Background Patients with primary Sjögrens' syndrome (PSS) suffer from severe alterations in both the quality and quantity of saliva and tears. Body water represents around 50–55% of the body weight. Tears contain 98% of water and saliva 99.5%.
Objectives To evaluate the percentage of total body water (TBW) among patients with PSS and to assess its correlation with sicca symptoms.
Methods We included 85 patients with PSS and 85 historical non diabetic controls matched by gender, age (±3 years) and body mass index (±1kg/m2) (BMI). We assessed the presence of sicca symptoms, Schirmer-I test, non-stimulated whole salivary flow (NSWSF) and ocular staining. We also evaluated the ocular and oral domains of the ESSPRI, a validated scale for symptoms (a higher score implies worst symptoms). We obtained the TBW percentage with a bioelectric impedance analysis (BIA-SECA-514, Hamburgo).
Results 80% were women, mean age 54.8±13.7 years and mean disease duration 11.5±7.52 years. The percentage of TBW was similar among patients and controls (PSS 46.85±4.6 vs. 46.9±4.5, p=0.88). Among the patients, the TBW negatively correlated with age (ρ=-0.25, p=0.02), disease duration (ρ=-0.30, p=0.005), BMI (ρ=-0.78, p=0.001) and the ocular component of the ESSPRI (ρ=-0.28, p=0.01), but not with the NSWSF or the ESSPRI oral component. When we compared the patients in the 25% percentile (group with the lowest % of water) vs. the remaining patients, the former group was older (56.6±8.1 vs. 54±14.2, p=0.02), with longer disease duration (12.4±5.9 vs. 10.8±7.12, p=0.03), lower scores at the Schirmer test (1 (range 0–8) vs. 2 (range 0–9), p=0.01), higher BMI (31.1±5.1 vs. 23.7±2.9, p=0.001) as well as with higher ESSPRI ocular domain scores (8.3±1.4 vs. 6.7±2.5, p=0.007). With the linear regression analysis, the variables that remained associated with the TBW were disease duration (β -0.22, p=0.001), BMI (β-0.76, p<0.001) and the ocular domain of the ESSPRI (β-0.15, p<0.001).
Conclusions Patients with PSS had similar TBW percentage than controls. However among patients with PSS, the TBW had a negative correlation with the intensity of ocular symptoms independently of disease duration, age and BMI.
Guyton, Arthur C. (2006). Textbook of Medical Physiology (11th ed.). Philadelphia: W.B. Elsevier Saunders. p. 295. ISBN 0–7216–0240–1.
Disclosure of Interest None declared