An increase in the number of deaths in the United States in the first week of the month--an association with substance abuse and other causes of death.

BACKGROUND AND METHODS There are regular changes in mortality rates, such as increased rates of death from influenza in the winter and from motor vehicle accidents on long holiday weekends. Previous research has shown that among persons with schizophrenia, the rates of cocaine use and hospital admissions increase at the beginning of the month, after the receipt of disability payments. Using computerized data from all death certificates in the United States between 1973 and 1988, we compared the number of deaths in the first week of the month with the number of deaths in the last week of the preceding month. RESULTS The average number of deaths was about 5500 per day, or about 165,000 in a 30-day month. There were 100.9 deaths (95 percent confidence interval, 100.8 to 101.0) in the first week of the month for every 100 deaths in the last week of the preceding month. This was equivalent to about 4320 more deaths in the first week of each month than in the last week of the preceding month in an average year. Between 1983 and 1988, for deaths involving substance abuse and an external cause (such as suicides, accidents, and homicides), there were 114.2 deaths (95 percent confidence interval, 110.5 to 117.9) in the first week of the month for every 100 in the last week of the preceding month. There were significant increases in the number of deaths in the first week of the month for many causes of death, including substance abuse, natural causes, homicides, suicides, and motor vehicle accidents. CONCLUSIONS In the United States, the number of deaths is higher in the first week of the month than in the last week of the preceding month. The increase at the beginning of the month is associated with substance abuse and other causes of death.