86.- The state of the art in the damage index development and utility
90.- Uso de las probabilidades en medicina

The American College of Rheumatology classification criteria for SLE have facilitated the comparison of patient populations from different centers, however, they do not address the issue of disease activity. Decker commented on our inability to describe in quantifiable terms the state of a patient in any given afternoon in the clinic. The assessment of disease activity in important both for clinicians to make appropriate therapeutic decisions and for researchers who seek correlation of laboratory data with disease activity, as well as for therapeutic trials.

There have been many attempts to develop criteria for disease activity in SLE.1 Few have been tested for reproducibility among different raters. Prior to 1987, the Lupus Activity Criteria Count (LACC) was the only measure validated against physicians judgment However, this measure did not a low for gradation of disease activity.

There validated instruments for the assessment of disease activity in SLE have been described. The Systemic Lupus Activity Measure (SLAM), was development in Doston, based on the opinions of the members of the Lupus Council of the American College of Rheumatology, and  includes primarily clinical features, and no specific serologic test for lupus.2 The British Isles Lupus Activity Group (BILAG) measure, was based on an intent to treat approach, derived from a group of rheumatologist from the British Isles, and includes few laboratory test as well.3 The Systemic Lupus Disease Activity Index (SLEDAI) was derived during a conference on prognosis studies in lupus held in Toronto in 1985, which included rheumatologists from 10 centers in North America.4 The SLEDAI includes both clinical and laboratory features of SLE, and is weighted to account for “severity”. These three instruments, SLAM, BILAG and SLEDAI have been compared by members of the groups which developed them, both on live patients and one case scenarios, and proved to be comparable and reliable, although the SLEDAI appeared to be more sensitive to disease activity over time.5,6 The SLEDAI was further tested in “naive” observers and proved to be reliable.7

The SLEDAI proved reliable in a study by Petri et al who tested the validity of activity measures in the routine clinic visit.8 They included the SLEDAI, as well as the Lupus Activity Index (LAJ), which had not been previously validated. The LAI is simple measure, which does not include specific definitions of disease manifestations, but relies solely on clinician’s impressions of activity in a particular system. It is not at all surprising, therefore, that  the use of a physician global assessment of disease activity correlated better with the LAI than the SLEDAI, although both proved reliable. Another version, called the CORE index, which included variables present in both SLEDAI, LAI and BILAG correlated best.

Guzman et al9 compared the Lupus Activity Criteria Count (LACC), the SLEDAI and a mexican version of the SLEDAI (MEX-SLE DAI) and showed that these indices showed convergent validity and sensitivity to change. This instrument thus lends further validity to the SLEDAI.

Another instrument was recently described by the Consensus Study Group of the European Workshop for Rheumatology Research.10 The European Consensus Group study included 20 centers from 14 countries. The activity measure was developed through consensus, and included 15 items derived through univariate and multivariate analysis of 704 patients. The resultant index, termed ECLAM (European Consensus Lupus Activity Measurement) is very similar to the SLEDAI. ECLAM was tested and compared with the SLAM, BILAG, SLEDAI, and another measure SIS in an additional group of 75 patients with SLE. All the compared indices were closely correlated at 2 time points.11

Thus, several disease activity indices have been validated. The SLAM, BILAG, SLEDAI, and ECLAM appear comparable, and the LAI and MEX-SLEDAI at least were comparable to the SLEDAI. All these indices  include the same variables of disease activity seen in patients with SLE, but vary in the weight that each variable may obtain. It is therefore crucial, that any studies of new laboratory measures in lupus, therapeutic trials, studies of outcome and prognosis in these patients include a measure activity which has been validated and is sensitive to change over time.
Each of the instruments has been shown to be sensitive to change at least in one study. However, it seems that the SLEDAI is the easiest to use in every day practice, because of the fact that it includes only one page, and has the definition clearly identified on the same page. Although one does not necessari1y receive the resu1ts of the serological tests immediately, one can certainly assess the clinical features of the SLEDAI in the clinic, and decide whether changes are required. Thus, the disease activity index, while designed for research use, is quite useful for patient follow-up in the individual practice

References

  1. Liang. MII, Socher SA, Roberts YN, Esdaile. JM: Measurement of systemic lupus erythematosus activity in. clinical research. Arthritis Rheum 1988; 31: 918-825.
  2. Liang. MII, Socher SA,  Larsen MG, Schur PII: Reliability and validity of 6 systems for the clinical assessment of disease activity in SLE. Arthiritis Rheum 1989; 32: 1107-1118.
  3. Symmons DPM, Coppock. JS, Bacon PA, Bresnihan B, Isenbeeg DA, Maddison P, Mcllugh N, Snaith MS, Zoa. A: Development and assessment of a computerized index of clinical disease activity in systemic lupus erythematosus. Quart J Med 1988; 69: 927-93 7.
  4. Bombardier C, Gladman FD, Urowitz MB, Caron D, Chang CII: Derivation of the SLEDAI. A disease activity index for lupus patients, The Committee on Prognosis Studies in SLE. Arthritis Rheum 1992, 35: 630-640.
  5. Gladman DD, Goldsmith CII, Urowitz MB, Bacon P, Bombardier C, Chang CII, Isenberg D, Kalunian K, Liang, M, Maddison P, Nived O, Richter M, Snaith M, Symmons D, Zoma A: Cross-cultural Validation of Three Disease Activity Indices in Systemic Lupus Erythematosus (SLE). J Rheumatol 1992, 19: 608-611.
  6. Gladman D, Goldsmith C, Urowitz M, Bacon P, Bombadier C, Isenberg D, Kulunian K. Liang M, Maddison P, Nived O, Richter M, Snaith M, Symmons D, Zoma: A: Sensitivity to change of 3 SLE disease activity indices: International validation. Arthritis Rheum 1990, 33 (suppl 9): S82 (J Rheumatol, press).
  7. IIawkcr G, Gabriel S, Bombardier C, Goldsmith C. Caron D, Gladman DD: A Reliability Study of SLEDAI: A Disease Activity Index for Systemic Lupus Erythematosus (SLE), J Rheumatol 1993, 20: 657-660.
  8. Petri M, IIellmann D, Hochberg M: Validity and reliability of lupus activity measures in the routine clinic setting. J Rheumatol 1992, 19: 53-59.
  9. Guzman J, Cardiel MII, Arce-Salinas A, Sanchez-Guerrero J, Alarcon-Segovia D: Measurement of disease activity in systemic lupus erythematosus, Prospective validation of 3 clinical indices. J Rheumatol  1992, 19: 1551-1558.
  10. Vitali C, Dencivelli W, Isenberg DA, Smolen JS, Snaith ML, Sciuto M. Neruy R, Bombardieri S: Decease activity in systemic lupus erythematosus: report of the Consensus Study Group of the European Workshop for Rheumatology Research. II. Identification of the variables indicative of disease activity and their use in the development of an activity score. The European Consensus Study Group for Disease Activity in SLE. Clin Exp. Rheumatol 1992, 10: 54 1-547.
  11. Bencivelli W, Vitali C. Isenberg DA, Smolen JS, Snaith ML, Sciuto M. Bombardieri S: Disease activity in systemic lupus eruthematosus: report of the Consensus Study Group of the European Workshop for Rheumatology Research. III. Development of a computerized clinical chart and its application to the comparison of different indices of disease activity. The European Consensus Study Group for Disease Activity in SLE. Clin Exp Rheumatol 1992, 10: 549-554.

Revista Archivos de Reumatología VOL 5 N° 2 /1994
Se publica con autorización de la
Sociedad Venezolana de Reumatología

86.- The state of the art in the damage index development and utility
90.- Uso de las probabilidades en medicina
Dra. Dafna Gladman
Sociedad Venezolana de Reumatología