Axial spondyloarthritis (axSpA) is an important cause of chronic low back pain. AxSpA affects approximately 1% of the population and is thought to be widely underdiagnosed (12). Patients with axSpA can be classified as two subtypes: ankylosing spondylitis (radiographic axSpA) or nonradiographic axSpA (nr-axSpA). Diagnosis of axSpA is often challenging, especially in early stages of disease. AxSpA is an important disabling disorder especially in elderly patients, early diagnosis and treatment have an significant effect on quality of life. This is the first study evaluating frailty and treatment responses in late-onset axSpA patients.
The current study demonstrated that female gender was predominant in late-onset axSpA. Half of patients had peripheral arthritis. 19 percent patients had cervical vertebrae involvement. More than half of late-onset axSpA patients had nr-axSpA. No relationship was found between female gender and disease duration, radiographic axSpA and BASDAI. Also there were no relationship between radiographic sacroiliitis and disease duration, HLA B27 and BASDAI. HLA B27 positivity was related with high serum CRP levels. When compared with early onset axSpA, late-onset patients had higher frequency of female gender, peripheral arthritis and cervical vertebrae involvement. Early-onset patients had higher HLA B27 positivity. There were no relationship in radiographic sacroiliitis, disease duration, enthesitis, lomber vertebrae involvement, BASDAI and CRP.
In addition to these findings, the results of our study demonstrate significant improvement in frailty with optimal treatment in late-onset axSpA patients. At the end of the 6 months frailty scores of 37(88%) late-onset axSpA patients improved,with a change in CSF by ≥ 1, as accepted clinically meaningfull change in previous studies ( 13). Frailty is a state of vulnerability to poor resolution of homeostasis following a stress which results a decline in multiple physiological systems (14). Multiple organ systems, like brain, endocrine system, immun system, skeletal muscle and enviromental factors are related to frailty(15). There are few tools for measuring the degree of frailty. In this study we used Clinical Frailty Scale because it is easy to use and and can be readily adapted in clinical practice. It is clear from current study that most patients with axSpA have significant improvement in frailty scores with treatment. And that will result in notable acquisitions on both quality of life and health care resources.
ASAS classification criteria is very useful in the diagnosis of nonradiographic patients,but does not permits the diagnosis of late-onset patients. According to ESSG data, the frequency of late onset SPA is estimated at 4–8% in SPA population (16). In a survey of the German Ankylosing Spondylitis Society, 6% of over 14000 patients had the beginning of symptoms after age 40 years (17). Louise et al showed that almost 10% of the patients with SpA had late-onset of symptoms (18). When we look at the clinical features there are some differences from early-onset patients. National Registry of Spondyloarthritis of the Spanish Society of Rheumatology (REGISPONSER) database were evaluated 1257 AS patients, forty-four (3.5%) had disease onset at age ≥ 50 years. The late-onset AS patients had higher frequency of neck involvement and peripheral arthritis. There was no differences in genetic expression, disease activity, or radiological progression between two groups (19)There are also data showing that HLA B27 positivity is lower in this group of patients (20). Despite all these differences, the course of the disease seems similar. Calin et al showed that age at onset had no significant effect on radiological progression and disease activity (21). Therefore, treatment approach should not be different from early onset patients.
According to the data obtained from observational studies and real life experiences, it is thought that AS in women is still underdiagnosed. Baraliakos et al. showed that fibromyalgia patients only rarely fulfill classification criteria for axSpA but some axSpA patients also fulfill fibromyalgia criteria and more common in AS than nr-axSpA. As they mentioned before, assessment instruments in axSpA are not disease-specific (22). So we think it is not clear if fibromyalgia is a confounding factor or we are more inclined to diagnose female patients with fibromyalgia. In our study, the frequency of female patients was significantly higher in late-onset axSpA group. However, there was no relationship between female gender and disease activity and symptom duration.
Nonsteroidal anti-inflammatory drugs (NSAIDs) are effective and first choice in the treatment of axSpA. Approximately 60% of AS patients treated with NSAIDs have significantly improvement in low back pain (23, 24). NSAIDs also has a disease modifying effect on SpA. GESPIC cohort showed that continuous treatment with NSAIDs, reduced radiological progression in the spine in patients with AS and this effect is more prominent in patients with elevated CRP levels, elevated ESR, high ASDAS-CRP and high ASDAS-ESR (25, 26). When comparing NSAID response rates, AS and nr-axSpA patients seems to had similar response rates (27). Our results also suggest that in late-onset SpA patients, NSAIDs are as effective as in early-onset patients. However, the tolerability of NSAIDs in elderly patients is always a debate. On the other hand, several researches suggested that NSAIDs in the elderly are effective for the treatment of different musculoskeletal diseases and gastrointestinal adverse events can be reduced by using proton pump inhibitors (28,29). Also the use of biologic drugs remains limited due to comorbidities and potential risk of side effects. This is probably due to the lack of clinical data. There are few studies investigating the efficacy and safety of anti-TNF therapy in elderly patients. In a study conducted in Korea including 236 late onset AS patients, there were no differences in the drug retention rates based on the type of bDMARD and there were no diferences among each bDMARD type (30). Also Fleischmann et al showed that with long term etanercept use, the incidence of advers events and malignancies was not significantly raised in elderly patients(31). Our study also supported that elderly patients tolerated well both NSAIDs and anti-TNF therapy and had similar response rates in comparison with young patients.
From our results it is evident that late-onset axSpA patients have some different features from early-onset patients. Female gender predominancy, late-onset symptoms, lower HLA B27 positivity and low rate of radiograhic sacroiliitis cause delay in diagnosis and treatment of elderly patients and they can rapidly become in need of care over time. Morover,cervical vertebrae involvement leads to vertigo and balance disorders so the risk of fall increases. Considering all this consequences, delay in diagnosis and treatment of elderly patients result in substantial consumption of health care resources. With prompt treatment most patients became non-frail and live without help.