 as the most strongly associated SNP (P ‫؍‬ 0.01). In our study, we observed that this SNP showed higher significance than PTPN22 SNP rs2476601, in both the genome-wide association studies and the replication analyses. Furthermore, the integration of our data with those from previous genome-wide association studies showed that KLF12 and PTPRT are the unique loci that are commonly associated in 3 different studies (P ‫؍‬ 0.004 and P ‫؍‬ 0.002 for KLF12 in the Wellcome Trust Case Control Consortium study and the Brigham and Women's Rheumatoid Arthritis Sequential Study genome-wide association study, respectively). The genome-wide epistasis analysis identified several SNP pairs close to significance after multiple test correction.Conclusion. The present genome-wide association study identified KLF12 as a new susceptibility gene for RA. The joint analysis of our results and those from previous genome-wide association studies showed genomic regions with a higher probability of being genuine susceptibility loci for RA.Rheumatoid arthritis (RA) is one of the most prevalent autoimmune diseases in the world (1). In RA, chronic inflammation of the synovial joints leads to progressive articular damage, which can result in major functional disability (2). The etiology of RA is unknown, but several family aggregation and twin studies (3,4) clearly demonstrate a heritable component of the disease. Part of this genetic component of susceptibility has been consistently associated with the HLA class II locus variation. The remaining 50-75% of the genetic component includes several other genomic regions that are more difficult to identify due to their lower penetrance or more complex models of action (5,6).

The present findings establish the PDE3A-SLCO1C1 locus as a strong genetic marker of anti-TNF therapy response.

It has been shown that males with spondyloarthritis tend to suffer from more severe spinal disease while females are more likely to have peripheral joint involvement. Nevertheless, gender-related differences have not been thoroughly explored in psoriatic arthritis (PsA). In PsA, males accumulate more peripheral and axial joint damage compared to women. However, it is not clear whether these findings are secondary to differences in occupational physical activity, hormonal changes, or other factors. The present study analyzed the differences in clinical expression of PsA between men and women. We have also evaluated the possible existence of gender-linked differences in the distribution of genes and polymorphisms within the major histocompatibility complex and whether patients' age at the onset of psoriasis established any differences in these aspects. Women suffered more polyarthritis, greater functional impairment, and a larger number of swollen joints during followup. We appreciated a differential expression of certain MHC genes according to gender and age at onset of psoriasis. Our results point to the need to include patient's age at the onset of psoriasis and gender as key stratification elements in future studies of genetic associations in PsA.

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