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ORIGINAL ARTICLE
Year : 2015  |  Volume : 15  |  Issue : 1  |  Page : 26-30

A comparative study of functional pulmonary involvement in patients with rheumatoid arthritis in a semi-urban population of Eastern India


Department of Physiology, Burdwan Medical College and Hospital, Burdwan, West Bengal, India

Date of Web Publication19-Jan-2015

Correspondence Address:
Arunima Chaudhuri
Department of Physiology, Burdwan Medical College and Hospital, Krishnasayar South, Borehat, Burdwan - 713 102, West Bengal
India
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DOI: 10.4103/1319-6308.149528

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  Abstract 

Background: Pulmonary involvement in rheumatoid arthritis (RA) is frequent although not always clinically recognized. Objectives: The present study was conducted to measure the alterations of lung function parameters with the help of pulmonary function tests in patients of RA in a semi-urban population of a developing country. Materials and Methods: This pilot study was conducted in a time span of 1 year on 156 subjects in Burdwan Medical College after taking Institutional Ethical Clearance and informed consent of the subjects. A total of 106 diagnosed cases of RA was taken as cases, and 50 normal individuals were selected as a control. Different parameters studied were forced vital capacity (FVC), FVC%, forced expiratory volume in 1 s (FEV1), FEV1%, FEV1/FVC, forced expiratory flow (FEF25-75), FEF25-75%, peak expiratory flow rate (PEFR), PEFR%. Results: FVC, FEV1, FEV1/FVC, FEF25-75, PEFR, and PEFR% were significantly decreased (P < 0.05) in cases. But there was no significant difference in FVC%, FEV1%, and FEF25-75%. Among RA patients, 56.6% were normal, 15.09% had obstructive lung diseases (OLD), and 28.3% had restrictive lung diseases (RLDs). Conclusions: RA was found to be of significant importance in the development of restrictive, as well as OLD. RLD was significantly higher in patients positive for rheumatoid factor and anticyclic citrullinated peptides antibody. Since RA, affects general population with a prevalence of 0.5-1% and lung function gets affected in 30-40% of cases, the patients might be screened for respiratory abnormalities from the time of diagnosis using spirometry.

  Abstract in Arabic 

دراسة مقارنة لوطائف الرئة عند المرضى المصابين بالتهاب المفاصل الروماتودي في واحد من المجتمعات شبه الحضرية في شرقي الهند.
خلفية: تعقيدات وظائف الرئة عند مرضى التهاب المفاصل الروماتودي أمر متكرر الحدوث إلاّ إنه قد لا يعرف سريرياً.
هدف الدراسة: أجريت هذه الدراسة بهدف قياس عوامل التغيرات في وظائف الرئة مستعينة باختبار وظائف الرئة في مرضى التهاب المفاصل الروماتودي في مجتمع شبه حضري في إحدى الدول النامية.
مواد الدراسة و منهجها: أجريت هذه الدراسة التجريبية غلى 156 عينة على مدى عام كامل في كلية بوردوان الطبية ( الهند) بعد موافقة أفراد العينة ، و قد اختبرت 106 من حالات التهاب المفاصل الروماتودي عينات للدراسة، و اختيرت 50 حالة من الأصحارء كعينة ضابطة. و قد استخدمت الدراسة عددا من العوامل المتغيرة كالقدرة الحيوية القسرية للرئة ، و حجم الزفير القسري.
النتائج: انخفضت كل قياسات وظائف الكلى بما فى ذلك القدرة الحيوية للرئة و حجم الزفير القسري في جميع الحالات ، إلاّ أنه لم تظهر فروقات مهمة في النسبة المئوية للقدرة الحيوية القسرية والنسبة المئوية لحجم الزفير القسري في 75% من عينات الدراسة.

و قد أظهرت نتائج الدراسة أن:. 56.6% كانت نتائجهم طبيعية ، 15.09% كانوا يعانون مرض من الانسداد الرئوي، 28.3% كانوا يعانون أمراض الرئ' المقيدة.

الخلاصة : أظهرت الدراسة أن لالتهاب المفاصل الروماتودي تأثيرا كبيرا في مضاعفات مرض الانسداد الرئوي و مرض الرئة المقيدة على حد سواء. كما اتضح أن الإصابة بمرض الرئة المقيدة أعلى عند المصابين بالتهاب المفاصل الروماتودي. واتضح أن التهاب المفاصل قد ظهر على ما بين1-0.5% من أفراد المجتمع , وتأثرت مابين 30 - 40% من الحالات بتعقيدات وطائف الرئة ، و قد اسخدم جهاز قياس التنفس في فحص صعوبات التنفس .




Keywords: Obstructive and restrictive lung disease, pulmonary function tests, rheumatoid arthritis


How to cite this article:
Chattopadhyay K, Chaudhuri A, Hussain SA, Biswas A. A comparative study of functional pulmonary involvement in patients with rheumatoid arthritis in a semi-urban population of Eastern India. Saudi J Sports Med 2015;15:26-30

How to cite this URL:
Chattopadhyay K, Chaudhuri A, Hussain SA, Biswas A. A comparative study of functional pulmonary involvement in patients with rheumatoid arthritis in a semi-urban population of Eastern India. Saudi J Sports Med [serial online] 2015 [cited 2019 Aug 20];15:26-30. Available from: http://www.sjosm.org/text.asp?2015/15/1/26/149528


  Introduction Top


Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by persistent joint inflammation resulting in joint damage and loss of function. The extra-articular manifestations of RA are characterized by destructive polyarthritis and extra-articular organ involvement. [1],[2],[3] Extra-articular features and nonarticular complications of RA are common and are generally related to greater morbidity and mortality. They need to be recognized early and managed promptly. [2]

Patients of RA have a high prevalence of pulmonary functional abnormalities. Abnormal lung functions in these patients may vary from interstitial lung diseases (ILDs) to both large and small airway diseases. Lung abnormalities show both restrictive and obstructive patterns. Pulmonary involvement in RA is frequent although not always clinically recognized. Pleural disease is common but, usually, asymptomatic; autopsy studies have reported pleural involvement in 50% of cases, with only 10% clinically detected. ILD is associated with RA; however, the prevalence and natural history are undefined. [1],[2],[3],[4],[5],[6] ILD is an increasingly recognized complication of RA contributing to significantly increased morbidity and mortality. [7],[8] Pulmonary involvement contributes significantly to the morbidity and mortality of patients of RA and is the second most common cause of death, first being infections. It has been suggested that patients of RA may benefit from serial pulmonary function tests (PFT) to allow early identification of pulmonary diseases. Several studies have reported that patients with RA have an increased incidence of abnormal findings in PFT. [9],[10] The presence of RF and anticyclic citrullinated peptides (CCP) antibody is associated with more severe disease including erosive and destructive arthropathy and extra-articular involvement and presence of accompanying diseases increase the mortality. [10]

Early studies identified a high postmortem incidence of RA-ILD, and this was subsequently supported by high-resolution computed tomography (HRCT) which confirmed that up to 25% of RA patients had ILD. ILD is the only complication of RA reported to be increasing in prevalence, and it has been shown to account for around 6% of all RA deaths. The main value of pulmonary function testing is in the assessment of the change over time. Patients with static disease will have stable test results while those with a progressive decline in lung volume or gas transfer are likely to have progressive disease. PFT is safer and more sensitive than repeat HRCT. [5],[6] Hence, in a developing country like India PFT plays a pivotal role in patient management. HRCT is not still available in many centers, and it is expensive as compared to PFT.

The frequency of extra-articular manifestations in RA differs from one country to another. RA is more common in females, but extra-articular manifestations of the disease are more common in males. [1],[2] Although there are several studies regarding the effects of RA on the respiratory system, but no specific types of lung abnormalities have been identified so far in relation to respiratory system particularly in eastern India. Hence, the present study was conducted to assess the respiratory function abnormalities in patients of clinically established cases of RA. A proper knowledge in respect to this affection may propel early screening of pulmonary function abnormalities in these patients, which in turn, may decrease the social burden of the disease by reducing morbidity and mortality.

Objectives

The present study was conducted to measure the alterations of lung function parameters with the help of PFT in patients of RA in a semi-urban population of a developing country.


  Materials and methods Top


This pilot cross-sectional study was conducted in a time span of 1 year on 103 subjects (age, sex, and body mass index-matched) in Burdwan Medical College after taking Institutional Ethical Clearance and informed consent of the subjects. On first appointment, particulars of the subject, chief complaints, personal history, family history, history of past illness, and treatment history of the subjects were carefully recorded. General physical examinations were done. Before the time of the test, the patients were not permitted to have the cigarette, nicotine, coffee, or drugs. Anthropometric measurements were carried. Basal heart rate and blood pressure were recorded.

Inclusion criteria

Clinically established cases of RA in the age group of 30-60 years of both sexes were included as cases. AntiCCP positive patients (both rheumatoid factor positive or negative patients as per American Rheumatism Association Criteria) were selected as cases. AntiCCP negative and RA factor negative patients without any evidence of any lung diseases were selected as a control. [10] All known cases and newly diagnosed outpatients who had visited the rheumatology clinic consecutively were enrolled in the study. All the patients were consuming at least one disease-modifying antirheumatic drugs. [9]

Exclusion criteria

Subjects with a history of cardiovascular diseases, systemic illnesses which involve the respiratory system or alter vital parameters, respiratory tract infections within last 4 weeks were excluded. Smokers, grossly anemic subjects, subjects involved in professions that may affect respiratory functions and having the dyspnea were not included. Sample size calculation was performed on the basis of previous studies with 40% increase at the spirometric abnormalities in RA patients compared with normal people. [9] Sample size was calculated with Epi info 6 software with α = 0.05 and β = 0.2. Therefore, 100 patients with RA and 50 normal controls were calculated. Finally, 106 patients and 50 healthy controls were included in the study.

In 2010, the 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) RA Classification Criteria [10],[11],[12],[13] were introduced, and cases of RA in our study were included following these criteria. The "new" classification criteria, jointly published by the ACR and the EULAR established a point value between 0 and 10. Every patient with a point total of 6 or higher is unequivocally classified as an RA patient, provided he had synovitis in at least one joint and given that there is no other diagnosis better explaining the synovitis. Four areas are covered in the diagnosis: Joint involvement, designating the metacarpophalangeal joints, proximal interphalangeal joints, the interphalangeal joint of the thumb, second through fifth metatarsophalangeal joint and wrist as small joints, and shoulders, elbows, hip joints, knees, and ankles as large joints.

Different parameters of spirometer studied were forced vital capacity (FVC), FVC%, forced expiratory volume in 1 s (FEV1), FEV1%, FEV1/FVC, forced expiratory flow (FEF25-75), FEF25-75%, peak expiratory flow rate (PEFR), PEFR% and were recorded accordingly. Subjects will be demonstrated steps of spirometry, and a trial run was given. Computerized Spirometer (Model - RMS Helios-401) was used. Lung functions were diagnosed according to the following criteria:

  • Normal: The test was interpreted as within normal limits if both the FVC and the FEV1/FVC ratio were in the normal ranges
  • Obstructive abnormality: The test was interpreted as showing the obstructive abnormality when the FEV1/FVC ratio was below the normal range
  • Restrictive abnormality: A reduction in the FVC without a reduction of the FEV1/FVC ratio reflects a restriction of the volume excursion of the lung. [9] Those who had an FEV1/FVC of <70% were identified as having obstructive disease; its severity was determined according to FEV1 decline. The patients with normal FEV1/FVC and decreased FVC (<80%) were diagnosed as having restrictive disease; its severity was determined by the decrease in FVC. [9]


Statistical analysis

The computer software "Statistical Package for the Social Sciences (SPSS) version 16 (SPSS Inc. Released 2007. SPSS for Windows, Version 16.0. Chicago, SPSS Inc.) was used to analyze data. The standard deviation (SD) values for the mean were calculated. All the test results obtained in the different groups were expressed as mean ± SD. For all analysis probability values (P < 0.05) were considered as statistically significant, and P < 0.01 were considered as statistically highly significant. Unpaired Student's t-test and Chi-square tests were used.


  Results Top


In our study, 106 clinically established cases of RA patients and 50 normal subjects were enrolled as chosen following same exclusion and inclusion criteria. Of all cases, there were 82 female and 24 male patients, percentage of which was 77.36 and 22.64, respectively. Similarly, of all subjects selected as control, 35 were female, and 15 were male, percentage of which were 70 and 30, respectively. Using Chi-square test, we did not find any significant difference in sex between the two groups (P were 0.39 and 0.532, respectively). Mean ages of subjects included for cases were 42.5 ± 7.5 and those for control were 45.8 ± 6.5, P was 0.149, so the subjects in both groups were age matched. Mean body mass index of subjects selected for cases were 21.53 ± 1029 and for control was 21.57 ± 1.34 with a P value of 0.886, which was not significant. We studied spirometric parameters like FVC, FVC%, FEV1, FEV1%, FEV1/FVC, FEF25-75, FEF25-75%, PEFR, and PEFR% in both cases and control. FVC, FEV1, FEV1/FVC, FEF25-75, PEFR, and PEFR% were significantly decreased (P < 0.05) in cases as compared to controls. But there was no significant difference in FVC%, FEV1% and FEF25-75% between the two groups [Table 1]. FVC (2.55 ± 0.70 vs. 3.53 ± 0.38, P < 0.000), FEV1 (2.15 ± 0.57 vs. 3.41 ± 0.35, with P < 0.000), FEV1/FVC (82.31 ± 14.93 vs. 95.43 ± 1.98, P < 0.000), FEF25-75 (2.38 ± 0.70 vs. 5.93 ± 0.42, with a P < 0.000), PEFR (4.46 ± 1.58 vs. 5.96 ± 0.39 and P < 0.000), PEFR% (68.26 ± 18.57 vs. 79.16 ± 3.93 with P < 0.000) were lower in cases as compared to controls.
Table 1: Different spirometric parameters in both case and control groups

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In this study, we found among rheumatoid arthritis patients 56.6% were normal, 15.09% had obstructive lung disease and 28.3% had restrictive lung disease. In the control group, all participants were normal (**P < 0.01).


  Discussion Top


Pulmonary involvement is a well-recognized and important extra-articular manifestation of RA. [1],[2],[3],[4],[5] In RA patients, both airflow obstruction and bronchial responsiveness were significantly increased compared with controls in our study. The patients of RA had a high prevalence of pulmonary abnormalities. RA can produce diffuse inflammation in the lungs and the membranes of the lung (pleura). [6],[7],[8],[9] Pulmonary involvement contributes significantly to the morbidity and mortality of patients of RA. Several studies have reported that patients with RA have an increased incidence of abnormal findings in PFT. [9],[10] Abnormal lung functions in these patients may vary from ILDs to both large and small airway diseases. Lung abnormalities also show both restrictive and obstructive patterns. Small airways pathologies were a common finding in several studies in RA patients. [1],[2],[3],[4],[5],[6],[7],[8],[9],[10] The present study also demonstrates similar findings.

A case-control study was conducted by Zohal et al., [9] on 99 patients with RA in a rheumatology clinic in northwest Iran. A total of 65 age- and sex-matched healthy controls was also studied. The mean (±SD) age of the patients was 46 (±10.5) years. Mean ages of subjects included for cases were 42.5 ± 7.5 in our study. Three (3%) patients had mild restrictive, two (2%) patients mild obstructive, and one (1%) patient moderate obstructive diseases. [9] We found among RA patients, 56.6% were normal, 15.09% had obstructive lung disease (OLD) and restrictive lung disease (RLD) was found in 28.3% cases. This higher incidence of respiratory abnormalities in the present study may be due to geographical variation of the population studied as has also been seen in previous studies. [1] A significant decrease of FEF25, FEF50, FEF75, and FEF25-75 was observed in patients compared with the control in the study conducted by Zohal et al. [9] FVC, FEV1, FEV1/FVC, FEF25-75, PEFR, and PEFR% were also significantly less (P < 0.05) in subjects selected as cases in our study.

A study was conducted in 2013 [14] to identify demographic and clinical predictors of OLD and RLD in patients with established inflammatory polyarthritis (IP) and to compare the prevalence of respiratory symptoms in patients with IP and the general population. A total of 421 patients with IP underwent a spirometry test 15 years after inclusion in the Norfolk Arthritis Register (NOAR). Logistic regression analyses were performed to assess the predictive ability of demographic and clinical characteristics obtained at inclusion in NOAR and to assess their association with OLD or RLD at 15 years (age- and gender-adjusted). The prevalence of OLD and RLD was compared with a matched population (1:4) of people participating in the European Prospective Investigation of Cancer-Norfolk, a representative sample of the general population in Norfolk, UK. It was concluded that OLD, but not RLD, is more prevalent in the IP population than in the general population. RLDs were significantly higher among RA cases in our study also.

Fuld et al. [15] performed a longitudinal study (time span: 10 years) of pulmonary function in asymptomatic, nonsmoking patients with active RA requiring disease-modifying drugs. The prevalence of pulmonary function abnormality was higher than expected compared with a reference population which is similar to the results of our study. When assessed by group means and compared with reference values, reduced diffusing capacity of the lung for carbon monoxide (DLCO) and increased ratio of residual volume (RV) to total lung capacity (TLC) [RV/TLC] were the only abnormalities to develop over the study period. Logistic regression did not identify any meaningful relationship between disease characteristics and PFT abnormality. We did not carry a longitudinal study, so we failed to predict the changes in pulmonary functions in the patients over time which is a limitation of the present study.

Chen et al. [6] used chest HRCT and PFT to identify asymptomatic, preclinical forms of RA-ILD that may represent precursors to more severe fibrotic lung disease. They analyzed chest HRCTs in consecutively enrolled RA patients and subsequently classified these individuals as RA-ILD or RA-no ILD. Coexisting PFT abnormalities (reductions in percent predicted FEV1, FVC, TLC, and/or DLCO) were also used to further characterize occult respiratory defects. About 61% (63/103) of RA patients were classified as RA-ILD based on HRCT and PFT abnormalities while 39% (40/103) were designated as RA-no ILD. A total of 57/63 RA-ILD patients lacked symptoms of significant dyspnea or cough at the time of HRCT and PFT assessment. Compared with RA-no ILD, RA-ILD patients were older and had longer disease duration, higher articular disease activity, and more significant PFT abnormalities. HRCT represented an effective tool to detect occult/asymptomatic ILD that is highly prevalent in unselected, university-based cohort of RA patients. We only used PFT tests to detect respiratory abnormalities in our study, as we did not have HRCT facility, use of which could have increased the strength of our study.

Future scope and limitations

This was a pilot cross-sectional project conducted in a population attending medicine outdoor of Burdwan Medical College and may not be a true representation of the population at a large. Hence, we are planning for multicentric longitudinal studies for better management and greater benefit of patients.


  Conclusions Top


From the present study, RA was found to be of significant importance in the development of restrictive and OLD. RLDs were significantly higher in patients positive for rheumatoid factor and antiCCP antibody. Since RA, an autoimmune disorder, affects general population with a prevalence of 0.5-1% and its effects are debilitating with lung function getting affected in 30-40% of cases, the patients might be screened for respiratory abnormalities from the time of diagnosis by using spirometer. This early detection of abnormal lung parameters may help in changing treatment protocols and reduce morbidity and mortality.

 
  References Top

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