Proposed Methodology
Overview
The study will be conducted because specific, reliable and predictable diagnostic tests for Rheumatoid Arthritis (RA) are lacking (Niewold, Harrison & Paget, 2007). Yet, studies have shown that RA is the most common form of autoimmune rheumatoid illness and affects thousands of people in the US and millions in the world (Dollah, Yaacob, Ismail & Hussin, 2011). However, the recently developed ELISA technique based on the Anti-cyclic citrullinated peptide (anti-CPP) antibodies against RA proteins in the human serum is a reliable diagnostic tool for RA (Dollah et al., 2011).
The study will be conducted after approval by the internal review board of the university hospital. The study will determine the effectiveness of anti-cyclic citrullinated peptide (Anti-CPP) antibodies in the diagnosis of rheumatoid arthritis (Dollah et al., 2011). In particular, the effectiveness of the antibodies will be examined and tested to establish its specificity and sensitivity based. The test will be based on the American College of Rheumatology criteria as the gold standard (Niewold et al., 2007).
It will be conducted between January 2015 and March 2015 using 260 participants with arthritis (140 with rheumatoid arthritis and 120 with arthralgia or other forms of arthritis that does not meet the American College of Rheumatology Criteria for rheumatoid arthritis).
Study design
A cross sectional study will be conducted between January and March 2015. The proposed study targets a sample of patients visiting the local university hospital with different forms of arthritis. The clinical group will consist of patients of rheumatoid arthritis who have satisfied the American College of Rheumatology criteria for rheumatoid arthritis. The control group will be made up of the patients of arthritis or arthralgia who do not meet the ACR criteria for RA.
Inclusion/exclusion criteria
The study will be conducted at the arthritis section of the university hospital. It will target patients who have been diagnosed with the condition. Secondly, participants must be between 25 and 65. A patient who fails to meet this criterion will be excluded from the study. In addition, all participants to be included in the clinical group must meet the ACR criteria for rheumatoid arthritis. On the other hand, the control group will be expected to have been diagnosed with arthralgia or arthritis.
Materials and methods
Materials
The study seeks to enroll 260 patients (170 males and 90 females) with a mean age of 45± 15.0 years, randomly selected from a total study population of 3644 patients presenting at the rheumatoid department of the university hospital between January 2012 and September 2014. Of the total 260 patients, it is expected that 140 (53.85%- 56 females and 84 males) will be included in the AR group because they will have satisfied the ACR criteria for AR.
The non-RA patients will be composed of the other 120 patients (46.15%- 76 males and 44 females) because they will not have satisfied the ACR criteria for AR. In addition, it is expected that the non-AR group will include patients with diverse types of arthritis (other than AR), including spondyloarthropathy, systematic lupus erythromatosus, osteoarthritis, mixed connective tissue disease, primary Sjogren’s syndrome, adult onset Still’s disease, gouty arthritis and Behcet’s disease (Dollah et al., 2011).
Upon inclusion in the study sample, each patient’s gender, age and clinical characteristics will be recorded. All the patients will be required to provide serum within the first day of the study. Laboratory experts in the rheumatoid department will be assigned the task of taking serum from each subject. The samples will be stored at -20oC while waiting for the start of the assay (Dollah et al., 2011). The use of the laboratory, human samples and the criteria will be under the approval of the university hospital as a clinical and academic study and following all the ethical criteria set by the institution.
Methods
Initially, each serum sample will be tested for the anti-CPP antibodies as well as the IgM rheumatoid factor (IgM RF) using the conventional Enzyme-Linked Immonosorbent Assay (ELISA) (Niewold et al., 2007). The ACR criteria will be used to evaluate the specificity and sensitivity of the tests. The ELISA method will be based on the second-generation ELISA technique developed by the INOVA Diagnostics Corporation of San Diego, California.
All the samples will be assayed in duplicate in order to decrease the chances of errors. In addition, each sample will be evaluated based on an upper limit of 20IU/mL in order to follow the instructions given by the manufacturer (Dollah et al., 2011). The determination of the IgM Rheumatoid Factor (RF IgM) will be accomplished using the nephelometry with a cut-off level of 15IU/mL (Dollah et al., 2011).
Data analysis
For each test, the observations made with the ELISA method will be recorded. The standard Mann-Whiteney U test will be the gold standard for testing the subgroups, where the variables will be expressed as the median interquartile range in the graph. Variables will also be expressed in percentages.
The SPSS statistical tool will be used to compare the specificity and sensitivity of the tests based on the chi-square test. In addition, the study will determine other aspects such as negative predictive values, specificity and sensitivity of the diagnosis and the area ‘under the curve’ using the SPSS statistical tool. All the tests will be two-tailed and tested at the significant level of 0.05 (Niewold et al., 2007).
The table below will be used to describe the demographic data and the clinical characteristics of the participants for the samples of the two categories (RA and non-RA samples).
Table 1: description of the clinical characteristics and demographic data of the participants with rheumatoid arthritis against those with non-rheumatoid arthritis in the proposed study.
To determine the specificity and sensitivity of the test, the table below will be used to record and describe the frequencies of the antibodies and RF both categories of participants.
Table 2: Tabulated representation of the frequencies of the anti-CPP antibodies as well as the RF in the participants with rheumatoid arthritis against those with non-rheumatoid arthritis in the proposed study.
References
Dollah, R., Yaacob, A., Ismail, A. H., & Hussin, C. M. (2011). Anti-CCP Antibodies: A Better Diagnostic Tool for Rheumatoid Arthritis. International Medical Journal, 18(1), 216-233.
Niewold, T. B., Harrison, M. J., & Paget, S. A. (2007). Anti-CCP antibody testing as a diagnostic and prognostic tool in rheumatoid arthritis. Qjm, 100(4), 193-201.