There were only a few studies in recent years aiming at the evaluation of bone health in patients with IIMs. An overview of the most recent evidence on the presence of osteoporosis and fractures of patients with IIM is presented in Table
1. In the different cohort studies, the prevalence of osteoporosis was between 23.5 and 26.9%, while the prevalence of osteopenia was between 47.4 and 62.7%. The presence of both vertebral and non-vertebral fractures was found between 17.5 and 75% of the patients. In a Brazilian case-control study, it was proved that osteoporosis was more frequent in female DM/PM patients than in controls measured by DXA in both lumbar spine and the femoral neck. Moreover, a high prevalence of fractures was found in patients in comparison to healthy subjects (17.9 vs. 5.1%,
p = 0.040; OR = 3.92; CI 95%:1.07–14.33) [
23]. In a large population-based retrospective analysis from Taiwan, the authors found that patients with DM/PM were 2.99 times more likely to develop osteoporosis than those without DM/PM. After a 13-year follow-up period, the cumulative incidence for osteoporosis in the DM/PM cohort was 5.35% higher than the incidence for the comparisons. Interestingly, the osteoporosis risk was independent of corticosteroids and immunosuppressant treatment. However, some essential data was lacking, including detailed demographic information on smoking habits, alcohol consumption, body mass index, socioeconomic status, physical activity, vitamin D deficiency, calcium/vitamin D supplements, and bone-strengthening medication [
22]. Data from a single-center study revealed that female gender, low serum albumin levels at onset, high Myositis Disease Activity Assessment Visual Analogue Scales (MYOACT) score, and high cumulative prednisolone dose were associated with lower BMD results [
20]. Similarly, during a long-term follow-up in a single UK center, patients with long-term prednisolone doses of more than 5 mg had a significantly shorter time to develop osteoporosis/osteopenia (
p<0.0001) than those with less than 5 mg [
24]. In a more recent study by Gupta et al., in a relatively young cohort, asymptomatic vertebral fractures were present in nearly half of the patients. This was much higher than it was found from lupus patients from the same center, without ethnic and environmental differences; thus, it seems plausible that a higher fracture rate is due to disease-specific factors [
21•]. Regarding the affected bones, the 11
th and 12
th thoracic vertebrae were the most commonly (30.4%) fractured. The only available longitudinal data were recently published by this group [
26••]. They found in the original, but a smaller patient population that the fracture rate increased from 46 to 61.29% after 3 years. In addition, those patients who had previous vertebral fractures had a higher risk of developing a new fracture when compared with those with no vertebral fractures (76.5% vs. 14.28%, RR: 5.35). The number of fractures correlated significantly with age, T scores at the L4 level, and lower third of radius on DXA, myositis damage index (MDI), and modified MDI, where osteoporotic fracture item in MDI was removed. Neither conventional nor disease-related variables differed between progressors and non-progressors [
26••]. In our Hungarian center, IIM patients with older age and longer disease duration were investigated and compared with age and gender-matched rheumatoid arthritis (RA) patients. The prevalence of osteoporosis was found to be significantly higher in the myositis group (7% vs. 13.5%,
p: 0.045), but the fracture prevalence was similar in the two groups (75% vs. 68%) [
19•]. In contrast with the data by Gupta et al., the most commonly affected vertebras were the 7
th and 8
th thoracic and the 5
th lumbar in this cohort (unpublished data), which might be the consequence of different age or ethnicity of the two populations. The fracture rates were independently associated with age in the myositis group, and with lower BMD results in the RA patients. Interestingly, the cumulative steroid dose was significantly higher in the myositis group but showed no correlation with the presence of vertebral fractures. The number of prevalent fractures was significantly correlated to poorer physical function detected by Health Assessment Questionnaire (HAQ) and poorer health status detected by Short Form-36 (SF36) in the myositis group [
19•]. Therefore, it can be concluded that both the prevalence and the risk of osteoporosis and fractures in patients with IIM are higher than in healthy individuals and that fractures significantly affect the quality of life. The results showed a good concordance with data of groups from different regions of the world, suggesting that the high fracture prevalence is a global myositis-dependent feature. Even in younger patients, asymptomatic fractures might present in the early phase of the disease and this could increase the risk of development of further fractures.
Table 1
The epidemiology and predictors of osteoporosis and fractures in idiopathic inflammatory myositis patients
Vincze et al. (2019) [ 19•] | Hungary | 52 | 57.46 | 82.7 | 76.67 | 26.39 | 13 | 60 | 13.5 | | 75 | (+) age |
(-) physical function (HAQ) |
(-) Quality of life (SF36) |
| China | 38 | 52.8 | 84.2 | | 23.8 | 4.7 | 47.4 | 23.7 | (+) female sex | | |
(-) serum albumin |
(+) cumulative steroid dose |
(+) Disease activity (MYOACT) |
Gupta et al. (2018) [ 21•] | India | 100 | 35.5 | 82 | 23.5 | 22.2 | 3 | 62.7 | 26.9 | | 46 | (+) age |
(+) postmenopausal years |
(-) T and Z scores at the lower third of the radius |
Wei-Sheng Lee (2016) [ 22] | Taiwan | 1179 | 43.9 | 65.4 | | | | | | (+) DM/PM history | 17.5 | (+) age |
de Andrade et al. (2012) [ 23] | Brazil | 40 | 51.93 | 100 | 77.5 | 27.76 | 9.62 | | 25 | (+) age | | (-) weight |
| | | | | | | | | (-) weight | | (+) postmenopausal status |
| | | | | | | | | (+) postmenopausal status | | |
| UK | 55 | 41 | 66 | | | 9 | 32.7% | (+) steroid dose | | |
| Hungary | 105 | 50.6 | 76 | | | 8.9 | | 25 | | | |