The asymptotic distribution of canonical correlations and vectors in higher-order cointegrated models.

The study of the large-sample distribution of the canonical correlations and variates in cointegrated models is extended from the first-order autoregression model to autoregression of any (finite) order. The cointegrated process considered here is nonstationary in some dimensions and stationary in some other directions, but the first difference (the "error-correction form") is stationary. The asymptotic distribution of the canonical correlations between the first differences and the predictor variables as well as the corresponding canonical variables is obtained under the assumption that the process is Gaussian. The method of analysis is similar to that used for the first-order process.

The asymptotic distribution of canonical correlations and variates in cointegrated models.

The cointegrated model considered here is a nonstationary vector autoregressive process in which some linear functions are stationary and others are random walks. The first difference of the process (the "error-correction form") is stationary. Statistical inference, such as reduced rank regression estimation of the coefficients of the process and tests of hypotheses of dimensionality of the stationary part, involves the canonical correlations between the difference vector and the relevant vector of the past of the process. The asymptotic distributions of the canonical correlations and the canonical vectors under the assumption that the process is Gaussian are found.

Causes of death of persons with developmental disabilities: comparison of institutional and community residents.

Between 1993 and 1995, 1,878 persons transferred from California institutions into the community. By early 1996, 45 had died--significantly more than expected (Strauss, Shavelle, Baumeister, and Anderson, 1998). We report here on the death certificates for this group, using a comparison group of 45 certificates for institutional residents. Thirty-two of the community deaths versus 10 of the institution deaths were "sudden" or "subacute." All of the institution deaths versus 79% of the community deaths were reported to the coroner, and 55% of the institutional deaths were followed by autopsy compared to 33% in the community. Six deaths were due to perforated bowels, 5 of which were in individuals residing in the community.

Long-term survival of children and adolescents after traumatic brain injury.

OBJECTIVE: To obtain information on long-term mortality risk and life expectancy after traumatic brain injury (TBI), to improve planning and for counseling patients and their families. In contrast to the literature for spinal cord injury and other disabilities, there have been few such reports for TBI. DESIGN: Records were reviewed on 946 persons aged 5 to 21 years who had sustained TBI. All were patients who subsequently received disability services in California, 1987 to 1995. RESULTS: The chief predictors of mortality were basic functional skills such as mobility and self-feeding. After the initial high-risk period, mortality risk for TBI was much lower than for similarly functioning persons with cerebral palsy (a comparison group), although after 10 years the two sets of mortality rates had largely converged. For high-functioning persons, life expectancies were only 3 to 5 years shorter than for the general population. By contrast, the remaining life expectancy for those without mobility 6 months after injury was only 15 years.

Mortality in persons with developmental disabilities after transfer into community care.

More than 2,000 persons with developmental disabilities have been transferred from California state institutions into community care in recent years. We investigated whether this has been accompanied by a change in mortality rates, using data on 1,878 clients moved since April 1993. Mortality rates were compared to those expected for comparable persons in institutions. Risk-adjusted mortality rates for movers exceeded institutional rates by 51%, p < .05. After removal of cancer deaths in both groups, this increased to 67%. The effect was largest shortly after the move and in the subjects who had moved most recently. The deinstitutionalization process in California appears to have resulted in a substantial increase in mortality, indicating the need to ensure continuous, consistent, and competent medical care and supervision in the community.

External causes of death among persons with developmental disability: the effect of residential placement.

The authors analyzed death rates from external causes (accidents, injuries, homicides, etc.) for persons with developmental disability in California. There were 520 such deaths during the 1981-1995 study period, based on 733,705 person-years of exposure; this represents all persons who received any services from the state. Compared with the general California population, persons with developmental disability were at lower risk of homicide, suicide, and poisonings (standardized mortality ratios, 0.31-0.68), but higher risk of pedestrian accidents, falls, fires, and, especially, drowning (standardized mortality ratio=6.22). A major focus of the study was comparisons between different residential settings. Persons in semi-independent living had significantly higher risk than did those in their family home or group homes, with homicides rates being three times higher and pedestrian accidents rates being doubled, while persons in institutions had much lower risks with respect to most causes. Of the 28 deaths due to drug and medication overdoses, 79 percent occurred in supported living or small-group homes. Avoidable deaths could be reduced by making direct care staff more aware of the risks and better trained in acute care, along with improved monitoring of special incidents.

Life expectancy of children with cerebral palsy.

Risk factors for mortality of young children with cerebral palsy were studied using a sample of 12,709 children aged 0.5-3.5 years with cerebral palsy who had received services from the State of California between 1980 and 1995. The most powerful prognostic factors for survival were simple functional items: mobility and feeding skills. Once these were known, factors such as severity of mental retardation and presence of quadriplegia contributed relatively little. Children with fair motor and eating skills had good survival prospects, with 90% or more reaching adulthood, but those without such skills had much poorer prospects. Among children who were unable to lift their heads, median survival time was 7 additional years for those who were tube fed (n = 557) and 14 years for those fed entirely by others (n = 997). Although a child's approximate survival chances can be assessed from such functional classifications, we indicate the manner in which additional information on the child's condition can be used to obtain more accurate survival data.

Characterization of a Vascular Wilt of Erythroxylum coca Caused by Fusarium oxysporum f. sp. erythroxyli Forma Specialis Nova.

A new forma specialis of Fusarium oxysporum (F. oxysporum f. sp. erythroxyli) pathogenic to Erythroxylum coca and E. novogranatense is described. The pathogen was isolated from the vascular tissue of diseased plants from an Erythroxylum plantation in Hawaii. This pathogen causes vascular wilt symptoms and death in both E. coca and E. novogranatense plants as soon as 7 weeks after soil infestation. The pathogenicity of seven isolates from the affected field was determined in field and growth-chamber studies. Genetic variation was not detected among the seven Hawaiian isolates, using arbitrarily primed polymerase chain reaction. The seven isolates could be differentiated from a strain isolated from a diseased E. coca plant from South America. All Hawaiian isolates and the South American isolate belonged to a single vegetative compatibility group.

Paternal radiation exposure and leukaemia in offspring: the Ontario case-control study.

OBJECTIVES: To test the hypothesis that there is an association between childhood leukaemia and the occupational exposure of fathers to ionising radiation before a child's conception. DESIGN: Case-control study with eight matched controls per case. SETTING: Regions of Ontario, Canada, with an operating nuclear facility. SUBJECTS: Cases were children (age 0-14) who died from or were diagnosed as having leukaemia from 1950 to 1988 and were born to mothers living in the vicinity of an operating nuclear facility. Controls were identified from birth certificates, matched by date of birth and residence at birth. There were 112 cases and 890 controls. MAIN OUTCOME MEASURES: Paternal radiation exposure was determined by a record linkage to the Canadian National Dose Registry. RESULTS: Six fathers of cases and 53 fathers of controls had had a total whole body dose > 0.0 mSv before the child's conception, resulting in an odds ratio of 0.87 (95% confidence interval 0.32 to 2.34). There was no evidence of an increased leukaemia risk in relation to any exposure period (lifetime or six months or three months before conception) or exposure type (total whole body dose, external whole body dose, or tritium dose), except for radon exposure to uranium miners, which had a large odds ratio that was not significantly different from the null value. CONCLUSIONS: The findings of this study in Ontario did not support the hypothesis that childhood leukaemia is associated with the occupational exposure of fathers to ionising radiation before the child's conception.

Childhood leukemia in the vicinity of Canadian nuclear facilities.

An ecologic study was conducted to determine whether leukemia rates among children born to mothers residing in the vicinity of Ontario (Canada) nuclear facilities differed from the provincial average. Childhood leukemia mortality and incidence ratios for the period 1950 to 1987 were examined for five regions within 25 km of a nuclear facility. The nuclear facilities included a research development facility, a uranium refinery, a uranium mining and milling facility, and two nuclear-power generating stations. Overall, the observed number of leukemia deaths (O = 54) was slightly greater than expected (E = 46.1) during the period when the facilities operated, but the difference was not statistically significant (O/E = 1.17, 95 percent confidence interval [CI] = 0.88-1.53). There was no indication of a birth cohort effect, as the mortality ratios based on place of birth were not significantly greater than the mortality ratios based on place of death. In the analyses of individual facilities, CIs included the null value and were generally wide because of the small observed and expected numbers; however, in the vicinity of the nuclear generating stations, the observed relative excess of leukemia deaths (O = 36, O/E = 1.40) had a lower confidence limit that was close to the null value.

Genetic disorders in children and young adults: a population study.

The data base of an ongoing population-based registry with multiple sources of ascertainment was used to estimate the present population load from genetic disease in more than 1 million consecutive live births. It was found that, before approximately age 25 years, greater than or equal to 53/1,000 live-born individuals can be expected to have diseases with an important genetic component. This total was composed of single-gene disorders (3.6/1,000), consisting of autosomal dominant (1.4/1,000), autosomal recessive (1.7/1,000), and X-linked recessive disorders (0.5/1,000). Chromosomal anomalies accounted for 1.8/1,000, multifactorial disorders (including those present at birth and those of onset before age 25 years) accounted for 46.4/1,000, and cases of genetic etiology in which the precise mechanism was not identified accounted for 1.2/1,000. Previous studies have usually considered all congenital anomalies (ICD 740-759) as part of the genetic load, but only those judged to fit into one of the above categories were included in the present study. Data for congenital anomalies are therefore also presented separately, to facilitate comparison with earlier studies. If all congenital anomalies are considered as part of the genetic load, then greater than or equal to 79/1,000 live-born individuals have been identified as having one or other genetic disorder before approximately age 25 years. These new data represent a better estimate of the genetic load in the population than do previous studies.

Optimal frequency of screening for cervical cancer: a Toronto case-control study.

A retrospective (case-control) study was conducted in Toronto, Canada, between 1973 and 1976 to evaluate the effectiveness of the Papanicolaou smear as a screening procedure for invasive carcinoma of the cervix. In the current study, data from cases of squamous cell cancer of the cervix and controls without hysterectomy were analysed to assess the optimal frequency of cervical screening. The time between the last normal smear and the date of diagnosis was divided into 12-month intervals. Relative protections were then calculated by comparing women who had had one or more normal smears with those who had never been screened. The results show a significant protective effect of screening in women who have had two or more normal smears, when the last was taken within two years of diagnosis. This trend, although not statistically significant, continued even when the last was taken four years before diagnosis, suggesting that screening intervals should not be greater than four years.