Relationship between urinary β2-microglobulin concentration and mortality in a cadmium-polluted area in Japan: A 35-year follow-up study

The relationship between urinary beta(2)-microglobulin (beta(2)-MG) and the risk of all-cause mortality and cause-specific mortality in a cadmium (Cd)-polluted area was investigated in 3139 inhabitants (1404 men and 1735 women) of the Kakehashi River basin in Japan at 35-year follow-up. The subjects had been participants in the 1981-1982 health impact survey that assessed Cd-induced renal dysfunction, as measured by the urinary beta(2)-MG concentration. Hazard ratios were calculated to assess the risk of all-cause and cause-specific mortality according to the urinary beta(2)-MG concentrations. Risk ratios (RRs) were assessed using the Fine and Gray regression model to account for competing risks of cause-specific mortality. The mortality rate was significantly higher in participants with urinary beta(2)-MG concentrations >1000 mu g/g creatinine (Cr) for men and >300 mu g/g Cr for women. In the proportional hazard model, higher urinary beta(2)-MG concentrations were associated with higher risks of circulatory disease, digestive system diseases, and kidney and urinary tract diseases in men and women, and with senility for women. However, when competing risk was accounted for, the RRs were significantly higher only for kidney and urinary tract diseases in men and women (RR for each increment of 1000 mu g/g Cr [95% confidence interval]: 1.02 [1.00-1.04] for men, and 1.01 [1.00-1.02] for women). The long-term prognosis of participants with renal tubular dysfunction was poor, most likely due to kidney and renal tract diseases.

Automated summary

The study found a relationship between urinary beta(2)-microglobulin and the risk of all-cause and cause-specific mortality in a cadmium-polluted area, with higher concentrations of the protein associated with increased risks. Competing risks of cause-specific mortality were taken into account in the analysis, revealing a significant association between higher beta(2)-microglobulin concentrations and kidney and urinary tract diseases in both men and women.