[Trends in mortality from intractable diseases in Japan, 1972-2004]

In 1972, the Ministry of Health, Labour and Welfare of Japan defined intractable diseases as those with unknown etiology, no established treatment regimens, and severe sequelae of physical, mental and social difficulties. Since then, the Ministry has promoted scientific research on these diseases and offered financial support to those suffering from their effects. The purpose of the present study was to analyze trends in deaths from the diseases in Japan over the period from 1972-2004.

For the selected intractable diseases with 100 deaths or more per year, crude (CDR) and direct age-standardized death rates (ADR) were computed using the national underlying-cause-of-death mortality database of Japan based on International Classification of Diseases. Joinpoint regression analysis was applied to identify significant changes in the trends.

The CDRs in the latest observed year per 1 million persons/year) for males and females were 25.55 and 25.93, respectively, for Parkinson's disease, 5.41 and 6.92 for aplastic anemia, 0.87 and 3.50 for systemic lupus erythematosus, 2.93 and 2.36 for amyloidosis, 1.40 and 1.54 for polyarteritis nodosa, 1.34 and 1.61 for idiopathic thrombocytopenic purpura, and 1.02 and 0.74 for ulcerative colitis. The respective annual percentage changes (APCs) for males and females during the overall period decreased for ulcerative colitis (-5.2% and -7.5%), aplastic anemia (-3.6% and -3.7%), idiopathic thrombocytopenic purpura (-2.1% and -3.0%), and systemic lupus erythematosus (-0.9% and -2.6%), while the APCs increased for amyloidosis (+3.3% and +3.5%), polyarteritis nodosa (+3.2% and +4.0%), and Parkinson's disease (+0.7% in males alone). With the APCs in the latest trend phase, polyarteritis nodosa and Parkinson's disease in females showed appreciable declines; on the other hand, amyloidosis in males demonstrated the significant increase, and ulcerative colitis in males exhibited an apparent leveling off of the decline.

The ADRs for most of the intractable diseases have declined significantly in Japan over the last 3 decades. The decline might be attributed in large part to improved diagnosis and treatment because of the lack of effective primary prevention measures. Support for the affected patients and further research on etiology and radical cure of the diseases must be considered necessary.