Occurrence of polymyositis in the county of Gävleborg, Sweden

Inaugural dropped head syndrome and camptocormia in inflammatory myopathies: a retrospective study

OBJECTIVES

Inaugural axial muscle involvement, defined as dropped head syndrome (DHS) and/or camptocormia (CC), is poorly described in inflammatory myopathies (IM). This study aimed to further characterize IM patients with inaugural DHS/CC, their outcome and care management.

METHODS

This retrospective study included IM patients diagnosed between 2000 and 2021. The main inclusion criterion was IM revealed by axial muscle deficit (DHS/CC).

RESULTS

Twenty-seven patients were included; median (IQR) age at first symptoms was 66.0 years (55.5-75.0); 21 were female (77.8%). There were nine IBM, 33.3%, nine overlap myositis (OM, 33.3%), five DM, 18.5%, two immune checkpoint inhibitor-related myositis (7.4%), one focal myositis (3.7%) and one myositis with anti-Hu antibodies (3.7%). Age at first symptoms was ≤70 years in 16 patients (59.3%), including all DM patients and 8/9 OM patients (88.9%). In this group, partial remission of the disease was obtained in 9/16 (56.3%) and complete remission in 1/16 patients (6.3%); regression of DHS/CC was achieved in 3/16 patients (18.8%). Conversely, in the group of 11 patients aged >70 years at first symptoms, there were eight IBM (72.7%). Partial remission was obtained in 5/11 patients (45.5%), the disease was stable in 6/11 patients (54.5%); no complete remission was obtained nor regression of DHS/CC.

CONCLUSION

The analysis of IM patients with inaugural DHS/CC delineates two groups of patients according to the age at first symptoms in terms of clinical and outcome specificities, and proposes an adapted diagnostic and care management approach to prevent long-term complications.

Incidence of systemic autoimmune myopathies and their risk of cancer in Leeds, UK: an 11-year epidemiological study

Objectives

The aims were to identify all incident adult cases of systemic autoimmune myopathies (SAMs) in the city of Leeds, UK, and to estimate the risk of cancer in SAMs as compared with the general population.

Methods

Cases of SAMs were ascertained by review of all muscle biopsy reports from the Neuropathology Laboratory. A review of medical records was undertaken for each case to review the clinical diagnosis and collect epidemiological data such as age, ethnicity, sex and comorbidities, including cancer. Leeds denominator population numbers were publicly obtainable.

Results

A total of 206 biopsy reports were identified and, after review, 50 incident cases were included in the study between June 2010 and January 2021. Of the 50 cases, 27 were male and 23 were female. The mean incidence rate of SAMs in Leeds throughout the study period was 7.42/1 000 000 person-years. The proportion of SAMs cases with a confirmed malignancy was 22%. Compared with the general population, the relative risk of cancer was significantly greater in the SAMs population (31.56; P < 0.01).

Conclusions

The incidence rate of SAMs in Leeds was consistent with data from previous literature; however, disagreement exists between different methods of SAMs case inclusion due to varying clinical criteria and definitions. SAMs are associated with an increased risk of cancer, but the pathogenesis of this relationship still requires investigating. This study supports the practice of malignancy screening and long-term surveillance in patients with SAMs.

A Muscle Biosignature Differentiating Between Limb-Girdle Muscular Dystrophy and Idiopathic Inflammatory Myopathy on Magnetic Resonance Imaging

Background: The overlapping clinical presentations of limb-girdle muscular dystrophy (LGMD) and idiopathic inflammatory myopathy (IIM) make clinical diagnosis challenging. This study provides a comprehensive evaluation of the distributions and characteristics of muscle fat substitution and edema and aims to differentiate those two diseases.

Methods: This retrospective study reviewed magnetic resonance imaging (MRI) of seventeen patients with pathologically proved diagnosis, comprising 11 with LGMD and 6 with IIM. The fat-only and water-only images from a Dixon sequence were used to evaluate muscle fat substitution and edema, respectively. The degrees of muscle fat substitution and edema were graded and compared using the appropriate statistical methods.

Results: In LGMD, more than 50% of patients had high-grade fat substitution in the majority of muscle groups in the thigh and calf. However, <50% of IIM patients had high-grade fat substitution in all muscle groups. Moreover, LGMD patients had significantly higher grade fat substitution than IIM patients in all large muscle groups (p < 0.05). However, there was no significant difference in edema in the majority of muscle groups, except the adductor magnus (p = 0.012) and soleus (p = 0.009) with higher grade edema in IIM. Additionally, all the adductor magnus muscles in LGMD (100%) showed high-grade fat substitution, but none of them showed high-grade edema.

Conclusions: MRI could be a valuable tool to differentiate LGMD from IIM based on the discrepancy in muscle fat substitution, and the adductor magnus muscle could provide a biosignature to categorizing LGMD.

The Impact of Dysphagia in Myositis: A Systematic Review and Meta-Analysis

(1) Background: Dysphagia is a clinical hallmark and part of the current American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) diagnostic criteria for idiopathic inflammatory myopathy (IIM). However, the data on dysphagia in IIM are heterogenous and partly conflicting. The aim of this study was to conduct a systematic review on epidemiology, pathophysiology, outcome and therapy and a meta-analysis on the prevalence of dysphagia in IIM. (2) Methods: Medline was systematically searched for all relevant articles. A random effect model was chosen to estimate the pooled prevalence of dysphagia in the overall cohort of patients with IIM and in different subgroups. (3) Results: 234 studies were included in the review and 116 (10,382 subjects) in the meta-analysis. Dysphagia can occur as initial or sole symptom. The overall pooled prevalence estimate in IIM was 36% and with 56% particularly high in inclusion body myositis. The prevalence estimate was significantly higher in patients with cancer-associated myositis and with NXP2 autoantibodies. Dysphagia is caused by inflammatory involvement of the swallowing muscles, which can lead to reduced pharyngeal contractility, cricopharyngeal dysfunction, reduced laryngeal elevation and hypomotility of the esophagus. Swallowing disorders not only impair the quality of life but can lead to serious complications such as aspiration pneumonia, thus increasing mortality. Beneficial treatment approaches reported include immunomodulatory therapy, the treatment of associated malignant diseases or interventional procedures targeting the cricopharyngeal muscle such as myotomy, dilatation or botulinum toxin injections. (4) Conclusion: Dysphagia should be included as a therapeutic target, especially in the outlined high-risk groups.

Increasing incidence of adult idiopathic inflammatory myopathies in the City of Salford, UK: a 10-year epidemiological study

Objectives

The aim was to identify and characterize all incident adult cases of idiopathic inflammatory myopathies (IIM) between 1 January 2007 and 31 December 2016 in the City of Salford, UK.

Methods

Adults first diagnosed with IIM within the study period were identified by: a Salford Royal NHS Foundation Trust (SRFT) inpatient episode IIM-specific ICD-10 coding search; all new patient appointments to SRFT neuromuscular outpatient clinics; and all Salford residents enrolled within the UKMYONET study. All patients with definite IIM by the 2017 EULAR/ACR classification criteria were included, as were probable cases if consensus expert opinion agreed. Cases were excluded if <18 years of age at disease onset, if they did not meet probable criteria or when probable but expert opinion concluded a non-IIM diagnosis.

Results

The multimodal case ascertainment identified 1156 cases which, after review and application of exclusion criteria, resulted in 32 incident cases during the study period. Twenty-three of 32 were female, with a mean age of 58.1 years. The mean incidence of adult IIM was 17.6/1 000 000 person years, and higher for females than for males (25.2 vs 10.0/1 000 000 person years, respectively). A significant incidence increase over time was apparent (13.6 vs 21.4/1 000 000 person years; P = 0.032). Using EULAR/ACR classification criteria, the largest IIM subtype (21/32) was PM, followed by DM (8/32), IBM (2/32) and amyopathic DM (1/32). Expert opinion subtype differed from EULAR/ACR classification criteria in 19/32 cases.

Conclusion

The incidence of adult IIM in Salford is 17.6/1 000 000 person years, higher in females, and is increasing over time. Disagreement exists between EULAR/ACR-derived and expert opinion-derived IIM subtype assignments.

The incidence of idiopathic inflammatory myopathies in the adult Slovenian population

Idiopathic Inflammatory myopathies (IIM) are rare disorders. The aim of our study was to determine the incidence of IIM in a well-defined Slovenian region. This retrospective study was conducted at the Department of Rheumatology, University Medical Centre Ljubljana, the only secondary/tertiary rheumatology center in a region with a population of 704,342 adults. We identified potential IIM cases by searching the electronic patient records for ICD-10 codes M33, M35.1, M35.8, M60, G72, G73, and J84. We included incipient IIM cases between January 2010 and December 2017, who were at the time of the diagnosis, residents of the inspected region. To avoid under-reporting due to miscoded cases, we obtained a list of the patients who had histological patterns consistent with IIM on muscle biopsy from the Institute of Pathology. The annual incidence rate for IIM was calculated. During the eight-year observation period, we identified 65 IIM cases (72.3% female, median (IQR) patient age 64.8 (54.8-73.2) years). The estimated annual incidence of IIM in the studied population was 11.5 (95% CI 9.0-14.6) per 10⁶ adults, in females 16.2 (95% CI 12.1-21.4), and in males 6.6 (95% CI 4.0-10.2) per 10⁶ adults. The incidence rate of IIM in Slovenia is consistent with data from the literature.

Increased prevalence of celiac disease in idiopathic inflammatory myopathies

OBJECTIVES

Idiopathic inflammatory myopathies (IIM) are often associated with other immune-mediated diseases or malignancy. Some studies have reported a high frequency of celiac disease in IIM. The aim of this study was to investigate the prevalence of celiac disease, systemic inflammatory diseases, and malignancy in a cohort of IIM patients, and estimate the incidence of IIM in the county of Östergötland, Sweden.

MATERIAL AND METHODS

We reviewed medical records and analyzed sera from 106 patients, fulfilling pathological criteria of inflammatory myopathy, for the presence of IgA antibodies against endomysium and gliadin. Antibody-positive patients were offered further investigation with small bowel biopsy or investigation for the presence of antibodies against antitissue transglutaminase (t-TG). The patients were classified according to Bohan and Peter or Griggs criteria. The presence of celiac disease, systemic inflammatory, and malignant diseases was documented.

RESULTS

Four of 88 patients classified as IIM (4.5%) had biopsy-confirmed celiac disease, which is higher than the prevalence in the general population, detected with a similar screening procedure (0.53%). Thirty-three patients (38%) had a systemic inflammatory disease and five (5.7%) a malignancy. The incidence of confirmed IIM in the county of Östergötland was 7.3 per million/year.

CONCLUSIONS

The results highlight the high frequency of associated inflammatory and malignant diseases and confirm an increased prevalence of celiac disease in IIM.

Dermatomyositis: analysis of 109 patients surveyed at the Hospital das Clínicas (HCFMUSP), São Paulo, Brazil

BACKGROUND

Dermatomyositis affects striated muscles, skin and other organs.

OBJECTIVE

To characterize the disease from January 1992 to December 2002, assessing its classification, cutaneous and systemic manifestations, and also laboratory results, therapeutic and prognostic findings compared to those in the literature.

METHODS

Data were obtained from medical records of 109 patients who were classified into five groups: 23 juvenile dermatomyositis; 59 primary idiopathic dermatomyositis; 6 amyopathic dermatomyositis; 7 dermatomyositis associated with neoplasms and 14 dermatomyositis associated with other connective tissue diseases.

RESULTS

Sixty patients were classified as "definite" diagnosis; 33 as "possible"; four as "probable" and 12 and as amyopathic. The average age at diagnosis was 36 years. Cutaneous manifestations occurred in all patients; the most frequent symptom was loss of proximal muscle strength; the most common pulmonary disorder was interstitial lung disease, and gastritis was the most prevalent digestive manifestation. Tumors were documented in 6.42% of cases. Lactate dehydrogenase was the muscle enzyme most frequently elevated in the majority of cases. Skin biopsies were performed in 68 patients; muscle biopsies in 53; and electroneuromyographies in 58 patients. The most commonly used treatment was corticotherapy and the mortality rate was 14.7%.

CONCLUSION

in this sample, the disease appeared in younger individuals, was more frequent in women and the association with cancer was small.

Prevalence and incidence of polymyositis and dermatomyositis in Japan

OBJECTIVES

To estimate the number of patients with polymyositis/dermatomyositis (PM/DM) in Japan and the prevalence rate and incidence rate of the disease.

METHODS

The electronic database in the nationwide registration system on intractable diseases from 2003 to 2010 was utilized to identify the number of prevalent and incident cases of PM/DM. The electronic data entry rate was used to establish the total number of registered cases.

RESULTS

The estimated total number of patients with PM/DM and the prevalence rate in Japan in 2010 were 17,000 and 13.2 per 100,000 population, respectively. The prevalence of PM/DM ranged from 10 to 13 per 100,000 population with a trend toward increasing over time. The incidence of PM/DM was estimated within the range 10-13 per 1,000,000 person-years, except for 2003.

CONCLUSIONS

We report the prevalence and incidence of PM/DM recently in Japan for the first time at the nationwide population level. Because the prevalence seems to be increasing recently, continued monitoring of these epidemiologic features is required.

Dysphonia and dermatomyositis: an unusual manifestation

We report a case of a 39-year-old female with a recent diagnosis of dermatomyositis and dysphonia. Dermatomyositis is a connective tissue disease with multisystem involvement: cardiac, pulmonary, musculoskeletal, gastrointestinal, and dermatologic are the most common. While dermatomyositis affects thousands of individuals in the United States, laryngeal involvement has only been described in a single case report to date.

The ACTN3 R577X polymorphism is associated with inflammatory myopathies in a Mexican population

BACKGROUND

The ACTN3 gene encodes the fast muscle protein α-actinin-3. The ACTN3 R577X polymorphism is a premature stop codon and results in absence of α-actinin-3 in 577XX homozygotes. The aim of this study was to determine the ACTN3 genotype in idiopathic inflammatory myopathies (IIMs).

METHODS

We performed ACTN3 genotyping on 27 patients with dermatomyositis (DM), 10 with polymyositis (PM), and 85 healthy subjects. Muscle enzyme levels of creatine phosphokinase (CPK), lactic dehydrogenase (LDH), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were recorded at the time of diagnosis and recruitment. Genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and the allele frequency was analysed.

RESULTS

A total of 36% of healthy subjects had the ACTN3 577XX polymorphism (α-actinin-3 deficiency), 18% had the 577RR (homozygous wild type) genotype, and 46% 577RX (heterozygous). In DM/PM, 70% had the ACTN3 577XX polymorphism, 6% RR, and 24% RX [odds ratio (OR) 4.12, 95% confidence interval (CI) 1.67-10.33, p < 0.001]. In healthy subjects, the R allele was present in 41% and the X allele in 59% compared to 18% and 82%, respectively, in the IIM group (OR 3.21, 95% CI 1.57-6.66, p < 0.001). Thus, the ACTN3 577X allele seemed to increase the risk of developing IIM, and DM in particular, although this was not related to severity of expression of the phenotype.

CONCLUSIONS

The ACTN3 577X allele appeared to increase the risk of developing IIM; 70% of IIM patients were deficient in α-actinin-3. By contrast, ACTN3 577XX patients seemed to have less severe disease as reflected in lower muscle enzyme levels.

Polymyositis, dermatomyositis, and autoimmune necrotizing myopathy: clinical features

Idiopathic inflammatory myopathies are a heterogeneous group of autoimmune disorders predominantly affecting skeletal muscles, resulting in muscle inflammation and weakness. The 3 most common inflammatory myopathies are polymyositis (PM), dermatomyositis (DM), and inclusion body myositis. This review details the clinical findings noted in PM, DM, and the emerging entity of autoimmune necrotizing myopathy.

Pulmonary manifestations of the idiopathic inflammatory myopathies

Pulmonary involvement in myositis includes interstitial lung disease (ILD), respiratory muscle weakness, aspiration, infections, and drug-induced disease. ILD may precede myositis, and results in increased morbidity and mortality rates. Initial evaluation should include pulmonary function tests and high-resolution computed tomography. Nonspecific interstitial pneumonia (NSIP) is the most common histologic pattern on lung biopsy. Treatment usually consists of a combination of steroids and other immunosuppressive agents, and the response depends on the clinical presentation and underlying histology.

[Clinical manifestations]

Idiopathic inflammatory myopathies are a group of autoimmune diseases that characteristically affect striated muscle. Nevertheless their spectrum of manifestations is very broad, not only muscular. This chapter describes both muscular and extramuscular manifestations of inflammatory myopathies.

Update on idiopathic inflammatory myopathies

The inflammatory myopathies are a group of acquired diseases, characterized by an inflammatory infiltrate of the skeletal muscle. On the basis of clinical, immuno-pathological and demographic features, three major diseases can be identified: dermatomyositis (DM); polymyositis (PM); and inclusion body myositis (IBM). New diagnostic criteria have recently been introduced, which are crucial for discriminating between the three different subsets of inflammatory myopathies and for excluding other disorders. DM is a complement-mediated microangiopathy affecting skin and muscle. PM and IBM are T cell-mediated disorders, where CD8-positive cytotoxic T cells invade muscle fibres expressing MHC class I antigens, thus leading to fibre necrosis. In IBM, vacuolar formation with amyloid deposits are also present. This article summarizes the main clinical, laboratory, electrophysiological, immunological and histologic features as well as the therapeutic options of the inflammatory myopathies.

Factors associated with underlying malignancy in a retrospective cohort of 121 patients with dermatomyositis

Demographic, clinical, and laboratory features that predict underlying malignancy in patients with dermatomyositis (DM) are poorly known. We conducted a retrospective study in all adult patients with a definite (n = 75) or probable (n = 32) diagnosis of DM according to Bohan and Peter criteria or with amyopathic DM (n = 14) who were referred to 2 departments during a 13-year period. The diagnosis of malignancy-associated DM was retained if DM occurred in a context of recently diagnosed malignancy or if a malignancy was diagnosed during the 5 years following the diagnosis of DM. The Kaplan-Meier method was used to assess the cumulative incidence rates of underlying malignancy during the first 5 years of DM. Factors associated with malignancy in patients with DM were identified by Cox proportional hazards models. During the study period, 121 patients fulfilled the inclusion criteria (median age, 52 yr; range, 19-77 yr; women: 70%). For 29 of them, the diagnosis of malignancy-associated DM was retained. The cumulative incidence rate of malignancy was 21 +/- 4% and 28 +/- 5%, 1 year and 5 years after the diagnosis of DM, respectively. The median duration of follow-up of the 92 patients with no malignancy diagnosed was 36 months (range, 1-140 mo). In multivariate analysis, independent factors associated with an underlying malignancy in patients with DM were an age at diagnosis >52 years (hazard ratio [HR], 7.24; 95% confidence interval [CI], 2.35-22.31), a rapid onset of skin and/or muscular symptoms (HR, 3.11; 95% CI, 1.07-9.02), the presence of skin necrosis (HR, 3.84; 95% CI, 1.00-14.85) or periungual erythema (HR, 3.93; 95% CI, 1.16-13.24), and a low baseline level of complement factor C4 (HR, 2.74; 95% CI, 1.11-6.75). Lastly, low baseline lymphocyte count (<1500/mm(3)) was a protective factor of malignancy (HR, 0.33; 95% CI, 0.14-0.80). Taken together, these data may help physicians focus on a group of patients who might benefit from extensive evaluation for malignancy.

Retrospective review of the clinical manifestations and outcomes in Puerto Ricans with idiopathic inflammatory myopathies

BACKGROUND

The idiopathic inflammatory myopathies (IIM) are a heterogeneous group of conditions characterized by chronic inflammation of muscles, resulting in skeletal muscle weakness. Racial differences are apparent in the clinical manifestations and outcome of IIM. No previous studies have been conducted to evaluate the clinical manifestations and outcome of Puerto Ricans with IIM.

OBJECTIVE

The objective of this study was to describe demographic characteristics, clinical features, and functional outcome of Puerto Rican patients with IIM.

METHODS

Medical records at a university medical center were reviewed retrospectively to collect data regarding demographic factors, initial presentation, diagnostic tests, serologic markers, treatment, and disease course. A Functional Grading Scale was administered to 40 of the patients with IIM to determine their functional status.

RESULTS

Fifty patients with IIM were identified. Eight patients had polymyositis (PM), 23 patients had dermatomyositis (DM), 2 patients had DM/PM with coexistent malignancy, 12 patients had juvenile DM, and 5 patients had DM/PM with an associated other rheumatologic disease. At diagnosis, proximal muscle weakness was present in all patients, 15 (30%) had myalgias, 5 (10%) patients had dysphagia, and 87% had elevation of serum muscle enzymes. Visceral involvement was rare. Interstitial fibrosis was identified in only 2 patients (1 juvenile DM and 1 PM). Twenty-six patients (51%) achieved complete remission. The mean score for the Functional Grading Scale was 28.6 (maximum 30). The lowest scores were seen for patients with disease duration of less than 2 years.

CONCLUSION

Puerto Ricans with IIM in this survey showed a low presence of visceral involvement, high remission rate, and low mortality.

Physiopathologie des myopathies inflammatoires primitives

COMMON ELEMENTS: Primary inflammatory myopathies consist of dermatomyositis (DM), polymyositis (PM) and inclusion body myositis (IBM). They have certain characteristics in common: progressive muscle weakness and mononuclear inflammatory infiltrates in the muscle. DIFFERENT MECHANISMS: They may be distinguished by their histological features which also reflect their different underlying pathogeneses. The mechanism of DM would be complement-mediated microangiopathy, the inflammatory infiltrate of which would be secondary to ischemic phenomena, whereas in PM the muscle fibres are damaged by cytotoxic CD8 T lymphocytes. The factors triggering-off these two forms of myositis remain unknown. IBM may be a degenerative disease with accumulation of a variety of proteins within the fibres. The inflammatory infiltrate, which is similar to that seen in PM, may be a reaction to accumulated proteins.

Interstitial lung disease, a common manifestation of newly diagnosed polymyositis and dermatomyositis

OBJECTIVES

To estimate the prevalence and predictors of interstitial lung disease in newly diagnosed polymyositis and dermatomyositis.

METHODS

A prospective study in which consecutive patients with newly diagnosed poly- and dermatomyositis, regardless of clinical symptoms of pulmonary disease, were investigated with chest x ray, high resolution computed tomography (HRCT), pulmonary function tests, and biochemical and autoantibody analysis. Patients with inclusion body myositis, malignancy, other defined inflammatory connective tissue diseases (CTDs), or antibody profile indicating other CTDs were excluded.

RESULTS

Between March 1998 and September 2000, 26 new cases of poly- or dermatomyositis were diagnosed; 17 of those patients were included in the study. Interstitial lung disease (ILD), defined as radiological signs on chest x ray examination/HRCT or restrictive ventilatory defect, were found in 11 (65%) patients and were more common in men than in women. Arthritis and occurrence of anti-Jo-1 antibodies were found more often in patients with ILD than in those without. There was no statistically significant association between respiratory symptoms, other serological or laboratory variables and ILD.

CONCLUSIONS

ILD is a common early manifestation in patients with poly- and dermatomyositis and is not always related to clinical symptoms. Chest x ray examination, HRCT, pulmonary function tests, and analysis of anti-Jo-1 antibodies should be included in the initial investigation of patients with myositis regardless of respiratory symptoms.

Idiopathic inflammatory myopathies - myositis

The inflammatory myopathies - myositis - encompass a heterogeneous group of chronic muscle disorders of unknown origin and with varying prognoses. New clinical phenotypes of myositis have been identified since the most widely used classification criteria were proposed in 1975. Based on clinical and histopathological features, inclusion body myositis was identified. Furthermore, the myositis-specific autoantibodies may also identify different clinical phenotypes and serve as prognostic markers. The different classifications and inclusion criteria that have been used in different studies make some epidemiological data uncertain. In order to improve our knowledge of causative factors, as well as of pathogenic mechanisms, there is a need for revision and also for an international acceptance of the classification criteria. During recent years, our knowledge has increased regarding the role of some genetic and environmental factors that could affect susceptibility for developing myositis as well as the prognosis. Whether there is an association between myositis and malignancies has been a subject of controversy for many years and recent epidemiological data have brought some clarification on this issue.

Idiopathic inflammatory myopathies: epidemiology, classification, and diagnostic criteria

Epidemiologic studies have helped to define the prevalence and incidence of PM, DM, and IBM and have highlighted differences in risk between men and women and in the age at onset for the different forms of myositis. Additionally, these studies have shown that there is a substantially higher risk of PM and DM in certain racial groups which is likely to be genetically determined. These differences are all likely to be fundamental in terms of the pathogenesis of these diseases but, as yet, their full significance remains uncertain. They do, however, suggest that the interplay between genetic and environmental initiating factors is different in the three disorders. Additional population-based studies in homogeneous racial groups, in parallel with studies of susceptibility genes for autoimmune disease, such as those encoding the MHC and inflammatory cytokines, are needed to throw further light on the role of genetic factors in the pathogenesis of the IIMs [47]. Because of the paucity of epidemiologic data on IBM, further studies are required to determine the degree of variation in prevalence in different populations and racial groups, as well as the consistency of the male association and age spectrum of manifestations of the disease. The particularly strong association with DR3 in this form of IIM [48] clearly points to the importance of genetic factors in pathogenesis, but further studies of DR3-associated genes in the MHC and of other candidate genes are needed to define more precisely the genes that convey susceptibility to the disease in different racial groups. Epidemiologic studies also have the potential to identify environmental factors that may play a part in disease initiation in genetically susceptible individuals. Seasonal patterns of disease onset have been reported, particularly in patients with DM [49-51] as well as seasonal variation in the frequency of relapses [52], pointing to the probable involvement of intercurrent infections, ultraviolet light exposure, or other environmental factors in disease initiation and reactivation. Further prospective studies are required to determine the contribution of environmental exposures and how they interact with genetic susceptibility factors to lead to myositis. One of the major limitations of a number of the previous epidemiologic studies is the lack of precision in the diagnostic criteria used and the classification of cases of IIM. The Bohan and Peter criteria [1] which were used in most studies after 1975, were introduced before IBM was recognized as an entity distinct from PM; most of the published incidence and prevalence figures for PM are therefore likely to be inaccurate. Multicentered, interdisciplinary, prospective studies, incorporating comprehensive clinical, laboratory, and pathologic information, are needed to develop and validate better diagnostic and classification criteria and to determine the true prevalence and incidence of the many forms of IIM.

Influence of age on characteristics of polymyositis and dermatomyositis in adults

In a retrospective study of 79 consecutive patients, we evaluated characteristics of polymyositis (PM) and dermatomyositis (DM) and compared clinical presentation, biochemical findings, histologic changes, evolution, complications, and mortality rate of elderly patients (aged > or = 65 yr) and younger patients (aged < or = 64 yr) at the onset of PM/DM. We found a high prevalence of PM/DM in elderly patients: 23 patients (29%) were aged 65 years or over. We also found that esophageal involvement (34.8% versus 16.1%, respectively) and bacterial pneumonia related to both ventilatory insufficiency and esophageal impairment (21.7% versus 5.4%, respectively) were more common in elderly patients compared with younger patients, resulting in increased morbidity and mortality rates. Moreover, malignancy frequency was higher in elderly patients compared with younger patients (47.8% versus 9.1%, respectively, p = 0.0001), particularly patients with DM (10/11). Fifty percent of malignancies were colon malignancies in elderly patients. Erythrocyte sedimentation rate, C-reactive protein, fibrinogen, and ferritin levels were also higher in the elderly patient group compared with the younger group, and the presence of serum hypoprotidemia, hypoalbuminemia, and anemia was more frequent. Finally, PM/DM complete remission was less frequent (13.6% versus 41.1%) and the mortality rate (47.8% versus 7.3%) was higher in elderly patients than in younger patients. The main causes of death in elderly patients were bacterial pneumonia, due to ventilatory insufficiency and esophageal impairment, and malignancies. Our findings therefore indicate that PM/DM-related esophageal and lung involvement should be systematically searched for in elderly patients. Esophageal manometry and pulmonary function tests should become an integral part of initial evaluation in elderly patients for early detection of impairment. Moreover, as we observed a marked overrepresentation of colon cancer in elderly patients with DM, we suggest that the search for malignancies in elderly patients with DM should include lower gastrointestinal tract investigations.