Reproductive longevity and increased life expectancy.

BACKGROUND: Female life expectancy in developed countries has increased by 30 years in the twentieth century. AIM: To determine if there has been an increase in reproductive longevity. METHODS: We analysed age-specific fertility data from birth statistics for the USA, Canada, Japan, France, Sweden, the UK and Australia. RESULTS: Since 1940, birth rates for women aged 35 and over have declined. Among women aged 50 years and older, there has been no increase in births. Fertility rates in 1990 were 0.0 to 0.044 per 1000 women, with total numbers ranging from 0 to 60 births. CONCLUSION: The fertile years have not been prolonged in the cohort of women whose life expectancy has increased so dramatically this century. This suggests that reproductive senescence is tightly controlled and not extended by factors that enhance female longevity. Other physiological mechanisms may also be fixed within narrow age limits.

Night of the sirens: analysis of carbon monoxide-detector experience in suburban Chicago.

STUDY OBJECTIVE: To determine the pattern and environmental causes of carbon monoxide (CO)-detector alarms. METHODS: Data including time, location, detector manufacturer, CO measurements in the home, reported illness, cause, and actions taken were collected between July 15, 1994, and January 26, 1995, on all calls to 17 suburban Chicago fire departments for CO-detector alarms. We used univariate time-series analysis involving joint estimation of model parameters and outlier effects to analyze data and compared data on ambient CO levels from the Illinois Environmental Protection Agency to the number of calls per day. RESULTS: During the study period, 777 calls for sounding CO detectors were made to the fire departments in question. The median number of calls per day was three. Our univariate time series identified 3 days with a significant excess of calls (December 12, 29 calls; December 21, 69; December 22, 128; P < .001). The average ambient CO readings on these days were 0.99, 3.25, and 3.89 ppm, respectively, compared with an overall mean of 8.8 ppm. In-home CO levels among all 828 measurements taken from the 777 domestic calls ranged from 0 to 425 ppm, 0 in 249 (30%), 1 to 10 in 340 (41%), 11 to 50 in 149 (18%), 51 to 100 in 22 (9%), and more than 100 in 11 (1.3%). No measurement was taken in six cases. Cause of alarm was listed as furnace in 25 cases, auto exhaust in 24, stove/oven in 22, poor location of detector in 14, water heater in 11, outside sources in 7, and multiple sources in 7. Other sources accounted for fewer than 1% each. The participating fire departments considered 242 cases (31%) to be false alarms. Cause was not determined in 400 calls (51%). In 37 calls (4.8%), people reported illness. CONCLUSION: Above-average ambient CO levels coincided with a significant increase in the number of calls and may have contributed to the triggering of CO alarms.

Use of the scan statistic to detect temporal clustering of poisonings.

The purpose of this study is to explore the use of the scan test to detect temporal clustering of poison control center data. We applied the scan test to a computerized data set consisting of all cases of carbon monoxide poisoning reported to our Poison Control Center in 1988. Using a time window of three days, the scan test identified three statistically significant temporal clusters. A review of case and climatologic data revealed that two of the clusters were due to family outbreaks and one was due to a sudden cold spell. We conclude that the scan test is a potentially useful surveillance tool which can be easily applied to poison control center data.

The impact of volume on outcome in seriously injured trauma patients: two years' experience of the Chicago Trauma System.

The American College of Surgeons has stated that in considering the development of trauma systems it is important to ensure an appropriate volume of seriously injured patients be seen by each trauma center in order to achieve acceptable mortality rates. Clinical data supporting this recommendation are lacking. An analysis was performed on 1,643 seriously injured trauma patients to determine the relationship between volume and mortality rates. Three separate statistical methods were used: Pearson correlation coefficients, mortality odds ratios, and direct pairwise mortality comparisons. In addition, Tobit analysis was introduced as a method to analyze the relationship between volume and mortality. Mortality rates were adjusted for the confounding variable of serious head injury. Pearson correlation coefficients for volume vs. adjusted mortality was -0.65. Mortality odds ratios comparing the low-volume (less than 140 pts) trauma centers vs. the high-volume (greater than 200 pts) trauma centers was 1.3 for adjusted mortality rates (95% CI = 1.01-1.66; p = 0.04). Categorical analysis showed significantly different mortality rates in the centers before and after adjusting for patient mix. Tobit analysis showed the relationship between volume and mortality to be significant, accounting for 30-40% of the observed variation in mortality rates. In addition, Tobit analysis allowed construction of a model to predict mortality rates, given specific volumes of patients. Our data suggest that an inverse relationship exists between volume and mortality, and support the necessity of configuring trauma systems in a manner that will ensure designated trauma centers will see a high volume of seriously injured patients.

Effects of nonparticipation in trauma center system on emergency department utilization.

The University of Illinois Hospital (UIH) serves an inner-city urban population in one of the highest crime rate districts in Chicago. On May 20, 1986, the city's Level I Trauma ordinance took effect with the University of Illinois Hospital declining to participate. To measure the impact of the ordinance on a nonparticipating hospital, we undertook a retrospective analysis of our trauma patient utilization statistics. Consecutive monthly patient census data of 71 months was compiled with emphasis on patient presenting complaints and related subspecialty evaluation. We observed significant decreases of patients presenting with head injuries, fractures, and animal bites as well as with major trauma, minor trauma, and general surgery hospital admission. The final disposition of the patients arriving by ambulance was consistent with the observed decrease in major traumatic conditions and in minor traumatic conditions. However, the mean number of patient presentations per day (ppd) admitted to regular medical or surgical beds decreased from 2.70 ppd to 2.30 ppd while the mean number of ppd sent home increased from 2.64 ppd to 3.49 ppd. These data suggest that loss of trauma center status designation has a profound effect on utilization of emergency departments not participating in the trauma system. Nonparticipation appears to be associated with a significant decrease in utilization rates for major and minor trauma patients and a significant increase in the number of patients discharged who had arrived by the Chicago Fire Department Paramedic System (CFD). This effect on the emergency department extends to utilization of inpatient services.