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Results for “Multivariate response regression”

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PubMed1995

A survey screen for prediction of apnea.

Questionnaire data from patients presenting at three sleep disorders centers were used to develop and assess a screening tool for sleep apnea based on the reporting of the frequency of various symptoms of sleep apnea and other sleep disorders plus age, body mass index (BMI) and gender. Patients were not specifically referred for suspicion of sleep apnea. Separate factor analyses of survey responses from 658, 193 and 77 respondents from the first, second and third sites, respectively, each yielded four orthogonal factors, one of which accounted for all the questions concerned with the frequency of disordered breathing during sleep. The survey was shown to be reliable in a subset of patients from one of the sites (test-retest correlation = 0.92). Survey data were then compared to a clinical measure of sleep apnea (respiratory disturbance index) obtained from polysomnography. A multivariable apnea risk index including survey responses, age, gender and BMI was estimated using multiple logistic regression in a total sample of 427 respondents from two of the sites. Predictive ability was assessed using receiver operating characteristic (ROC) curves. The area under the ROC curve was 0.79 (p < 0.0001). For BMI alone, it was 0.73, and for an index measuring the self-report of the frequency of apnea symptoms, it was 0.70. The multivariable apnea risk index has potential utility in clinical settings.

Adult↗

PubMed1999

Integrated approach to prediction of cervical intra-epithelial neoplasia status through a case-control study.

A case-control study on cervical intra-epithelial neoplasia (CIN) was carried out on 398 subjects in the state of West Bengal, India. These samples were taken from mass screening programs organized by the authors, maintaining the uniformity of sampling to the extent possible. The cervical smears were tested by the Papanicolaou (PAP) method, following the Bethesda system for reporting of CIN status. Odds ratios and correlation coefficients among different variables, assumed to produce carcinoma of the cervix, show that 6 out of 11 variables, i.e., age, education, socio-economic status, duration of marriage, age at marriage and body surface, are associated with CIN. Multivariate analysis of logistic regression was carried out using BMDP-LR with dichotomized response variables considering CIN (0 and 1) in one group and CIN (2 and 3) in the other group. The outcome of the analysis indicated that age and educational level are 2 contributing factors for CIN. The percentage of correct classification in this analysis has improved to 74.5%, with a probability of 0.90. Polychotomous regression analysis was carried out using BMDP-PR in the next step. This analysis showed that parity was a contributing factor, in addition to age and educational level. These 3 factors provide a predictive model for identifying the high-risk group in a rational way. This approach would restrict screening to approximately 10% of the population. Subsequently, the model has been validated in a confirmatory trial among 85 new cases and was found to work satisfactorily.

Adult↗

PubMed2001

Risk factors for ICU mortality in critically ill patients.

BACKGROUND AND PURPOSE: Advances in critical care medicine have increased the chances of survival for patients with severe illness or trauma. However, such patients consume a large proportion of medical resources. This study sought risk factors for mortality that have potential to be modified among patients treated in medical or surgical intensive care units (ICUs). METHODS: This 6-month prospective observational study was conducted in the medical and surgical ICUs of an 1,800-bed university hospital. All adult patients with an expected ICU stay of 48 hours or more were followed up regularly until discharge from the ICUs, or for 10 weeks during their stay in ICUs. RESULTS: Of 342 patients enrolled, 77 (22.5%) died during a median follow-up period of 5 days (range, 2-70 days). Among a range of variables at the time of ICU entry or developing during stay in ICUs, 17 were associated with higher mortality rate. Multivariate analysis using a logistic regression model demonstrated that the presence of systemic inflammatory response syndrome (SIRS) at the time of ICU entry (adjusted relative risk, ARR, 2.85; 95% confidence interval, CI, 1.16-7.05), Acute Physiological and Chronic Health Evaluation (APACHE) II score on ICU Day 4 (ARR 1.12 with increment of one score; 95% CI 1.01-1.24), Therapeutic Intervention Scoring System (TISS) score on Day 4 (ARR 1.13 with increment of one score; 95% CI 1.05-1.23), parenteral nutrition (ARR 4.97, 95% CI 1.73-14.26), and nosocomial Candida infection (ARR 3.39, 95% CI 1.12-10.23) were independently associated with ICU mortality. CONCLUSIONS: In addition to SIRS and the APACHE II and TISS scores, this study found that nosocomial Candida infection and parenteral nutrition were independently associated with mortality after control for admission conditions, severity of illness scores, and interventions.

Adolescent↗

PubMed2006

Estimation of the benchmark dose by structural equation models.

While epidemiological data typically contain a multivariate response and often also multiple exposure parameters, current methods for safe dose calculations, including the widely used benchmark approach, rely on standard regression techniques. In practice, dose-response modeling and calculation of the exposure limit are often based on the seemingly most sensitive outcome. However, this procedure ignores other available data, is inefficient, and fails to account for multiple testing. Instead, risk assessment could be based on structural equation models, which can accommodate both a multivariate exposure and a multivariate response function. Furthermore, such models will allow for measurement error in the observed variables, which is a requirement for unbiased estimation of the benchmark dose. This methodology is illustrated with the data on neurobehavioral effects in children prenatally exposed to methylmercury, where results based on standard regression models cause an underestimation of the true risk.

Biometry↗

PubMed2003

Inference for a linear regression model with an interval-censored covariate.

Interval-censored observations of a response variable are a common occurrence in medical studies, and usually result when the response is the elapsed time until some event whose occurrence is periodically monitored. In this paper we consider a multivariate regression setting in which the explanatory variable is interval censored. Use of an ad hoc method of analysis for such data, such as taking the midpoint of the interval-censored covariate and applying ordinary least-squares, is not in general valid. We develop a likelihood approach, together with a two-step conditional algorithm, to jointly estimate the regression coefficients as well as the marginal distribution of the covariate. The resulting estimators are asymptotically normal. The performance of the method is assessed via simulations, and illustrated using data from a recent HIV/AIDS clinical trial to assess the association between waiting time between indinavir failure and subsequent viral load at enrolment. Extensions of the procedure to other parametric distributions are discussed.

Adult↗

PubMed2000

Identification and interpretation of clinical and quality of life prognostic factors for survival and response to treatment in first-line chemotherapy in advanced breast cancer.

The aim of the project was to identify clinical and quality of life (QL) factors that together predict survival and response to chemotherapy in advanced breast cancer. Potential prognostic factors were studied in 187 women with baseline QL data from a trial of paclitaxel versus doxorubicin as first-line chemotherapy. Demographic and clinical factors studied were age, performance status, dominant site of disease and preceding disease-free interval (DFI). Factors from the EORTC QLQ-C30 were all function scales, fatigue, nausea/vomiting, pain, dyspnoea, insomnia, loss of appetite and global QL. The proportional hazards regression model with stratification for treatment, and the logistic regression model adjusting for treatment arm were used for univariate and multivariate analyses of survival and response to treatment, respectively. For survival, multiple sites of visceral disease, pain, global QL and fatigue were significant prognostic factors in the univariate analysis. The final multivariate model predicted poor survival with multiple sites of visceral disease (P=0.003), DFI </=2 years (P=0.026) and pain (P=0.003). For response, age, dyspnoea, fatigue and global QL were significant predictive factors in the univariate analysis. The final multivariate model for response selected DFI (P=0.009), multiple sites of visceral disease (P=0.037) and dyspnoea (P=<0.001) using forward selection, but model instability was indicated by the inclusion of fatigue and emotional function in the final model when backward selection was used. In addition to known clinical factors, patient-assessed QL variables appear to be prognostic for survival and response to chemotherapy in women with advanced breast cancer. However, identification of prognostic factors from responses to questionnaires may be unstable, and their reliability and clinical utility should be tested prospectively.

Adolescent↗

PubMed2001

Quality of life and symptoms in a randomized trial of radiotherapy versus deferred treatment of localized prostate carcinoma.

BACKGROUND: Treatment of localized prostate carcinoma (LPC) using radiotherapy (RT) can induce disturbances in a patient's quality of life (QOL) and urinary and intestinal function. Late symptoms and QOL were evaluated in a randomized trial between RT and deferred treatment (DT). METHODS: Quality of life was evaluated with European Organization for Research and Treatment of Cancer's QLQ-C30 (+3) formula. Urinary and intestinal problems were evaluated with a validated symptom specific self-assessment questionnaire, QUFW94. The questionnaires were sent to 108 randomized patients with LPC and to an age-matched control group (n = 68). Mean age was 72 years. Mean total dose was 65 grays (Gy; 62.3-70 Gy). The median follow-up time from randomization was 40.6 months for the RT group and 30.4 months for the DT group. RESULTS: Social functioning was the only QOL scale in which a significant difference was found between the two patient groups and compared with the control group. Multivariate regression analysis showed that hematuria, incontinence, mucus, and planning of daily activities in response to intestinal problems caused this decrease in QOL in the RT group. A significant increase of intestinal problems was observed in the RT versus DT groups regarding mucus, stool leakage, intestinal blood, and planning of daily activity in response to intestinal problems. CONCLUSIONS: The RT patients showed increased levels of minor intestinal side effects compared with the DT patients and the controls, but the RT patients reported no decreased QOL except for decreased social functioning. This could be because this group developed coping skills or because of a low magnitude of side effects to influence the QOL.

Adaptation, Psychological↗

PubMed1989

Predicting local recurrence of carcinoma of the rectum after preoperative radiotherapy and surgery.

A prospective study of prognostic factors has been carried out in a group of 186 patients with tethered rectal carcinomas. Of these, 97 were randomized to surgery alone and 89 to receive preoperative radiotherapy (20 Gy in four fractions). DNA ploidy was determined by flow cytometry. DNA aneuploidy was detected in 60 patients (62 per cent) in the surgery only group, but in only 33 patients (37 per cent) after radiotherapy (P less than 0.01). There was a significant reduction in local recurrence in irradiated patients (P less than 0.0001). DNA diploid tumours were less likely to recur locally. This was more marked in the radiotherapy group (P = 0.01) than in the surgery only group (P = 0.06). After radiotherapy, only the surgeons' assessments of a 'curative' resection and DNA ploidy were independent predictors of local recurrence in multivariate regression analysis, whilst Dukes' classification was not. In conclusion, DNA ploidy may indicate response to radiotherapy and is an important predictor of subsequent local tumour progression.

Combined Modality Therapy↗

PubMed2002

[Patient evaluation of postoperative recovery. An evaluation of the QoR scores in 577 patients].

BACKGROUND: In 1999 Myles and co-workers presented their quality of recovery score (QoR score) as a tool to evaluate postoperative recovery and to measure patient satisfaction. It was developed according to predefined psychological standards and its reliability and validity had been proven in large clinical trials. The aim of this study was to evaluate a German version of the QoR in a heterogeneous group of surgical patients. METHODS: A total of 577 unselected patients completed a modified questionnaire. The response rate and time spent on completing the test were recorded. A stepwise multivariate regression analysis identified factors with significant impact on the QoR score. Other analyses were performed descriptively. RESULTS: Of the patients 83% completed the questionnaire in a median time of 9 h after surgery without assistance. For 75% of these it took 2 min or less. The median QoR score was 15 (10(th)/90(th) percentile: 11/18). Cronbach's p (=0.63) and mean corrected item correlation (=0.32) were used as measures of internal reliability. Factors with impact on the QoR score were: period of time after surgery when performing the test, severity of surgery, sex, general vs local anaesthesia, duration of anaesthesia, and age. CONCLUSIONS: The German translation of the QoR score is easily applicable to a heterogeneous surgical population and thus can be used as a valuable measure of quality of anaesthesia care and patient satisfaction.

Adult↗

PubMed2000

Infectiousness of Mycobacterium tuberculosis in HIV-1-infected patients with tuberculosis: a prospective study.

BACKGROUND: Previous studies concerning the relative infectiousness of HIV-1-positive individuals with pulmonary tuberculosis have produced conflicting results. Thus, we assessed the effect of HIV-1 on the infectiousness of Mycobacterium tuberculosis in a prospective study. METHODS: We organised in Santo Domingo, Dominican Republic, a cohort study of household contacts of HIV-1-positive and HIV-1-negative individuals with newly diagnosed pulmonary tuberculosis. Household contacts were assessed at their houses at baseline and followed up for 14 months for evidence of M tuberculosis infection and tuberculosis with a multi-step tuberculin skin test, anergy skin test, physical examinations, chest radiographs, and sputum smears. FINDINGS: Tuberculin induration of 5 mm or greater was seen in 153 (61%) of 252 household contacts of HIV-1-positive index cases and in 418 (76%) of 551 household contacts of HIV-1-negative index cases (odds ratio 0.49 [95% CI 0.35-0.67], p=0.00001). In multivariate logistic-regression analysis after allowance for between-household variation in tuberculin response, HIV-1 infection of the index case remained inversely associated with the tuberculin response of the household contacts (0.52 [0.29-0.93], p=0.02). When the analysis was restricted to household contacts aged between 2 years and 15 years the adjusted association remained significant (0.37 [0.14-0.98], p=0.04). Among household contacts who had a negative tuberculin skin test at baseline, conversion to tuberculin skin test positivity was less frequent among household contacts of HIV-1-positive index cases (cut-off > or =5 mm: 32/131 [24%] vs 71/204 [35%], p=0.05; cut-off > or =10 mm: 23/153 [15%] vs 55/245 [22%], p=0.07). INTERPRETATION: These data suggest that HIV-1-positive individuals with tuberculosis are less likely than HIV-1-negative individuals with tuberculosis to transmit M tuberculosis to their close contacts. No changes in the current policy regarding tuberculosis contact tracing are needed in the presence of HIV-1.

AIDS-Related Opportunistic Infections↗

PubMed1999

Prostate-specific antigen for prostate cancer screening. Do physician characteristics affect its use?

PURPOSE: Screening for prostate cancer with the prostate-specific antigen (PSA) test remains controversial. This controversy is reflected in a lack of consensus in the medical literature and among professional and policy organizations regarding routine screening by PSA. It is not known how physicians respond when recommendations from experts are inconsistent. METHODS: A questionnaire was mailed to 1369 primary care physicians in active practice in Washington State in 1994. Response rate to the survey was 63%. Chi-square tests and multivariate logistic regression analysis were used to examine the effects of physician characteristics on physicians' self report of use of the PSA test for screening asymptomatic male patients, aged 50 to 80, for prostate cancer. RESULTS: Of the 714 physicians included in the analysis, 68% reported routine use of PSA. Use of PSA varied among physicians on the basis of practice setting, years since medical school graduation, and whether compensation was fee-for-service or salaried. Male physicians trained before 1974 and physicians receiving fee-for-service were significantly more likely than other physicians to recommend screening by PSA. CONCLUSIONS: Results suggest that physicians' personal characteristics such as year of medical school graduation, gender, and mode of reimbursement are related to self-reported PSA use.

Chi-Square Distribution↗

PubMed1999

Association of dietary protein intake and coffee consumption with serum homocysteine concentrations in an older population.

BACKGROUND: Elevated blood concentrations of total homocysteine (tHcy) have been implicated in the pathogenesis of atherosclerotic cardiovascular disease. Previous studies identified suboptimal nutritional status and dietary intake of folate, vitamin B-6, and vitamin B-12 as determinants of elevated tHcy. OBJECTIVE: We identified other nutritional factors associated with tHcy in 260 retired schoolteachers in the Baltimore metropolitan area. DESIGN: We performed observational analyses of baseline and 2-4-mo follow-up data collected in a study designed to test the feasibility of conducting a large-scale clinical trial of vitamin supplements by mail. The study population consisted of 151 women and 109 men with a median age of 64 y. At baseline, each participant completed a food-frequency questionnaire. At follow-up, fasting serum tHcy was measured. RESULTS: In multivariable linear regression and generalized linear models, there was an independent, inverse dose-response relation between dietary protein and In tHcy (P = 0.002) and a positive, significant dose-response relation between coffee consumption and In tHcy (P for trend = 0.01). Other significant predictors of In tHcy were creatinine (positive; P = 0.0001) and prestudy use of supplemental B vitamins (inverse; P = 0.03). In stratified analyses restricted to persons receiving standard multivitamin therapy, the association of 1n tHcy with dietary protein and coffee persisted. CONCLUSIONS: These results support the hypothesis that increased protein intake and decreased coffee consumption may reduce tHcy and potentially prevent atherosclerotic cardiovascular disease and other disease outcomes.

Aged↗

PubMed2006

Prevalence and profile of methamphetamine users in adolescents at a juvenile classification home.

The objective of the present study was to investigate the prevalence and risk factors of methamphetamine use in adolescents at a juvenile classification home. The present subjects were 1362 adolescents (1172 male and 190 female) who had been admitted to the Nagoya Juvenile Classification Home. The participants were divided into two groups, a methamphetamine user group and a control group, based on history of methamphetamine use. The presence of methamphetamine use was analyzed in terms of gender, age, number of admissions, violence (types of crime), history of psychiatric treatment, family history (crime, drug misuse and/or alcohol-related disorder), and experience of being abused by their parents or by the persons who were responsible for raising them. The prevalence of methamphetamine use was 6.8% (93/1362). Multivariate logistic regression analyses indicated that gender (female; odds ratio [OR]: 8.1; 95% confidence interval [CI]: 4.6-14.3), age (OR: 1.8, 95%CI: 1.5-2.1), number of admissions (>2, OR: 2.9, 95%CI: 1.8-4.8), violence (OR: 0.4, 95%CI: 0.2-0.7), history of psychiatric treatment (OR: 8.7, 95%CI: 4.0-19.0), and family history of drug misuse (OR: 4.0, 95%CI: 1.6-9.6) were all significantly associated with methamphetamine use. Approximately 7% of participants used methamphetamine. Female gender was a risk factor. Higher age and multiple admissions suggest the persistency and repetition of delinquency. Methamphetamine users were less violent than control subjects. Psychosocial environment (family history of drug misuse) and psychiatric problems (history of psychiatric treatment) were also related to methamphetamine use.

Adolescent↗

PubMed2002

Hygiene levels in a contemporary population cohort are associated with wheezing and atopic eczema in preschool infants.

BACKGROUND: The hygiene hypothesis states that insufficient exposure to certain infectious agents during childhood increases the risk of developing asthma and atopic diseases. Improvements in hygiene levels may be partly responsible for this decline in exposure. AIMS: To assess whether hygiene levels in infancy are associated with wheeze and/or atopic eczema, independent of a number of possible confounding factors. METHODS: Data were gathered from the Avon Longitudinal Study of Parents and Children (ALSPAC). Parental self completion questionnaires provided symptom data on infant wheeze and atopic eczema at 0-6 months and 30-42 months, respectively. A simple hygiene score was derived using questionnaire responses at 15 months, which ranged from least hygienic to most hygienic. Multivariable logistic regression models analysed the effect of hygiene scores on health outcomes, while adjusting for a number of important confounding variables. RESULTS: Increasing hygiene scores were independently associated with wheezing (OR = 1.04; 95% CI: 1.00 to 1.08) and atopic eczema (OR = 1.04; 95% CI: 1.01 to 1.07) between 30 and 42 months, but not in the first six months. The odds ratio was higher for atopic eczema if the rash was reported to have become sore and oozy (OR = 1.09; 95% CI: 1.02 to 1.16). CONCLUSIONS: High levels of hygiene at 15 months of age were independently associated with wheeze and atopic eczema reported between 30 and 42 months, and there was an increased risk for children with more severe eczema during this period. The importance of hygiene in public health should not be dismissed; however, the creation of a sterile environment through excessive cleanliness may potentially be harmful to the immune system.

Child, Preschool↗

PubMed2003

Correlates of sexual risk behaviors among HIV-positive men who have sex with men.

This study examines correlates of unprotected sexual risk practices of an ethnically diverse sample of HIV-seropositive men who have sex with men (MSM) from the New York City and San Francisco metropolitan areas. Participants completed a self-report survey that assessed sexual risk behaviors and potential correlates. A total of 367 men reported sex with a casual male partner in the previous 3 months. Participants were divided into three groups based on level of HIV-transmission risk with HIV negative or unknown-status partners: no unprotected anal sex (58.9%), unprotected receptive anal sex only (14.2%), and unprotected insertive anal sex (22.6%). Multivariate logistic regression analyses indicated that men reporting unprotected anal insertive sex perceived less responsibility to protect their partners from HIV. Men reporting no unprotected anal sex also reported less use of nitrate inhalants, lower temptation for unsafe sex, and fewer HIV-negative and unknown-status partners. Men reporting unprotected receptive anal sex were less anxious than the other two groups but also reported greater depression than those not reporting unprotected anal sex and greater loneliness than those reporting unprotected anal insertive sex. Implications for interventions with HIV-positive MSM are presented.

Adolescent↗

PubMedDate not supplied

[Recent determination of cholesterolemia in a healthy adult population from Pamplona].

BACKGROUND: The aims of the study were to assess the proportion of the healthy adult population from Pamplona who were aware of their blood cholesterol levels, and to identify factors associated with this awareness. METHODS: A cross-sectional study was implemented with personal interview to 1066 citizens from Pamplona selected by a random routes sampling procedure. The city was stratified in three urban districts according to the socioeconomic status (high, middle, low). The response rate was 91.8%. The crude odds ratios were computed and a multivariable logistic regression model was fitted using awareness of the blood cholesterol level as the dependent variable, and age, sex, socioeconomic status and smoking as independent variables. RESULTS: 71.2% of the sample (95% CI: 68.3-74.0) reported having some cholesterol determination during the last five years. The multivariate analysis disclosed that non-smokers were aware of their cholesterol levels more frequently than smokers (adjusted OR = 1.38; 95% CI 1.0-1.9), determination of cholesterolemia was also less frequent in individuals under 30 years old and in females (adjusted OR in males: 1.5; 95% CI 1.1-2.0). Regarding socioeconomic status, cholesterol measurement was more frequent in middle and high levels with adjusted OR = 3.2; 95% CI 2.2-4.71 and 1.59; 95% CI 1.11-2.27), respectively. CONCLUSIONS: Cholesterol awareness was more frequent in older individuals and among males. It is remarkable that blood cholesterol measurement was less likely in population groups with worse coronary risk profile (lower socioeconomic status, smokers). This study suggests that there is a need for improving the awareness and control of blood cholesterol levels in healthy adults from Pamplona.

Adult↗

PubMed2004

[Preliminary study on outcome assessment system of treatment of stroke].

OBJECTIVE: In order to scientifically reflect the real efficacy of TCM treatment and to preliminarily establish a definitely valid and reliable assessment system of stroke treatment, with multi-dimensional outcome assessment indexes, including efficacy evaluation system of conventional western medicine, syndrome evaluation criteria in TCM and quality of life assessment system. METHODS: An integrative approach of cross-sectional survey and prospective follow-up was adopted. Two hundred and forty-five case-episodes of stroke patients were assessed by determining such parameters as nerve functional deficit scale, grading of total status of living ability, activity of daily living (ADL), TCM stroke criteria of diagnosing-treatment, TCM syndrome related symptoms/signs, Health Survey Questionnaire (Short form 36, SF-36), and index of quality of life (QOL), and their construction and relation were analyzed by such methods as multivariate relation, partial relation, linear regression, factor analysis, Cronbach's alpha coefficients, and the responsiveness estimation. RESULTS: The multi-dimensional assessment system of stroke treatment, containing 57 indexes with clarified constructions and classification, was created, and its validity and reliability confirmed after assessement. Various degrees of relationship were found between different TCM Syndromes and different domains of QOL. CONCLUSION: The assessment system of stroke treatment preliminarily created has satisfied reliability and validity. It could be expected to reflect the real efficacy of TCM treatment more inclusive and accurate. TCM Syndrome indexes are considered to be the factor related to both domains of mental and physical health, particularly with the former, therefore, to improve the TCM Syndrome would imply improvement of the mental health, physical health and QOL of the patients.

Aged↗

PubMed1994

Prior crash and violation records of pilots in commuter and air taxi crashes: a case-control study.

With a case-control design, this study examined the relationships of crash/incident history, violation history, pilot age, flight experience, and recent flight time with the likelihood of being involved in commuter aircraft and air taxi crashes. Cases (n = 725) were pilots who had been involved in commuter aircraft or air taxi crashes during 1983-88, identified from the National Transportation Safety Board aviation crash data base. From the Federal Aviation Administration (FAA) airmen information system, 1,555 pilots were randomly selected as controls. Controls were frequently-matched with cases on medical class and calendar year. Different data bases within the FAA's airmen information system were linked to ascertain information about crash/incident and violation records in the previous 3 years, age, total flight time, and flight time in the prior 6 months. Multivariate logistic regression models were fitted to estimate odds ratios and evaluate dose-response effects, non-linear relationships, and interactions. Cases had significantly higher prevalence rates of prior crash/incident and violation records. The estimated odds ratio of being involved in a commuter aircraft or an air taxi crash was 1.7 (95% confidence interval [CI], 1.3-2.4) for crash/incident history, and 1.6 (95% CI, 1.1-2.2) for violation history. A "dose-response effect" was found with both crash/incident history and violation history, with higher odds ratios for pilots with crashes versus incidents or with more serious violations. Total flight time showed a diminishing protective effect. Either very small or very large recent flight time increased the risk of being involved in a commuter aircraft or an air taxi crash.

Accidents, Aviation↗