The photometric latex test for rheumatoid factors in patients with rheumatoid arthritis. II. Clinical evaluation.

The photometric latex test (PLT) for the detection of rheumatoid factors has been clinically evaluated. PLT titers have been closely studied in relation to clinical and laboratory parameters by means of parametric and nonparametric statistical methods. An analysis of the sensitized sheep cell test (SSC) titers has also been undertaken. The subjects comprised 377 patients with rheumatoid arthritis (RA) and 120 controls. The medical data recorded included sex, age, diagnosis, anatomical stage, functional class, duration and course of the disease, presence of the American Rheumatism Association (ARA) criteria, blood sedimentation rate, red and white blood counts, haemoglobin concentration, total protein content, serum protein levels, and SSC and PLT titers. A multivariate stepwise regression analysis with eight normally distributed variables was made. In accordance with previous findings, a significant correlation was shown to exist between the serum protein levels and the development of the RA when the anatomical stage, functional class and course of the disease were used as parameters of disease activity. In the RA patients there was also correlation between the serologic titers and the serum protein levels, and the anatomical stage, functional class and course of the disease, and the sedimentation rate, thus showing that titers can also serve as a measure of the inflammatory process. There was a significant correlation between the number of ARA criteria and the titers in the RA patients but not in the controls. The course of the disease correlated with the serum titers and other inflammatory parameters, a finding showing that the course of the disease is an important diagnostic parameter with possible prognostic value. Correlation was also demonstrated between the white blood count and the titers. It is concluded that the sedimentation rate, albumin and gamma-globulin levels, and PLT titer are the best parameters of disease activity. The titer values are not only of diagnostic importance but have prognostic value as regards the severity of the disease.

The photometric latex test for rheumatoid factors in patients with rheumatoid arthritis. I. correlation with other serologic tests.

The photometric latex test (PLT) for the detection of rheumatoid factors (RF) has been correlated with the sensitized sheep cell test (SSC) and the latex slide test (LST). A total of 377 sera from patients with rheumatoid arthritis (RA) and 120 sera from control subjects were examined. When the PLT was carried out on the native sera at a lower buffer ionic strength (0.05 M), agglutination was noted in over 99% of cases, indicating interaction of complement with human immunoglobulin bound to the latex particle surface. Although thermal inactivation eliminated most of the complement agglutination, an increase in ionic strength (0.5 M) was found to be essential for measuring only RF agglutination. The serologic data were analysed statistically by computer. A highly significant correlation was found between all serologic tests and RA sera, but there was no such correlation with the control sera. The specificity of all tests was generally over 90% and did not vary significantly, but the sensitivity varied from 52.0% to 71.1%, confirming that about one-third of all RA patients are seronegative. The tests were analysed for their total diagnostic capability. The PLT with native sera at higher ionic strenght proved to be the most sensitive, but with thermally inactivated sera it had a better diagnostic capacity. The SSC test appeared to be less sensitive and of lower diagnostic validity. Rapid LST tests were clearly inferior to PLT tests. The PLT can be used as a reliable and straightforward serologic method of diagnosis in RA, especially when carried out at a higher ionic strength and with thermally inactivated sera. It should be given preference over other serologic tests for RF and could well become standard practice in rheumatologic serology as a substitute for the SSC test.

Diclofenac sodium (Voltaren): results of a multi-centre comparative trial in adult-onset rheumatoid arthritis.

A short-term trial has been performed under double-blind conditions in 50 adult patients with rheumatoid arthritis to compare diclofenac sodium (Voltaren) with both indomethacin and placebo for efficacy and tolerability. The duration of the trial was two weeks and was a between-patient comparison of 25 mg t.i.d. diclofenac sodium, 25 mg t.i.d. indomethacin or placebo using a double-dummy technique. Forty-eight patients completed the trial. In the majority of parameters examined, diclofenac sodium was superior to placebo and indomethacin in therapeutic effect. One patient was withdrawn from the trial because of intolerance to indomethacin and one other because of severe joint pain under indomethacin therapy. Neither active compound caused clinically significant changes in blood picture or urine analysis.