Machine learning and statistical prediction of fastball velocity with biomechanical predictors.

In recent years, one of the most important factors for success among baseball pitchers is fastball velocity. The purpose of this study was to (1) to develop statistical and machine learning models of fastball velocity, (2) to identify the strongest predictors of fastball velocity, and (3) to compare the models' prediction performances. Three dimensional biomechanical analyses were performed on high school (n = 165) and college (n = 62) baseball pitchers. A total of 16 kinetic and kinematic predictors from the entire pitching sequence were included in regression and machine learning models. All models were internally validated through ten-fold cross-validation. Model performance was evaluated through root mean square error (RMSE) and calibration with 95% confidence intervals. Gradient boosting machines demonstrated the best prediction performance [RMSE: 0.34; Calibration: 1.00 (95% CI: 0.999, 1.001)], while regression demonstrated the greatest prediction error [RMSE: 2.49; Calibration: 1.00 (95% CI: 0.85, 1.15)]. Maximum elbow extension velocity (relative influence: 19.3%), maximum humeral rotation velocity (9.6%), maximum lead leg ground reaction force resultant (9.1%), trunk forward flexion at release (7.9%), time difference of maximum pelvis rotation velocity and maximum trunk rotation velocity (7.8%) demonstrated the greatest influence on pitch velocity. Gradient boosting machines demonstrated better calibration and reduced RMSE compared to regression. The influence of lead leg ground reaction force resultant and trunk and arm kinematics on pitch velocity demonstrates the interdependent relationship of the entire kinetic chain during the pitching motion. Coaches, players, and performance professionals should focus on the identified metrics when designing pitch velocity improvement programs.

Incompatible kidney donor candidates' willingness to participate in donor-exchange and non-directed donation.

Although paired donation, list donation and non-directed donation allow more recipients to receive living donor transplants, policy makers do not know how willing incompatible potential donors are to participate. We surveyed 174 potential donors ruled out for ABO-incompatibility or positive cross-match about their participation willingness. They were more willing to participate in paired donation as compared to list donation where the recipient receives the next deceased donor kidney (63.8% vs. 37.9%, p < 0.001) or non-directed donation (63.8% vs. 12.1%, p < 0.001). Their list donation willingness was greater when their intended recipients moved to the top versus the top 20% of the waiting list (37.9% vs. 19.0%, p < 0.001). Multivariate logistic regression modeling revealed that potential donors' empathy, education level, relationship with their intended recipient and the length of time their intended recipient was on dialysis also affected willingness. For paired donation, close family members of their intended recipient (odds ratio (OR) = 3.01, confidence intervals (CI) = 1.29, 7.02), with high levels of empathy (OR = 2.68, CI = 1.16, 6.21) and less than a college education (OR = 2.67, CI = 1.08, 6.61) were more willing to participate compared to other donors. Extrapolating these levels of willingness nationally, a 1-11% increase in living donation rates yearly (84-711 more transplants) may be possible if donor-exchange programs were available nationwide.

Patient satisfaction measurement strategies: a comparison of phone and mail methods.

BACKGROUND: In 1998 the BJC Health System (St Louis) made the decision to migrate its patient satisfaction measurement system from a mail-out/mail-back method to a phone interview method. Out of concern that results obtained by phone would not be comparable with the 4 years of mail-based data, a controlled study was undertaken to directly compare mail and phone responses and to evaluate response rates, patient sample demographics, and patient satisfaction ratings. METHODS: Mail and phone responses obtained from parallel random samples selected from inpatient, outpatient test/treatment, outpatient surgery, and emergency service patient populations were compared. Patients were randomly selected to receive a standardized satisfaction survey by either phone or mail 10 to 14 days postdischarge. RESULTS: Significantly higher response rates were obtained by telephone then via the mail-based method for all four samples. After adjusting for demographic differences, numerous significant differences in mean scores as well as percentages of excellent and fair or poor responses were observed, and more positive ratings were obtained by phone. DISCUSSION: Crude comparisons of satisfaction scores between organizations using phone and mail-based responses may lead to erroneous conclusions about consumer-perceived quality. Organizations that use mixed-mode surveys should conduct careful side-by-side studies of the methods used on the survey of interest and then establish a correction formula to adjust the results for the measurement biases.

Outcomes of the Learn, Share & Live breast cancer education program for older urban women.

OBJECTIVES: This study assessed whether the Learn, Share & Live breast cancer education program resulted in favorable, replicable, and sustainable outcomes. METHODS: The program was implemented at index (year 1) and replication (year 2) sites. Baseline interviews (year 1; n = 240) and 2 follow-up telephone interviews (years 2 and 3; n = 337 and 323) were used to assess postintervention changes. RESULTS: From baseline to year 2, mammography adherence and stage of adoption improved at the index site relative to the replication site. Knowledge scores and percentages of respondents reporting that a friend had spoken with them about mammography improved significantly. Improvements were sustained through year 3 (2 years postintervention). In year 3, replication participants showed improvements in regard to knowledge and perceived mammography benefits, and there was a trend toward increased adherence. Site differences in postintervention adherence may have stemmed from respective choices of follow-up activities. CONCLUSIONS: The study outcomes affirm the impact of Learn, Share & Live, indicating a replicated and sustained program effect. Future studies should continue longer follow-up and explore the importance of providing mammography opportunities along with education.

The impact of sociodemographics, comorbidity and symptom recency on health-related quality of life in alcoholics.

OBJECTIVE: To obtain estimates of the relationship between alcoholism and health-related quality of life (HRQL) in twin pairs discordant for alcohol dependence. METHOD: In 1995, 1,258 male-male twin pair members of the Vietnam Era Twin Registry (total Registry N = 7.375 pairs) were administered a modified Medical Outcomes Study 36 Item Short Form (SF-36) and the Diagnostic Interview Schedule (DIS) to obtain measures of HRQL and a DSM-III-R criteria lifetime diagnosis of alcohol dependence. Mean within pair differences on eight separate SF-36 subscales were calculated for 436 remitted (no alcohol symptoms in the past 5 years) alcohol-dependent discordant twin pairs and for 194 recent (at least one alcohol symptom in the past 5 years) alcohol-dependent discordant pairs before and after adjustment for covariates. Covariates included lifetime physical illness, lifetime psychiatric disorders, lifetime drug dependence, lifetime nicotine dependence, current marital status, current income and severity. RESULTS: In the unadjusted analysis remitted alcoholic twins compared to their nonalcoholic co-twins reported significantly lower mean scores for six of eight SF-36 subscales. Recent alcoholic twins, compared to their nonalcoholic co-twins, reported significantly lower mean scores for all of the SF-36 subscales. However, after simultaneous adjustment for all covariates, no SF-36 subscale mean, except "vitality" among recent alcoholic twins, was significantly different between alcoholic twins and their nonalcoholic co-twins. CONCLUSIONS: Differences in HRQL between alcoholic and nonalcoholic co-twins is due to covariation from physical and psychiatric problems, drug and nicotine dependence, marital status, income and severity.

Sociodemographic and health status characteristics with prostate cancer screening in a national cohort of middle-aged male veterans.

OBJECTIVES: To characterize variables associated with obtaining prostate cancer screening in a nonclinical, nationally distributed, middle-aged male population. METHODS: Telephone interviews were administered to 2652 individual members of the Vietnam Era Twin Registry in 1992 and 1995. Dependent variables were self-report measures of having had a digital rectal examination (DRE) and/or a prostate-specific antigen (PSA) test in the past 5 years. Independent variables were current measures of age, household income, education, race, insurance, source of care, and lifetime measures of physical condition, psychiatric illness, and alcohol and nicotine dependence. RESULTS: Thirty-five percent of the sample reported having had a PSA and DRE within the past 5 years. Prevalence of obtaining either a PSA or DRE varied with age, income, education, and race. Subjects with a regular source of care, a regular physician, and health insurance reported higher rates of having had a DRE or PSA and DRE. Persons with a physical or psychiatric illness reported more screening. A multiple regression model revealed that having a regular source of care, having a regular physician, physical illness, psychiatric illness, minority status, higher income, and age predicted having had some form of screening. CONCLUSIONS: A substantial portion of middle-aged men have had both a PSA and DRE performed at least once in the preceding 5 years. It may be possible to further improve prostate cancer screening participation by directing educational programs at men who are not in contact with the healthcare system. If the PSA and DRE screening guidelines that are finally adopted discourage screening among low-risk men younger than age 50, educational programs that emphasize age screening criteria may be warranted.

Prevalence changes in modifiable cardiovascular disease risk factors in three Missouri regions, 1990-1996.

OBJECTIVES: To determine the prevalence and prevalence trend of modifiable cardiovascular disease (CVD) risk factors among African Americans and whites/others from 1990-1996. We also examined differential changes between African Americans and whites/others during the same time period. METHODS: This study used data from two special Behavioral Risk Factor Surveillance System (BRFSS) based surveys in 1990 (N = 3,000+) and one in 1996 (N = 2,095) that targeted two metropolitan and one rural region in Missouri with substantial minority populations. Risk factors included physical inactivity, obesity, hypertension, unmonitored cholesterol and smoking. The percent change in prevalence estimates and corresponding confidence intervals between survey years were calculated for each of the above risk factors. RESULTS: When compared with Missouri BRFSS data, overall prevalence of smoking, obesity, hypertension and unmonitored cholesterol was higher in the three-region study population than the state as a whole. African-American males did not experience any statistically significant reductions in CVD risk factor prevalence rates between 1990 and 1996, while the increase in obesity was driven mostly by the African-American female subgroup. The least amount of reduction in CVD risk factors was seen in individuals aged 55 or older, with a high school education or less and/or without health insurance. CONCLUSIONS: Individuals of African-American ethnicity, aged 55 or older, with a high school education or less and/or without health insurance need to be the focus of future public health initiatives designed to reduce the prevalence of CVD risk factors.

Profile of TQM in a dental practice.

A private practitioner describes the application of TQM concepts to his practice. Customer focus is illustrated through a survey, teamwork through enhanced communication, process improvement through a flow diagram, and overall quality through graphs showing the effects of handoffs among office staff.

Relation of biophysical response of coarcted aortic segment to balloon dilatation with development of recoarctation following balloon angioplasty of native coarctation.

OBJECTIVE: To evaluate the role of biophysical response of the coarcted segment to balloon dilatation in the causation of aortic recoarctation. SETTING: Tertiary care centre/university hospital. DESIGN: Retrospective case series. METHODS: Records of 67 consecutive infants and children undergoing balloon angioplasty of native aortic coarctations were examined for an 8.7 year period ending September 1993. At 12 months (median) follow up catheterisation, 15 (25%) of 59 children developed recoarctation, defined as a gradient > 20 mm Hg. Stretch (balloon circumference--preballoon coarcted segment circumference/preballoon coarcted segment circumference), gain (postballoon coarcted segment circumference--preballoon coarcted segment circumference), and recoil (balloon circumference--postballoon coarcted segment circumference) were calculated from measurements obtained from cineangiograms performed before and immediately after balloon dilatation. RESULTS: The stretch in 44 children without recoarctation (2.18 (1.23)) was similar (p > 0.1) to that in 15 children with recoarctation (1.90 (0.65)), implying that similar balloon dilating stretch was applied in both groups. Greater gain (p < 0.05) was observed in the group without recoarctation (8.8 (8.0) mm) than in the recoarctation group (5.7 (2.7) mm) but this was not substantiated in the infant population. However, the recoil was greater (p < 0.001) in the group without recoarctation (5.1 (4.3) mm) than in the recoarctation group (2.1 (1.1) mm); this was also true in the infant group. CONCLUSIONS: Greater recoil in the patients without recoarctation implies preservation of intact elastic tissue in the coarcted segment. In the recoarctation group, with less recoil, the elastic properties may not have been preserved, thereby causing recoarctation. There might be a more severe degree of cystic medial necrosis in the recoarctation group than in the no recoarctation group. This needs confirmation in future studies.

Transthoracic Doppler echocardiography of normally originating coronary arteries in children.

Transthoracic Doppler color flow and spectral velocity patterns of normal coronary arteries in children have not been well studied. We designed this study to evaluate coronary artery flow velocity characteristics in normal and hypertrophied hearts. Sixty-eight children with optimal two-dimensional echocardiographic images of the left coronary artery (LCA) and right coronary artery (RCA) were prospectively studied. The heart was normal in 45 children, and 23 had left and/or right ventricular hypertrophy assessed by echocardiography (mean age 5.8 versus 5.2 years, p = NS). Color flow signals were detected in the LCA in 63(92%) of the 68 children studied, and pulsed Doppler spectral waveforms were recorded in 47 (69%). The latter were recorded in 26 (58%) of 45 normal children and in 21 (91%) of 23 children with left ventricular hypertrophy. Diastolic RCA flow signals were detected mostly in those with right ventricular hypertrophy (10 of 10). Higher levels of LCA maximum diastolic velocity (42 +/- 23 versus 24 +/- 6 cm/sec, p = 0.0004), increased diastolic flow (16 +/- 15 versus 6 +/- 4 ml/min, p = 0.01), and delayed time to peak diastolic velocity expressed as a percentage of diastolic spectral duration (38% +/- 14% versus 20% +/- 8%, p = 0.0001) were observed in children with left ventricular hypertrophy than in those in normal children. A strong correlation was present between Doppler-derived LCA flow and left ventricular mass/m2 (r = 0.7, p = 0.001). In normal hearts, LCA spectral velocity pattern did not change with increasing age, but the time velocity integral became progressively larger, resulting in a strong correlation with weight (p < 0.001, r = 0.78). This study demonstrates (1) LCA flow signals can be detected and quantitated in the majority of children with and those without left ventricular hypertrophy. (2) Left ventricular hypertrophy is associated with increased LCA flow, higher diastolic velocity, and delayed peak diastolic velocity. (3) RCA flow signals are mostly detected when there is right ventricular hypertrophy. Studies on larger groups of patients are needed to further confirm our observations and to enhance understanding of coronary artery flow reserve.

Neurodevelopmental precursors to learning disabilities: a preliminary report from a parent survey.

This study documented the number and type of neurodevelopmental problems reported by parents of children with and without learning disabilities (LD), and examined whether a pattern of problems could be identified. One hundred parents, 50 for each group, responded to a retrospective developmental survey. Their children were between 9 and 13 years of age and had a history of either typical academic achievement or classification of a learning disability. Results indicated that the children with learning disabilities were reported to have significantly more neurodevelopmental problems or delays across domains (e.g., language, motor, attention, social behavior) than normal achievers. The study showed that a sizeable portion, although not all, of the children with LD had a history of neurodevelopmental problems. Despite findings that suggest that some difficulties more commonly co-occurred than others, a pattern of neurodevelopmental difficulties was not observed in these children. However, some specific difficulties, such as with following multistep directions, printing letters of the alphabet, and understanding directions (e.g., up, down, right, left), seemed to most typify the students with learning disabilities.

Genetic and environmental contributions to smoking.

We estimate the magnitude of genetic and shared environmental contributions to risk of initiation and maintenance of smoking. Genetic models were fitted to data from 2,204 male-male monozygotic and 1,793 male-male dizygotic twin pairs from the Vietnam Era Twin Registry who responded to smoking questions on a 1987 mail and telephone survey. The best fitting model allowed for both genetic and shared environmental effects on smoking initiation, accounting for 50% and 30% of the variance in risk, but allowed for only genetic effects, (accounting for 70% of the variance in risk), on persistence in smoking among those who had become regular smokers. This finding of a major genetic influence on smoking persistence confirms similar results from studies in Scandinavia and Australia. The role of heritable traits such as nicotine sensitivity should be addressed in smoking prevention and cessation efforts.

Leukocytosis: a new look at an old marker for acute myocardial infarction.

OBJECTIVE: To determine the test performance of leukocytosis for identifying acute myocardial infarction (AMI) in patients with nondiagnostic ECGs, admitted to rule out AMI. METHODS: A retrospective, comparative test performance study was conducted using patients admitted to a university teaching hospital to rule out AMI. Clinical and laboratory information was reviewed and hospital laboratory ranges were used to define threshold elevations: total creatine kinase (CK), 275 U/L; CK-MB, 7.5 micrograms/L ; white blood cell (WBC) count, 11.5 x 10(9)/L; and absolute neutrophil count (ANC), 8.0 x 10(9). Sensitivity, specificity, and predictive values of the total CK, CK-MB, WBC count, and ANC were calculated, and receiver operating characteristic (ROC) curves constructed. Test performances of marker combinations also were determined. RESULTS: The initial WBC count was significantly higher for the subjects who had AMI (11.1 vs 8.8 x 10(9)/L, p < 0.001). For the 688 subjects who had nondiagnostic ECGs, sensitivities for the initial total CK, CK-MB, WBC, and ANC were 39%, 73%, 35%, and 36%, respectively, while the corresponding specificities were 94%, 93%, 85%, and 86%. Logistic regression analysis confirmed leukocytosis as an independent predictor of AMI (adjusted odds ratio 4.08, 95% CI 1.73-9.63). While CK-MB alone was 73% sensitive for AMI, the decision rule of either an elevated CK-MB or an elevated WBC count increased this sensitivity to 88% (corresponding specificity 79%). Similarly, while CK-MB alone was 93% specific for AMI, the combination of an elevated CK-MB and an elevated WBC count increased this specificity to 99% (corresponding sensitivity 20%). CONCLUSIONS: Leukocytosis is significantly associated with AMI, and is a weak but independent laboratory predictor of this condition. In this preliminary study of admitted patients suspected of AMI, the combination of the WBC and the CK-MB may have additional diagnostic value over an isolated CK-MB result. Neither parameter in isolation was satisfactorily sensitive for AMI. Prognostic assessment of the role of the WBC count in clinical decision making should address its complementary role to that of other clinical and ancillary test parameters.