35.4.2.4Immunological Tests

The main immunological markers found in primary SjS are ANA, anti-Ro/SS-A or anti-La/SS-B autoantibodies, rheumatoid factor, hypocomplementemia, and cryoglobulins. ANA are detected in more than 80% of cases of primary SjS. Titers ³1/80 play a central role in differentiating SjS from non-autoimmune causes of sicca syndrome. Anti-Ro/SS-A and La/SS-B antibodies, detected in 40–60% of patients, are closely associated with most extraglandular features [2]. In nearly 50% of cases, patients with primary SjS also present with positive assays for rheumatoid factor [4]. Hypocomplementemia and cryoglobulinemia are two closely related immunological markers that have been linked with more severe SjS. Low complement levels are associated with chronic HCV infection, lymphoma development, and mortality [20–22].

35.4.2.5Other Laboratory Findings

The most frequent routine laboratory features are asymptomatic cytopenias (33%), an elevated erythrocyte sedimentation rate >50 mm/h (22%), and hypergammaglobulinemia (22%) [23]. The most frequent cytopenias detected are normocytic anemia (20%), leukopenia (16%), and thrombocytopenia (13%). The erythrocyte sedimentation rate correlates closely with the percentage of circulating gammaglobulins (hypergammaglobulinemia). Serum C-reactive protein concentrations are usually normal even in the setting of substantial erythrocyte sedimentation rate elevations. Circulating monoclonal immunoglobulins are detected in nearly 20% of patients with primary SjS. Monoclonal IgG is detected most often [24].

35.5Comorbidities and Occupational Disability

The adverse effects on general health, functional status, and quality of life of comorbidity in chronic illness have been amply demonstrated in SjS. Although multiple extraglandular conditions have been recognized in SjS, many of these diseases have been reported only sporadically. Patients with pSjS experience a high prevalence of fatigue, pain, and depression, which could be associated with coexisting comorbidities. Those with primary SjS have a twofold higher risk of diabetes mellitus and a 1.5-fold higher prevalence of hypertriglyceridemia compared with primary care patients [25]. Patients with pSjS are also more likely to have hyperlipidemia (odds ratio [OR] 1.42), cardiac arrhythmias (OR 1.32), headaches (OR 1.47), migraine headaches (OR 1.86), fibromyalgia (OR 1.71), asthma (OR 1.54), pulmonary circulation disorders (OR 1.42), hypothyroidism (OR 2.37), liver disease (OR 1.89), peptic ulcers (OR 1.88), depression (OR 2.57), and psychoses (OR 2.15) [26]. Thus, the impact of SjS on health-related quality of life is substantial.

Primary SjS patients are more likely than the non-SjS adults to not be working due to disability [27]. Furthermore, the prevalence of pain, fatigue, depressed mood,