EPIDEMIOLOGY OF PRIMITIVE GLOMERULOPATHY IN A FRENCH REGION - VARIATIONS AS FUNCTION OF AGE AND RESEARCH PERIOD

Between January 1st, 1976 and December 31th, 1990, histological diagno sis of primary glomerular diseases (PGD) was made in 480 patients born and living at the time of diagnosis in a region of France comprising 410 664 inhabitants, of whom 390 574 were aged from 10 to 80 years. Th e prevalence of PGD during a 70-year exposure to risk (10-80 years of age) was evaluated to 5.7 in 1000 (7.6 in 1000 males and 3,8 in 1000 f emales). The most common PGD was IgA nephropathy with a prevalence of 1.9 in 1000 (3.3 in 1000 males, 1 in 1000 females). The annual inciden ce of the disease was evaluated separately for 3 conscutive 5-year per iods: period A (1976-80), period B (1981-85), and period C (1986-90). Within each of these 3 periods the number of patients with PGD was 179 , 170 and 131 respectively, and annual incidence was 9.3, 8.8 and 6.7 in 100 000. The incidence of IgA nephropathy remained the same through out the 3 periods: 2.6, 3.1 and 2.5 in 100 000. The incidence of membr anoproliferative glomerulonephritis decreased from 1981 onward (0.9, 0 .5 and 0.15/100 000). Acute streptococcal glomerulonephritis virtually disappeared during periods B and C. Lipoid nephrosis was less frequen t in period C and idiopathic proliferative glomerulonephritis with cre scents slightly increased (0.3, 0.3 and 0.6 in 100 000). There was no significant difference between the 3 periods regarding the incidence o f other PGD. Incidence of IgA nephropathy was 3 to 4-fold higher in th e adult aged from 20 to 60 years than in the elderly. In contrast, mem branous nephropathy was 3 fold more frequent in the elderly than in th e adult. Therefore only some histopathological forms have a different incidence according to age, but the major information furnished by thi s study is that the risk of occurrence of a PGD is similar in the popu lation living in the area, whatever the age group (10-19 years: 6.4/10 (5) inhabitants, 20-39: 7.1/10(5), 40-59: 8.4/10(5), 60-79. 8.4/10(5)) . Finally, we confirm that the most common PGD going to end stage rena l disease was IgA nephropathy, particularly under 60 years of age (0.8 /10(5)). In contrats, membranous nephropathy was a less frequent cause of ESRD (0.2/10(5)).