A long-term prospective controlled study of analgesic abuse in Belgium.

In 1991, Dubach et al clearly demonstrated an increased risk of renal morbidity and mortality after phenacetin abuse in middle aged working women. We investigated the renal effects of the abuse of several kinds of analgesics in abusers of different sex and age categories. A cohort of 200 active analgesic abusers (age range 21 to 86 years) and 200 matched controls was followed for seven years (1984 to 1992). Subjects were visited at home once a year for a short interview and a medical examination. Renal function showed a significant decrease over time in controls as well as in abusers (P < 0.001). The decrease was, however, significantly more pronounced in abusers (P < 0.001). The development of a decreased renal function was observed in 12 abusers and 2 controls resulting in a relative risk of 6.1 (95% CI: 1.4 to 25.9). Subjects showing a decreased renal function underwent a diagnostic investigation. Using validated diagnostic criteria, analgesic nephropathy could be established in 6 out of the 10 abusers who had a diagnostic workup, in the absence of any other form of renal disease.