127 LETTERS 4. Burns JC, Geha RS, Schneeberger EE, Newburger JW, Rosen FS, Glezen LS, Huang AS, Natale J, Leung DYM: Polymerase activity in lymphocyte culture supernatants from patients with Kawasaki disease. Nature 323:814-816, 1986 5 . Pelton BK, North M, Palmer RG, Hylton W, Smith-Burchnell C, Sinclair AL, Malkovsky M, Dalgleish AG, Denman AM: A search for retrovirus infection in systemic lupus erythematosus and rheumatoid arthritis. Ann Rheum Dis 47:20&209, 1988 6. Mack D, Sninsky JJ: A sensitive method for the identification of uncharacterized viruses related to known virus groups: hepadenavirus model system. Proc Natl Acad Sci USA 85:69774981, 1988 Clinical outcome in patients receiving nonsteroidal antiinflammatory drugs To the Editor: The very detailed study by Cush et a1 (1) illustrates a major dilemma for rheumatologists treating relatively early rheumatoid disease, namely, how can the patients who will improve spontaneously be identified? The authors report that, among patients given a nonsteroidal antiinflammatory drug, those who responded in terms of their acute-phase reactants and other markers of disease activity also had an improvement in their clinical indices. This is not surprising if one believes that the acute-phase response is largely a product of cytokines released as an integral part of the pathologic process. A more important finding, however, was that responding patients could not be distinguished from the nonresponding ones on the basis of their clinical features at onset. One crucial feature in these patients was not examined, however; namely, their genetic backgrounds. We and others have studied this question in patients with early arthritis (2) and have shown that, despite apparent similarities in clinical features, the patients who have persistent disease can be distinguished on a genetic basis from those who have self-limiting disease. Not only do patients with persistent disease have a much higher frequency of the so-called “disease-related’’ epitope of the third hypervariable region of DRpl (2), but there are differences between the two groups in the prevalence of a defect of the enzyme system responsible for sulfur oxidation (3). Therefore, although it is true that from the data presented in Cush et al’s report, one could not predict clinical outcome, I think it would be appropriate to make every effort to stratify for known genetic factors. Certainly, this would provide a further means of interpreting the data in the absence of a placebo control group. Paul Emery, MD University of Birmingham Birmingham, UK Cush JJ, Jasin HE, Johnson R, Lipsky PE: Relationship between clinical efficacy and laboratory correlates of inflammatory and immunologic activity in rheumatoid arthritis patients treated with nonsteroidal antiinflammatory drugs. Arthritis Rheum 33:623633, 1990 Salmon M, Emery P, Wordsworth BP, Tunn EJ, Bacon PA, Bell JI: HLA Dw4 is associated with persistence rather than the induction of rheumatoid arthritis. Submitted for publication Emery P, Bradley H, Arthur V, Trueba Yanes T, Tunn EJ, Waring RH: Poor sulphoxidation: a genetically determined factor associated with persistent disease in rheumatoid arthritis (abstract). Br J Rheumatol 28:49, 1989 Trapeziometacarpal osteoarthrosis in a painting by Diego Velazquez To the Editor: Recent exhibitions of Diego Velazquez’ (160G1661) work held in New York and Madrid have allowed many people to view the masterpieces of this great artist. More than 300,000 people have visited the exhibition in Madrid. I would like to comment on the trapeziometacarpal osteoarthrosis seen in one of the exhibited pieces, “Old Woman Cooking Eggs,” which is housed at the National Gallery of Scotland in Edinburgh. The painting is of a woman frying eggs in an earthenware vessel while a young boy watches. Her right hand holds a wooden spoon while the left one grasps an egg (Figure 1). Both hands show a marked prominence on the trapeziometacarpal articulation. The more advanced rizarthrosis appears to be on the left hand (1) (Figure 2). This painting is from Velazquez’ early period, when he was living in Seville. It is dated around 1620 (2). Since the painter was not well known at the time, he used his relatives and servants as models. Velazquez was a disciple of the painter Francisco Pacheco and was married to Pacheco’s daughter (3). The old woman cooking eggs was Velazquez’ mother-in-law, who modeled for him in another picture from his early years, “Christ at Marta’s Home,” which is exhibited at the National Gallery of London. At the Museum of Seville, there is exhibited an altar piece where the same woman appears with her husband, Francisco Pacheco (4). In this fine exhibit, there are many examples of pathologic conditions, such as hypotiroideus dwarfism, achondroplasia, drunkenness, and knock-knees. As a rheu- Figure 1. “Old Woman Cooking Eggs,’’ by Diego Velazquez, 1620. (Reproduced with permission of the National Gallery of Scotland in Edinburgh.) LETTERS 128 Use of the pinch strength meter in tender point examination Figure 2. “Old Woman Cooking Eggs” (detail of left hand), by Diego Velazquez, 1620. (Reproduced with permission of the National Gallery of Scotland in Edinburgh.) matologist, I was particularly intrigued by the articular condition depicted in “Old Woman Cooking Eggs.” A. Castillo-Ojugas, PhD Universidad Complutense Madrid, Spain 1. Castillo-Ojugas A: Rheumatology and Spanish art, Seventeenth Congress of the International League Against Rheumatism. Rio de Janeiro, September 17-23, 1989 2. Rardi PM: La obra completa de Velazquez. Barcelona, NoguerRizzoli, 1969 3. Camon Aznar J: Velazquez. Madrid, Espasa Calpe, 1964 4. Gallego J: Catalog0 de la exposicion de Velazquez. Madrid, Museo del Prado, 1990 To the Editor: In a recent report by the Multicenter Criteria Committee for the Classification of Fibromyalgia (Wolfe F, Smythe HA, Yunus MB, Bennett RM, Bombardier C, Goldenberg DL, Tugwell P, Campbell SM, Abeles M, Clark P, Fam AG, Farbor SJ, Fiechtner JJ, Franklin CM, Gatter RA, Hamaty D, Lessard J, Lichtbroun AS, Masi AT, McCain GA, Reynolds WJ, Romano TJ, Russell IJ, Sheon RP: The American College of Rheumatology 1990 criteria for the classification of fibromyalgia: report of the multicenter criteria committee. Arthritis Rheum 33: 160-172, 1990), the committee recommended that tender point examination be done at a pressure of approximately 4 kg (approximately 10 Ib). The pressure level was “determined by having observers palpate the cork end of the dolorimeter and observing the effect required to reach the 4-kg mark.” Not having a dolorimeter available, we found an easier way to determine the effort-by using a pinch strength meter, which is available in virtually every occupational therapy unit. The instrument is placed on the table with one end steadied. The pulp of the thumb is pressed against the upper part of the spring, with the observer noting the pressure achieved (Figure 1). This small instrument can be easily carried in the pocket, and is useful in teaching residents the amount of pressure to apply. Some physicians might want to buy one of these instruments for their own use, but I found it easier to borrow one from a friendly occupational therapist to use during the course of the clinic. It comes with a loop at one end, which is too small to put over the head. It can be looped around a wrist or through a buttonhole or belt, if desired. John Baum, MD University of Rochester Medical Center Rochester. N Y Figure 1. Use of pinch strength meter to determine finger force needed for 4 kg of pressure.