This cross sectional study included 30 patients (26 males and 4 females), recruited from the outpatient clinic of Rheumatology and rehabilitation department in our institution from November 2018 to August 2019 according to the following criteria:
Patients diagnosed as ankylosing spondylitis, according to the modified New York criteria  as relayed from records of inpatients in Rheumatology department.
Patient with known associated chest diseases and non-immune mediated pulmonary pathology e.g., old or active tuberculosis.
Patients with history of smoking.
All cases were subjected to the following:
Informed written consent was obtained from all patients prior to enrollment.
All data related to patients was collected and included: age, gender, duration of disease, history of smoking and tuberculous infection.
Assessment of disease activity using Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) : The index consists of six questions. The responses were marked on a horizontal line measuring 10 cm (from 0 to 10 cm), where the patient evaluates how he feels in relation to each item in the last week, marking on the scale: if the patient is fine (“very well”), he/she marks zero cm, gradually increasing until “very poor”, corresponding to a 10-cm mark. The six questions comprising BASDAI are as follows: (1) How would you describe the degree of fatigue or tiredness you have had?; (2) How would you describe the overall level of neck, back and hip pain related to your illness?; (3) How would you describe the overall level of pain and edema (swelling) in other joints, apart from neck, back and hip?; (4) How would you describe the overall level of discomfort you felt to the touch or compression in the painful regions of your body?; (5) How would you describe the intensity of morning stiffness you have had, from the time you wake up?; (6) How long does your morning stiffness take, from the time you wake up?(
Protocol for HRCT chest study
All patients underwent scans at 16-MDCT scanner, Somatom, Emotion Siemens.
Patients were scanned in supine position in full inspiration. I.V. contrast wasn’t administered.
After acquisition, acquired images were transferred to dedicated post-processing workstation where volumetric measurements were performed.
Scans were assessed by three radiologists of 20, 10 and 3 years of experience. They were blinded to the clinical and laboratory data. Results were based on consensus agreement.
HRCT scans were evaluated for presence, distribution, and extent of HRCT abnormalities.
Standard CT criteria for ILD were used to establish ILD diagnosis by presence of its characteristic abnormalities (e.g., subpleural opacities, parenchymal bands, thickening interlobular septa, irregular pleural surface, honeycombing) and determining their extent and distribution pattern.
Multidetector high resolution CT protocols were applied with the patients in the dorsal decubitus position, during maximum inspiration, by using an 16-channel MDCT system. Contiguous axial slices of CT scans were obtained at 5 mm intervals, with 5 mm colimation, 130 Kvp, and an automatic tube modulation at 125 mA. All images were obtained at window levels appropriate for lung parenchyma (window width 1000 HU; window level –700 HU). Sagittal and coronal reconstructed images were performed.
Data was entered on the computer using "Microsoft Office Excel Software" program (2010) for windows. Data was then transferred to the Statistical Package of Social Science Software program, version 24 (IBM SPSS Statistics for Windows, Version 24.0. Armonk, NY: IBM Corp.) to be statistically analyzed.
Data presented using range, mean, standard deviation, median, quantitative variables, frequency, and percentage for qualitative ones.
Pearson correlation coefficients were calculated to assess the association between disease duration, activity and presence of thoracic findings of AS.
P values less than 0.05 were considered statistically significant.