Purine-Rich Foods and the Risk of Gout in Men
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《新英格兰医药杂志》
To the Editor: Choi et al. (March 11 issue)1 studied diet in relation to gout but did not control for the use of aspirin or diuretics. These agents are used by a very large number of people. They raise uric acid levels, and they cause gout.
J. Lawrence Dohan, M.D.
Marlborough Hospital
Marlborough, MA 01752
References
Choi HK, Atkinson K, Karlson EW, Willett W, Curhan G. Purine-rich foods, dairy and protein intake, and the risk of gout in men. N Engl J Med 2004;350:1093-1103.
To the Editor: The data presented by Choi and colleagues on diet and the risk of gout in men are attractive. Unfortunately, during the 12-year follow-up, the 730 new cases of gout were documented on the basis of the preliminary criteria of the American College of Rheumatology for gout.1 Only 11 percent of patients underwent arthrocentesis, and only 65 percent of those were reported as having monosodium urate crystals in the synovial fluid. Therefore, only 7 percent of patients in this study had evidence of monosodium urate crystals to confirm gouty arthritis. Even when the clinical appearance strongly suggests gout, the diagnosis should be confirmed by needle aspiration.2 Monosodium urate crystals can be observed in over 95 percent of patients who have attacks of acute gouty arthritis.3 Not all podagra is gout, and not all hyperuricemia is gout. Therefore, joint aspiration is of great importance in the diagnosis of acute gouty arthritis.4
Naomi Schlesinger, M.D.
University of Medicine and Dentistry of New Jersey–Robert Wood Johnson Medical School
New Brunswick, NJ 08903
schlesna@umdnj.edu
References
Wallace SL, Robinson H, Masi AT, Decker JL, McCarty DJ, Yu TF. Preliminary criteria for the classification of the acute arthritis of primary gout. Arthritis Rheum 1977;20:895-900.
Lally EV, Zimmerman B, Ho G Jr, Kaplan SR. Urate-mediated inflammation in nodal arthritis: clinical and roentgenographic correlations. Arthritis Rheum 1989;32:86-90.
Reginato AJ, Schumacher HR Jr. Crystal-associated arthropathies. Clin Geriatr Med 1988;4:295-322.
Schlesinger N, Baker DG, Schumacher HR Jr. How well have diagnostic tests and therapies for gout been evaluated? Curr Opin Rheumatol 1999;11:441-445.
The authors reply: In response to Dr. Dohan's letter: when we additionally adjusted for salicylate use in our final multivariate models, the dietary results did not change materially. Low doses of salicylate (75, 150, and 325 mg daily) were shown to increase serum uric acid levels slightly (by 0.27, 0.21, and 0.04 mg per deciliter, respectively).1 However, the effect on the risk of gout of this salicylate-induced increase in the serum uric acid level has not been determined. Our final published multivariate results were already adjusted for the use of diuretics, as described in the Methods section of our article and in the notes to Tables 3, 4, and 5 and the legend to Figure 1.
Although the presence of urate crystals in joint fluid would be diagnostic of gout, as Dr. Schlesinger notes, the sensitivity of this finding would be low, especially in a population study investigating new cases of gout, because arthrocentesis is performed infrequently. Thus, a requirement that the presence of urate crystals in the joint be documented would mean that most cases of gout would be missed. Meanwhile, like other, often-used diagnostic criteria — such as the American College of Rheumatology (ACR) criteria for systemic lupus erythematosus and rheumatoid arthritis — the ACR survey criteria for gout2 provide a diagnostic definition that is appropriate and relevant to this type of study; these criteria have been successfully used in other studies of gout.3,4 The American Rheumatism Association's subcommittee on the classification criteria for gout reported that fulfillment of 6 of the 11 survey criteria had a sensitivity of 84.8 percent and a specificity of 92.7 percent (against pseudogout).2 Our validation study showed a high concordance rate for the diagnosis of gout between those ACR criteria and medical-records review (94 percent). Furthermore, the incidence of gout (fulfilling those ACR criteria) in our cohort closely agreed with the estimated rate among male physicians in the Johns Hopkins Precursor Study.3
One of our secondary end points was gout as defined by the presence of a tophus or the detection of urate crystals on arthrocentesis (identified in 118 men). As we reported, our findings persisted when we restricted the cases to those with tophus or crystal-proven gout. In fact, the magnitudes of the associations tended to increase substantially with the use of this specific definition.
Hyon K. Choi, M.D., Dr.P.H.
Massachusetts General Hospital
Boston, MA 02114
hchoi@partners.org
Gary Curhan, M.D., Sc.D.
Harvard School of Public Health
Boston, MA 02115
References
Caspi D, Lubart E, Graff E, Habot B, Yaron M, Segal R. The effect of mini-dose aspirin on renal function and uric acid handling in elderly patients. Arthritis Rheum 2000;43:103-108.
Wallace SL, Robinson H, Masi AT, Decker JL, McCarty DJ, Yu TF. Preliminary criteria for the classification of the acute arthritis of primary gout. Arthritis Rheum 1977;20:895-900.
Roubenoff R, Klag MJ, Mead LA, Liang KY, Seidler AJ, Hochberg MC. Incidence and risk factors for gout in white men. JAMA 1991;266:3004-3007.
Shadick NA, Kim R, Weiss S, Liang MH, Sparrow D, Hu H. Effect of low level lead exposure on hyperuricemia and gout among middle aged and elderly men: the Normative Aging Study. J Rheumatol 2000;27:1708-1712.
J. Lawrence Dohan, M.D.
Marlborough Hospital
Marlborough, MA 01752
References
Choi HK, Atkinson K, Karlson EW, Willett W, Curhan G. Purine-rich foods, dairy and protein intake, and the risk of gout in men. N Engl J Med 2004;350:1093-1103.
To the Editor: The data presented by Choi and colleagues on diet and the risk of gout in men are attractive. Unfortunately, during the 12-year follow-up, the 730 new cases of gout were documented on the basis of the preliminary criteria of the American College of Rheumatology for gout.1 Only 11 percent of patients underwent arthrocentesis, and only 65 percent of those were reported as having monosodium urate crystals in the synovial fluid. Therefore, only 7 percent of patients in this study had evidence of monosodium urate crystals to confirm gouty arthritis. Even when the clinical appearance strongly suggests gout, the diagnosis should be confirmed by needle aspiration.2 Monosodium urate crystals can be observed in over 95 percent of patients who have attacks of acute gouty arthritis.3 Not all podagra is gout, and not all hyperuricemia is gout. Therefore, joint aspiration is of great importance in the diagnosis of acute gouty arthritis.4
Naomi Schlesinger, M.D.
University of Medicine and Dentistry of New Jersey–Robert Wood Johnson Medical School
New Brunswick, NJ 08903
schlesna@umdnj.edu
References
Wallace SL, Robinson H, Masi AT, Decker JL, McCarty DJ, Yu TF. Preliminary criteria for the classification of the acute arthritis of primary gout. Arthritis Rheum 1977;20:895-900.
Lally EV, Zimmerman B, Ho G Jr, Kaplan SR. Urate-mediated inflammation in nodal arthritis: clinical and roentgenographic correlations. Arthritis Rheum 1989;32:86-90.
Reginato AJ, Schumacher HR Jr. Crystal-associated arthropathies. Clin Geriatr Med 1988;4:295-322.
Schlesinger N, Baker DG, Schumacher HR Jr. How well have diagnostic tests and therapies for gout been evaluated? Curr Opin Rheumatol 1999;11:441-445.
The authors reply: In response to Dr. Dohan's letter: when we additionally adjusted for salicylate use in our final multivariate models, the dietary results did not change materially. Low doses of salicylate (75, 150, and 325 mg daily) were shown to increase serum uric acid levels slightly (by 0.27, 0.21, and 0.04 mg per deciliter, respectively).1 However, the effect on the risk of gout of this salicylate-induced increase in the serum uric acid level has not been determined. Our final published multivariate results were already adjusted for the use of diuretics, as described in the Methods section of our article and in the notes to Tables 3, 4, and 5 and the legend to Figure 1.
Although the presence of urate crystals in joint fluid would be diagnostic of gout, as Dr. Schlesinger notes, the sensitivity of this finding would be low, especially in a population study investigating new cases of gout, because arthrocentesis is performed infrequently. Thus, a requirement that the presence of urate crystals in the joint be documented would mean that most cases of gout would be missed. Meanwhile, like other, often-used diagnostic criteria — such as the American College of Rheumatology (ACR) criteria for systemic lupus erythematosus and rheumatoid arthritis — the ACR survey criteria for gout2 provide a diagnostic definition that is appropriate and relevant to this type of study; these criteria have been successfully used in other studies of gout.3,4 The American Rheumatism Association's subcommittee on the classification criteria for gout reported that fulfillment of 6 of the 11 survey criteria had a sensitivity of 84.8 percent and a specificity of 92.7 percent (against pseudogout).2 Our validation study showed a high concordance rate for the diagnosis of gout between those ACR criteria and medical-records review (94 percent). Furthermore, the incidence of gout (fulfilling those ACR criteria) in our cohort closely agreed with the estimated rate among male physicians in the Johns Hopkins Precursor Study.3
One of our secondary end points was gout as defined by the presence of a tophus or the detection of urate crystals on arthrocentesis (identified in 118 men). As we reported, our findings persisted when we restricted the cases to those with tophus or crystal-proven gout. In fact, the magnitudes of the associations tended to increase substantially with the use of this specific definition.
Hyon K. Choi, M.D., Dr.P.H.
Massachusetts General Hospital
Boston, MA 02114
hchoi@partners.org
Gary Curhan, M.D., Sc.D.
Harvard School of Public Health
Boston, MA 02115
References
Caspi D, Lubart E, Graff E, Habot B, Yaron M, Segal R. The effect of mini-dose aspirin on renal function and uric acid handling in elderly patients. Arthritis Rheum 2000;43:103-108.
Wallace SL, Robinson H, Masi AT, Decker JL, McCarty DJ, Yu TF. Preliminary criteria for the classification of the acute arthritis of primary gout. Arthritis Rheum 1977;20:895-900.
Roubenoff R, Klag MJ, Mead LA, Liang KY, Seidler AJ, Hochberg MC. Incidence and risk factors for gout in white men. JAMA 1991;266:3004-3007.
Shadick NA, Kim R, Weiss S, Liang MH, Sparrow D, Hu H. Effect of low level lead exposure on hyperuricemia and gout among middle aged and elderly men: the Normative Aging Study. J Rheumatol 2000;27:1708-1712.