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Guohua Li

Publications and source records attributed to Guohua Li.

18 recordsLinked to original sources
PubMed2005

Characteristics of alcohol-related fatal general aviation crashes.

BACKGROUND: The effects of alcohol on piloting performance have been studied extensively. Information describing alcohol-related aviation crashes, however, is scant. METHODS: We developed a data system for fatally injured pilots in Maryland, New Mexico, and North Carolina by linking autopsy data from the state medical examiner offices and crash investigation reports from the National Transportation Safety Board. Alcohol-related crashes are defined as those in which the pilot had a blood alcohol concentration of 20 mg/dL or greater. Differences between alcohol- and non-alcohol-related crashes were assessed with regard to pilot characteristics, crash circumstances, and human factors. RESULTS: The National Transportation Safety Board recorded 313 general aviation crashes fatal to the pilot in the three states between 1985 and 2000. Of these crashes, 255 (81%) were matched successfully with medical examiner records. Alcohol testing results were available for 233 of the fatally injured pilots. Of those tested for alcohol, 25 (11%) had blood alcohol concentrations > or =20 mg/dL (mean=75 +/- 64 mg/dL). The majority of alcohol-related crashes (52%) occurred at night (7p.m. to 6a.m.), compared with 28% of other crashes (P < 0.01). Alcohol-related crashes were significantly more likely than other crashes to have involved continued flight under visual flight rules (VFR) into instrument meteorological conditions (IMC) (32% versus 12%, P < 0.01), and flawed decisions (64% versus 41%, P = 0.03). CONCLUSIONS: Distinctive epidemiological patterns are exhibited in alcohol-related fatal general aviation crashes. Alcohol appears to play a particularly important role in crashes involving flight under VFR into IMC.

Accidents, Aviation↗
PubMed2005

Driving-while-intoxicated history as a risk marker for general aviation pilots.

The Federal Aviation Administration conducts background checking for driving-while-intoxicated (DWI) convictions on all pilots. This study examined the association between DWI history and crash risk in a cohort of 335,672 general aviation pilots. These pilots were followed up from 1994 to 2000 through the aviation crash surveillance system of the National Transportation Safety Board. At baseline, 3.4% of the pilots had a DWI history. DWI history was associated with a 43% increased risk of crash involvement (adjusted relative risk: 1.43; 95% confidence interval: 1.15-1.77). The population-attributable risk fraction for DWI history was estimated as 1.4%. In addition to DWI history, male gender, older age, and inexperience were associated with significantly increased risk of crash involvement. The results of this study support DWI history as a valid risk marker for general aviation pilots. The safety benefit of background checking for DWI history needs to be further evaluated.

Adolescent↗
PubMed2005

Drinking history and risk of fatal injury: comparison among specific injury causes.

The effect of acute alcohol use on injury risk is well documented, but the relationship between drinking history and fatal injury has not been adequately studied. The authors performed a case-control analysis to explore the association between drinking history and specific causes of fatal injury. Cases (n=5549) were persons who died from injury, selected from the 1993 National Mortality Followback Survey (NMFS); controls (n=42,698) were a representative sample of the general population, selected from the 1992 National Longitudinal Alcohol Epidemiologic Survey (NLAES). Current drinkers comprised 59% of the cases compared with 44% of the controls. After adjustment for age, sex, race/ethnicity, education, marital status, employment, and drug use, the odds ratio (OR) of dying from drowning for current drinkers was 3.48 (95% confidence interval (CI)=1.94, 6.25), the highest among all causes of injury studied. The lowest adjusted odds ratio associated with current drinking was for falls (OR=1.38; 95% CI=1.05, 1.82). Being a current drinker increased the risk of dying from suicide more for females (OR=4.04; 95% CI=1.64, 9.93) than for males (OR=1.45; 95% CI=1.20, 1.74). The authors conclude that drinking history is associated with a significantly increased risk of all types of fatal injury.

Adolescent↗
PubMed2004

Mortality in epilepsy: driving fatalities vs other causes of death in patients with epilepsy.

OBJECTIVES: To estimate the risk to public safety posed by drivers with epilepsy, the authors compared annual totals and disease-specific risk for fatal crashes associated with seizures and other medical conditions. They compared individual risks for fatal crashes due to seizures and other causes of mortality in patients with epilepsy. METHODS: The authors analyzed Multiple-Cause of Mortality data files from death certificates provided by the National Center for Health Statistics (NCHS) for the years 1995-97. They analyzed International Classification of Diseases-9 codes for underlying causes of death and other major conditions and determined disease-specific rates of fatal crashes associated with seizures and other medical conditions. RESULTS: An average of 44,027 US drivers died annually as a result of motor vehicle crashes during 1995-97; however, only 86 (0.2%, range 82 to 97) of these deaths were associated with seizures in mortality reports. The incidence rate of fatal crashes for patients with seizures was 2.3 times the rate for patients with cardiovascular and hypertensive diseases and 4.6 times the rate for patients with diabetes. The proportionate mortality ratio for motor vehicle crashes in patients with seizures was low (0.2); most patients with epilepsy died of common cardiovascular and systemic disorders. CONCLUSION: Fatal driver crashes due to seizures are uncommon. This finding supports the current public policy of permitting patients whose seizures are controlled to drive.

Accidents, Traffic↗
PubMed2004

Separation, identification of uremic middle molecules, and preliminary study on their toxicity.

BACKGROUND: Compounds accumulating in uremic serum with molecular mass from 300 to 5000 Da are called uremic middle molecules (UMMs). In our previous work, two UMM fractions A and B were obtained from uremic sera, urine, and normal urine by gel permeation chromatography (GPC), and six UMMs from subfraction A3 of uremic plasma and normal urine were purified and characterized. METHODS: Urine and serum samples from uremic patients and healthy subjects were isolated by GPC, ion exchange chromatography (IEC), and reversed-phase high-performance liquid chromatography (RP-HPLC). Moreover, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) were used to characterize the compounds. The effects of subfraction A3 on renal function were studied in rabbit models with chronic renal failure (CRF). RESULTS: A compound with molecular weight 1007.94 in subfraction A3 was determined to be an octapeptide by mass spectrometry, with an amino acid sequence of Val-Val-Arg-Gly-Cys-Thr-Trp-Trp. Two CRF rabbits injected with A3 died in 5 days, while the other two CRF rabbits (no injection) survived a few days. By multistep chromatography and MALDI-TOF MS, another 11 endogenous compounds were found not only in the subfraction B9 of uremic sera but also in that of normal urine. CONCLUSION: Seventeen endogenous middle molecular compounds were found in fractions A and B of uremic plasma and normal urine, among them an octapeptide with M(W) 1007.94 in subfraction A3. Preliminary experimental results on rabbits indicate that subfraction A3 could accelerate the death of rabbits with CRF.

Amino Acid Sequence↗
PubMed2003

Age, flight experience, and risk of crash involvement in a cohort of professional pilots.

Federal aviation regulations prohibit airline pilots from flying beyond the age of 60 years. However, the relation between pilot age and flight safety has not been rigorously assessed using empirical data. From 1987 to 1997, the authors followed a cohort of 3,306 commuter air carrier and air taxi pilots who were aged 45-54 years in 1987. During the follow-up period, the pilots accumulated a total of 12.9 million flight hours and 66 aviation crashes, yielding a rate of 5.1 crashes per million pilot flight hours. Crash risk remained fairly stable as the pilots aged from their late forties to their late fifties. Flight experience, as measured by total flight time at baseline, showed a significant protective effect against the risk of crash involvement. With adjustment for age, pilots who had 5,000-9,999 hours of total flight time at baseline had a 57% lower risk of a crash than their less experienced counterparts (relative risk = 0.43, 95% confidence interval: 0.21, 0.87). The protective effect of flight experience leveled off after total flight time reached 10,000 hours. The lack of an association between pilot age and crash risk may reflect a strong "healthy worker effect" stemming from the rigorous medical standards and periodic physical examinations required for professional pilots.

Accident Proneness↗
PubMed2003

Fragility versus excessive crash involvement as determinants of high death rates per vehicle-mile of travel among older drivers.

Using multiple national data systems, the roles of fragility (susceptibility to injury) versus excessive crash involvement in the increased fatality risk of older drivers per vehicle-mile of travel (VMT) were estimated. For each age and gender group, deaths per driver involved in a crash (a marker of fragility) and drivers involved in crashes per VMT (a marker of excessive crash involvement) were computed. Compared with drivers ages 30-59, those younger than 20 and those 75 or older both had much higher driver death rates per VMT. The highest death rates per mile driven, 13-fold increases, were observed among drivers age 80 or older, who also had the highest death rates per crash. Fragility began to increase at ages 60-64 and increased steadily with advancing age, accounting for about 60-95% of the excess death rates per VMT in older drivers, depending on age group and gender. Among older drivers, marked excesses in crash involvement did not begin until age 75, but explained no more than about 30-45% of the elevated risk in this group of drivers; excessive crashes explained less of the risk among drivers ages 60-74. In contrast, crash over-involvement was the major factor contributing to the high risk of death among drivers younger than 20, accounting for more than 95% of their elevated death rates per VMT. Although both fragility and crash over-involvement contributed to the excess death rates among older drivers per VMT, fragility appeared to be of over-riding importance. These findings suggest that measures to improve the protection of older vehicle occupants in crashes should be vigorously pursued.

Accidents, Traffic↗
PubMed2003

Relative risk of injury and death in ambulances and other emergency vehicles.

This study addresses of the impacts of emergency vehicle (ambulances, police cars and fire trucks) occupant seating position, restraint use and vehicle response status on injuries and fatalities. Multi-way frequency and ordinal logistic regression analyses were performed on two large national databases, the National Highway Traffic Safety Administration's Fatality Analysis Reporting System (FARS) and the General Estimates System (GES). One model estimated the relative risk ratios for different levels of injury severity to occupants traveling in ambulances. Restrained ambulance occupants involved in a crash were significantly less likely to be killed or seriously injured than unrestrained occupants. Ambulance rear occupants were significantly more likely to be killed than front-seat occupants. Ambulance occupants traveling non-emergency were more likely than occupants traveling emergency to be killed or severely injured. Unrestrained ambulance occupants, occupants riding in the patient compartment and especially unrestrained occupants riding in the patient compartment were at substantially increased risk of injury and death when involved in a crash. A second model incorporated police cars and fire trucks. In the combined ambulance-fire truck-police car model, the likelihood of an occupant fatality for those involved in a crash was higher for routine responses. Relative to police cars and fire trucks, ambulances experienced the highest percentage of fatal crashes where occupants are killed and the highest percentage of crashes where occupants are injured. Lack of restraint use and/or responding with 'lights and siren' characterized the vast majority of fatalities among fire truck occupants. A third model incorporated non-special use van and passenger car occupants, which otherwise replicated the second model. Our findings suggest that ambulance crewmembers riding in the back and firefighters in any seating position, should be restrained whenever feasible. Family members accompanying ambulance patients should ride in the front-seat of the ambulance.

Accidents, Traffic↗
PubMed2003

Mortality risk in a birth cohort of commuter air carrier and air taxi pilots.

Commuter and air taxi pilots have higher work-related death rates than most other occupational groups. In this longitudinal study, the authors examined the mortality in a cohort of 3263 commuter and air taxi pilots. With adjustment for age, proportional hazards modeling revealed that termination or downgrading of medical certificates during the 11-year follow-up was associated with a significantly increased risk of overall mortality (relative risk, 2.32; 95% confidence interval [CI] = 1.43-3.77). Relative to the general population with similar demographic characteristics, commuter air carrier and air taxi pilots had significantly lower overall mortality (standard mortality ratio [SMR], 0.36; 95% CI = 0.32-0.41) and mortality from cardiovascular diseases (SMR, 0.18, 95% CI = 0.15-0.22), but considerably higher mortality from aviation crashes (SMR, 128.88; 95% CI = 6.35-2624.36). The results indicate that the current medical certification system is effective in maintaining a healthy pilot workforce.

Accident Proneness↗
PubMed2003

Neighborhood characteristics and emergency department utilization.

OBJECTIVES: Neighborhood environments have been linked to the prevalence and incidence rates of a variety of diseases and injuries. This study assessed the relations between neighborhood demographic and socioeconomic characteristics and emergency department (ED) utilization. METHODS: Billing data for the calendar year 2000 for adult patients residing within a one-mile radius of the study ED were geo-coded based on home addresses and merged with neighborhood data from the U.S. Census Bureau. Annual ED visit rates per 100 population were computed for each census block within the study area and analyzed in relation to neighborhood characteristics. RESULTS: The study area consisted of 714 census blocks and 42,278 adult residents, with a total of 16,427 visits to the study ED. Annual ED visit rates increased from 17 visits per 100 population for neighborhoods where less than 50% of the population were African American to 51 visits per 100 population for neighborhoods where all residents were African American (p < 0.001). Annual ED visit rates decreased from 53% for neighborhoods where <20% of housing units were owner-occupied to 27% for neighborhoods with >45% owner-occupied housing units (p < 0.001). Multivariate linear regression modeling revealed that proportions of African American residents and owner-occupied housing units were significantly associated with ED utilization, independent of age and gender compositions and the distance between residence and the study ED. CONCLUSIONS: Even within a small geographic area, ED utilization may vary greatly by neighborhood characteristics. Neighborhood racial composition and housing tenure are independent predictors of ED visit rates in this urban community.

Adult↗
PubMed2003

Secular trends in adolescent never smoking from 1990 to 1999 in California: an age-period-cohort analysis.

OBJECTIVES: We analyzed age, time period, and cohort effects on trends in adolescent cigarette smoking in California from 1990 to 1999. METHODS: Data from subjects aged 12 to 17 years (n = 26 536; 50.4% male) from the California Tobacco Survey and the California Youth Tobacco Survey were analyzed, and never smokers were used as the outcome measure. RESULTS: The proportion of never smokers increased from 60% for males and 66% for females in 1990 to around 70% for both sexes in 1999. Respondents were more likely to be never smokers if born in 1978 or later (i.e., aged 12 years or younger in 1990, when most tobacco control programs started in California). CONCLUSIONS: The statewide antitobacco programs prevented adolescents from starting to smoke, primarily through a cohort effect.

Adolescent↗
PubMed2002

Exploratory spatial analysis of pilot fatality rates in general aviation crashes using geographic information systems.

Geographic information systems and exploratory spatial analysis were used to describe the geographic characteristics of pilot fatality rates in 1983-1998 general aviation crashes within the continental United States. The authors plotted crash sites on a digital map; rates were computed at regular grid intersections and then interpolated by using geographic information systems. A test for significance was performed by using Monte Carlo simulations. Further analysis compared low-, medium-, and high-rate areas in relation to pilot characteristics, aircraft type, and crash circumstance. Of the 14,051 general aviation crashes studied, 31% were fatal. Seventy-four geographic areas were categorized as having low fatality rates and 53 as having high fatality rates. High-fatality-rate areas tended to be mountainous, such as the Rocky Mountains and the Appalachian region, whereas low-rate areas were relatively flat, such as the Great Plains. Further analysis comparing low-, medium-, and high-fatality-rate areas revealed that crashes in high-fatality-rate areas were more likely than crashes in other areas to have occurred under instrument meteorologic conditions and to involve aircraft fire. This study demonstrates that geographic information systems are a valuable tool for injury prevention and aviation safety research.

Accidents, Aviation↗
PubMed2002

Fatal crashes among older drivers: decomposition of rates into contributing factors.

This study selected US drivers aged 55 years or older who were involved in fatal crashes in 1990 and 1995 and explored factors that influenced their fatal crash involvement rate. The fatal crash involvement rate (risk of being involved in a fatal crash) can be thought of as the product of the crash fatality rate (risk of dying given a crash), the crash incidence density (risk of crash), and the exposure prevalence (amount of driving). Fatal crash involvement rates increased with age. The relative contributions of the crash incidence densities and exposure prevalences were greater than that of the crash fatality rates. The decomposition methodology was shown to be a useful method for investigating the potential benefit of crash prevention interventions aimed at different components of the fatal crash involvement rate.

Accidents, Traffic↗
PubMed2002

Human factors in aviation crashes involving older pilots.

BACKGROUND: Pilot errors are recognized as a contributing factor in as many as 80% of aviation crashes. Experimental studies using flight simulators indicate that due to decreased working memory capacity, older pilots are outperformed by their younger counterparts in communication tasks and flight summary scores. OBJECTIVE: This study examines age-related differences in crash circumstances and pilot errors in a sample of pilots who flew commuter aircraft or air taxis and who were involved in airplane or helicopter crashes. METHODS: A historical cohort of 3306 pilots who in 1987 flew commuter aircraft or air taxis and were 45-54 yr of age was constructed using the Federal Aviation Administration's airmen information system. Crash records of the study subjects for the years 1983-1997 were obtained from the National Transportation Safety Board (NTSB) by matching name and date of birth. NTSB's investigation reports were reviewed to identify pilot errors and other contributing factors. Comparisons of crash circumstances and human factors were made between pilots aged 40-49 yr and pilots aged 50-63 yr. RESULTS: A total of 165 crash records were studied, with 52% of these crashes involving pilots aged 50-63 yr. Crash circumstances, such as time and location of crash, type and phase of flight, and weather conditions, were similar between the two age groups. Pilot error was a contributing factor in 73% of the crashes involving younger pilots and in 69% of the crashes involving older pilots (p = 0.50). Age-related differences in the pattern of pilot errors were statistically insignificant. Overall, 23% of pilot errors were attributable to inattentiveness, 20% to flawed decisions, 18% to mishandled aircraft kinetics, and 18% to mishandled wind/runway conditions. CONCLUSIONS: Neither crash circumstances nor the prevalence and patterns of pilot errors appear to change significantly as age increases from the 40s to the 50s and early 60s.

Accidents, Aviation↗
PubMed2002

Self-rated changes in cognition and piloting skills: a comparison of younger and older airline pilots.

BACKGROUND: The relationship of chronological age to self-rated changes in cognition has been studied extensively. However, the relationship of these changes to age-related changes in piloting skills is not well understood. OBJECTIVE: This study aims to determine whether airline pilots report age-related changes in cognitive abilities, and whether these changes are related to self-rated changes in piloting skills. METHODS: A total of 1310 airline pilots (28-59 yr, mean age = 45.5 yr; mean total flight time = 11,992 h) currently employed by a major U.S. commercial air carrier participated in the study. A 13-item Aviation Experience Survey (AES) was completed by each pilot, using 5-point Likert ratings and yes/no responses comparing current cognitive abilities (e.g., concentration, reaction speed) and piloting skills (e.g., piloting in adverse weather, decision making while flying) with those of 10 yr ago. RESULTS: Cognitive abilities and piloting skills were more likely to be rated as "better' or "much better" than 10 yr ago by pilots age 39 or under than by pilots in their 40s and 50s, who were more likely to rate their abilities and skills as "the same." Fewer than 20% of pilots in any age group rated their cognitive abilities or piloting skills as "worse" or "much worse" than 10 yr ago. Pilots who reported more anxiety or stress while flying reported more negative changes in abilities, skills, and health status regardless of age. CONCLUSIONS: Self-ratings of cognition and piloting skills vary by age, but older pilots are not more likely to report negative changes in their abilities and skills than younger pilots. Further research is needed to verify whether these self-appraisals reflect true changes in skills over time.

Adult↗
PubMed2002

Geographic patterns of pilot fatality rates in commuter and air taxi crashes.

BACKGROUND: Geographic information systems are widely used in studies of diseases. However, their value for aviation safety research has not been adequately explored. PURPOSE: This study examined the geographic patterns of pilot fatality rates in commuter and air taxi operations. METHODS: Crash data recorded by the National Transportation Safety Board under FAR Part 135 were used to create a digital map of all crash sites in the continental United States between 1983 and 1998. Fatality rates in crashes were calculated and then interpolated to create a contoured map of rates. A test of significance was performed using Monte Carlo simulations. High-, medium-, and low-rate areas were then compared for pilot characteristics, airplane characteristics, and crash circumstance. RESULTS: Of the 1094 commuter and air taxi crashes studied, 25% resulted in a pilot fatality. A large geographic area with a pilot fatality rate of > or = 36% extended through portions of Michigan, Indiana, and Illinois. A relatively low fatality rate (< 15%) prevailed over an area extending from Texas to northwest Georgia. Crashes in high-rate areas were significantly more likely than crashes elsewhere to have occurred at night and during instrument meteorological conditions. CONCLUSION: The geographic analysis revealed a distinctive pattern of pilot fatality rates from Part 135 crashes. Factors underlying the geographic pattern should be investigated, with particular attention to the great geographic variability of terrain and weather phenomena between the north and south regions of the United States.

Accidents, Aviation↗
PubMed2002

[Experimental study on effect of recombined decoction on mumps virus].

OBJECTIVE: To evaluate possible inactivating effect of recombined decoction in on mumps virus. METHODS: By adopting tissue cell culturing technology, a group of viruses including the mumps virus, herpes simplex virus (type I, II), rubella virus, cytomegalovirus (CMV), herpes zoster virus, influenza virus, parainfluenza virus, adeno viruses, respiratory syneytial virus (RSV) were cultured. The cells infected with the viruses were treated with the decoction. RESULTS: The decoction showed remarkable inhibitory and killing effects on the mumps virus while had no obvious inhibitory and killing effects on host's cells, herpes simplex virus (type I, II), rubella virus, cytomegalovirus (CMV), herpes zoster virus, influenza virus, parainfluenza virus, adeno viruses, respiratory syneytial virus (RSV). CONCLUSIONS: The decoction had obvious inhibitory and killing effects on mumps virus during single layer cells culture.

Cells, Cultured↗