PubMed Health⌕ Search

Biomedical subjects

Nicholas J Horton

Publications and source records attributed to Nicholas J Horton.

At least 19 recordsLinked to original sources
PubMed2007

Incorporating missingness for estimation of marginal regression models with multiple source predictors.

Multiple informant data refers to information obtained from different individuals or sources used to measure the same construct; for example, researchers might collect information regarding child psychopathology from the child's teacher and the child's parent. Frequently, studies with multiple informants have incomplete observations; in some cases the missingness of informants is substantial. We introduce a Maximum Likelihood (ML) technique to fit models with multiple informants as predictors that permits missingness in the predictors as well as the response. We provide closed form solutions when possible and analytically compare the ML technique to the existing Generalized Estimating Equations (GEE) approach. We demonstrate that the ML approach can be used to compare the effect of the informants on response without standardizing the data. Simulations incorporating missingness show that ML is more efficient than the existing GEE method. In the presence of MCAR missing data, we find through a simulation study that the ML approach is robust to a relatively extreme departure from the normality assumption. We implement both methods in a study investigating the association between physical activity and obesity with activity measured using multiple informants (children and their mothers).

Bias↗
PubMed2006

Acculturation status and heavy alcohol use among Mexican American college students: investigating the moderating role of gender.

We examined whether gender moderates the association between acculturation and heavy alcohol use. The sample consisted of 126 Mexican American college students (Mean age=24.7 years; 57% female) who completed self-report measures of heavy alcohol use, acculturation status (global acculturation and ethnic identity), and relevant control variables (age, peer alcohol use). Multivariable regression revealed that higher levels of ethnic identity were associated with greater frequency of heavy alcohol among men. Conversely, neither measure of acculturation was associated with heavy alcohol use among women. These findings suggest that interventions for Latino/a students should consider the role of culturally relevant variables in heavy alcohol use, particularly for men. They also have implications regarding how acculturation is operationalized in alcohol studies, and suggest directions for future research.

Acculturation↗
PubMed2006

Episodic homelessness and health care utilization in a prospective cohort of HIV-infected persons with alcohol problems.

BACKGROUND: Because individuals with HIV/AIDS often have complex medical and social needs, the impact of housing status on medical service utilization is difficult to isolate from the impact of conditions that may worsen during periods of homelessness such as depression and substance abuse. We examine whether episodes of homelessness are independently associated with suboptimal medical utilization even when accounting for concurrent addiction severity and depression. METHODS: We used data from a 30-month cohort of patients with HIV/AIDS and alcohol problems. Housing status, utilization (ambulatory visits, emergency department (ED) visits, and hospitalizations) and other features were assessed with standardized research interviews at 6-month intervals. Multivariable longitudinal regression models calculated incidence rate ratios (IRR) comparing utilization rates during 6-month intervals (homeless versus housed). Additional models assessed whether addiction severity and depressive symptoms could account for utilization differences. RESULTS: Of the 349 subjects, 139 (39%) reported homelessness at least once during the study period; among these subjects, the median number of nights homeless per 6-month interview period was 30. Homelessness was associated with higher ED utilization (IRR = 2.17; 95% CI = 1.72-2.74) and hospitalizations (IRR = 2.30; 1.70-3.12), despite no difference in ambulatory care utilization (IRR = 1.09; 0.89-1.33). These associations were attenuated but remained significant when adjusting for addiction severity and depressive symptoms. CONCLUSION: In patients with HIV/AIDS and alcohol problems, efforts to improve housing stability may help to mitigate intensive medical utilization patterns.

Adult↗
PubMed2006

Racial discrimination and the incidence of hypertension in US black women.

PURPOSE: Unique experiences associated with "race," such as racism, may adversely affect health. Our goal is to assess whether racism is associated with the occurrence of hypertension in African-American women. METHODS: In the first prospective examination of perceived experiences of racism in relation to the incidence of hypertension, we used data from the Black Women's Health Study, a follow-up study of US black women that began in 1995. The 1997 follow-up questionnaire contained eight questions designed to measure personally mediated racism and institutionalized racism. Cox proportional hazard models were used to estimate incidence rate ratios (IRRs), with control for age, body mass index, and questionnaire period. RESULTS: There were 2316 incident cases of hypertension reported during 104,574 person-years of observation from 1997 to 2001. Most women reported experiences of racism. In the total sample, IRRs for the association of racism with incident hypertension were close to the null. However, some positive associations were observed for personally mediated racism in women born outside the United States. CONCLUSIONS: There may be an increase in hypertension associated with experiences of racism in certain subgroups of African-American women.

Black People↗
PubMed2006

Association of violence victimization with inconsistent condom use in HIV-infected persons.

The association of violence victimization with current condom use in HIV-infected persons was examined in this cross-sectional study. The HIV-Alcohol Longitudinal Cohort (HIV-ALC) recruited HIV-infected participants with a history of alcohol problems. Interviews assessed violence histories and current sexual behaviors. Of the 349 participants (79% men), 38% reported inconsistent condom use and 80% reported a violence history. Lifetime sexual violence was reported by 40% and lifetime physical violence (without sexual violence) by 40%. Participants reporting lifetime sexual violence had greater odds of inconsistent condom use than participants without any history of violence. A history of childhood sexual violence was also associated with greater odds of inconsistent condom use than participants without a history of childhood sexual violence. A history of sexual violence may in part explain HIV-infected persons' greater risk for transmitting HIV through high-risk sexual behaviors.

Adult↗
PubMed2006

Do good things come to those who drink? A longitudinal investigation of drinking expectancies and hazardous alcohol use in female college athletes.

PURPOSE: To prospectively examine the link between positive and negative drinking expectancies and hazardous alcohol use, and to explore the reciprocal associations between expectancies and hazardous use among female college athletes. METHOD: Participants were part of a larger (n = 189), ongoing longitudinal study on female athletes' socialization experiences and health behaviors from an all-women's college in the Northeastern United States. The sample for the present study were 85 college-aged (17-22 years) female students (Mean age = 19.6) who indicated alcohol use in the past year and provided data at both time points (baseline and one year later). Respondents completed self-report questionnaires on their age, hazardous alcohol use, and expectations about the effects of drinking. RESULTS: Logistic regression analyses showed that positive drinking expectancies predicted increased odds of hazardous alcohol use at baseline and one year later (even after controlling for baseline hazardous use). Positive expectancies accounted for a higher proportion of variance in predicting increased odds of hazardous alcohol use at both time points than did negative expectancies. Bivariate correlational analyses examining the bi-directional associations between expectancies and hazardous alcohol use also revealed some indication that positive expectancies were associated with hazardous alcohol use rather than vice-versa. No such relations emerged for negative expectancies. CONCLUSIONS: Findings shed light on the utility of positive expectancies in predicting concurrent and subsequent hazardous alcohol use among female student-athletes. Future research directions and potential implications for prevention efforts are discussed.

Adolescent↗
PubMed2006

Emergency department and hospital utilization among alcohol and drug-dependent detoxification patients without primary medical care.

Utilization of emergency department (ED) services and hospitalization among a cohort of substance abusers are described based on structured research interviews with 470 adults without primary care admitted to an urban residential detoxification program. Cross-sectional analysis of baseline data of subjects found nearly 19% of subjects went to an ED on 2 or more occasions in the 6 months prior to detoxification and 14% were admitted for an overnight hospitalization. Upon further analysis of past 6-month ED utilization, the following factors were independently associated with increased odds of ED use: White race; at least one month homeless in the past 5 years chronic health condition; injury in past 6 months; and subject perception that their substance abuse interfered with seeking care from a regular doctor. Subjects with cocaine as a primary problem had lower odds of ED utilization than a reference group with alcohol as a primary problem.

Adult↗
PubMed2006

The severity of unhealthy alcohol use in hospitalized medical patients. The spectrum is narrow.

BACKGROUND: Professional organizations recommend screening and brief intervention for unhealthy alcohol use; however, brief intervention has established efficacy only for people without alcohol dependence. Whether many medical inpatients with unhealthy alcohol use have nondependent use, and thus might benefit from brief intervention, is unknown. OBJECTIVE: To determine the prevalence and spectrum of unhealthy alcohol use in medical inpatients. DESIGN: Interviews of medical inpatients (March 2001 to June 2003). SUBJECTS: Adult medical inpatients (5,813) in an urban teaching hospital. MEASUREMENTS: Proportion drinking risky amounts in the past month (defined by national standards); proportion drinking risky amounts with a current alcohol diagnosis (determined by diagnostic interview). RESULTS: Seventeen percent (986) were drinking risky amounts; 97% exceeded per occasion limits. Most scored > or =8 on the Alcohol Use Disorders Identification Test, strongly correlating with alcohol diagnoses. Most of a subsample of subjects who drank risky amounts and received further evaluation had dependence (77%). CONCLUSIONS: Drinking risky amounts was common in medical inpatients. Most drinkers of risky amounts had dependence, not the broad spectrum of unhealthy alcohol use anticipated. Screening on a medicine service largely identifies patients with dependence--a group for whom the efficacy of brief intervention (a recommended practice) is not well established.

Adolescent↗
PubMed2006

Posture-induced changes in distortion-product otoacoustic emissions and the potential for noninvasive monitoring of changes in intracranial pressure.

INTRODUCTION: Intracranial pressure (ICP) monitoring is currently an invasive procedure that requires access to the intracranial space through an opening in the skull. Noninvasive monitoring of ICP via the auditory system is theoretically possible because changes in ICP transfer to the inner ear through connections between the cerebral spinal fluid and the cochlear fluids. In particular, low-frequency distortion-product otoacoustic emissions (DPOAEs), measured noninvasively in the external ear canal, have magnitudes that depend on ICP. Postural changes in healthy humans cause systematic changes in ICP. Here, we quantify the effects of postural changes, and presumably ICP changes, on DPOAE magnitudes. METHODS: DPOAE magnitudes were measured on seven normal-hearing, healthy subjects at four postural positions on a tilting table (angles 90 degrees , 0 degrees , - 30 degrees , and - 45 degrees to the horizontal). At these positions, it is expected that ICP varied from about 0 (90 degrees ) to 22 mm Hg ( - 45 degrees ). DPOAE magnitudes were measured for a set of frequencies 750 < f2 < 4000, with f2/f1 = 1.2. RESULTS: For the low-frequency range of 750 <or=f2<or= 1500, the differences in DPOAE magnitude between upright and - 45 degrees were highly significant (all p < 0.01), and above 1500 Hz there were minimal differences between magnitudes at 90 degrees versus - 45 degrees. There were no significant differences in the DPOAE magnitudes with subjects at 90 degrees and 0 degrees postures. CONCLUSIONS: Changes in ICP can be detected using the auditory-based measurement of DPOAEs. In particular, changes are largest at low frequencies. Although this approach does not allow for absolute measurement of ICP, it appears that measurement of DPOAEs may be a useful means of noninvasively monitoring ICP.

Acoustic Impedance Tests↗
PubMed2005

The use of the mini-mental state examination in recruitment for substance abuse research studies.

BACKGROUND: Substance abuse is associated with cognitive impairment. Participation in clinical addiction research can be cognitively demanding. Screening tools can identify cognitively impaired subjects. We examined the use of the mini-mental state examination (MMSE) as an entry criterion in three randomized controlled substance abuse clinical trials. METHODS: In each of the three studies, we calculated the proportion of subjects excluded due to MMSE scores (<21) suggestive of cognitive impairment. We estimated the potential impact on enrollment based on the number of excluded subjects. Separately, for two of the studies, we assessed the impact of cognitive function on participation in follow-up using multivariable logistic regression. RESULTS: Of all persons screened for enrollment, 1.6% (171/10,791) were ineligible based solely on a MMSE score of <21. We estimate that 119 of these 171 ineligible persons would have consented and enrolled. These 119 persons would have represented 9.3% of all enrolled subjects across these studies. For subjects in a study in an inpatient detoxification unit, a higher MMSE score was associated with higher odds (adjusted odds ratio 1.15, 95% CI 1.03-1.30) of completing at least one follow-up assessment. A similar impact on subject follow-up was not observed in a study of medical inpatients with unhealthy alcohol use (adjusted odds ratio 1.01, 95% CI 0.86-1.20). CONCLUSION: Screening for cognitive impairment using the MMSE excludes a small, but substantial, number of persons from addiction research studies. Cognitive ability, as captured by the MMSE may impact follow-up. These data support cognitive screening of substance abuse research subjects.

Adult↗
PubMed2005

Alcohol use and HIV risk behaviors among HIV-infected hospitalized patients in St. Petersburg, Russia.

PURPOSE: Russia has high per capita alcohol consumption and an injection-drug-use-driven HIV epidemic. However, the role of alcohol in the spread of HIV infection in Russia is largely unexplored. Thus, we assessed recent alcohol use and associated HIV risk behaviors among HIV-infected persons in St. Petersburg, Russia. METHODS: We recruited HIV-infected hospitalized patients from the Botkin Infectious Disease Hospital between June 2001 and March 2002. Interviewers assessed alcohol and drug use with the addiction severity index (ASI) and sex- and drug-risk behaviors with the risk assessment battery (RAB). Lifetime abuse or dependence diagnoses for alcohol and drugs were established by a physician with addiction medicine training. RESULTS: Among 201 subjects, diagnoses of abuse or dependence (AB/DEP) were common: 9% (19/201) had only alcohol AB/DEP; 39% (78/201) had alcohol and drug AB/DEP; 47% (95/201) had only drug AB/DEP; and 4% (9/201) had no diagnosis of alcohol or drug AB/DEP. Sex- and drug-risk behaviors varied significantly by substance use diagnosis. Subjects with any alcohol AB/DEP had higher sex-risk RAB scores than those with drug only AB/DEP (6.1 versus 3.9, p<.0001). Among subjects with any diagnosis of drug AB/DEP, having in addition an alcohol diagnosis was associated with unclean needle use in the last six months (33% (26/78) versus 21% (20/95), p=0.08). CONCLUSIONS: Lifetime alcohol diagnoses of abuse or dependence were present in nearly one-half of hospitalized HIV-infected patients in St. Petersburg, Russia and were associated with significantly higher sex-risk behaviors and borderline significantly higher drug-risk behaviors. As HIV infection spreads rapidly in Russia and Eastern Europe, these data support the need for HIV risk-reduction interventions in alcohol abusing populations and raise the potential of benefit by addressing alcohol use in HIV-infected populations.

Adult↗
PubMed2005

Substance abuse treatment and risk behaviors among HIV-infected persons with alcohol problems.

We examined the association of substance abuse treatment with sexual and drug use risk behaviors among 349 HIV-infected persons with a history of alcohol problems using a standardized questionnaire regarding sexual and drug use risk behaviors, demographics, substance use, and use of substance abuse treatment. We defined substance abuse treatment services as any of the following in the past 6 months: 12 weeks in a half-way house or residential facility; 12 visits to a substance abuse counselor or mental health professional; day treatment for at least 30 days; or participation in any methadone maintenance program. Our three outcome variables of high-risk behavior were the Risk Assessment Battery sex-risk and drug-risk scores and high-risk sex behavior which included any of the following: inconsistent condom use; having more than one sexual partner; and exchanging sex for money or drugs. Although sexual risk was high (51%) in our HIV-infected cohort, engagement in substance abuse treatment was not independently associated with lower frequency of any of our measures of high- risk behaviors. Although the opportunity exists to address HIV risk behaviors in the setting of substance abuse treatment, effective institutionalization of this challenging behavior change effort has not yet been realized.

Adult↗
PubMed2005

Relationship of depressive symptoms and mental health functioning to repeat detoxification.

To better understand residential detoxification use, we assessed the roles of depressive symptoms (DS) and mental health functioning (MHF) on repeat detoxification. A prospective cohort of residential detoxification patients (N=400) without primary medical care was followed over 2 years at 6-month intervals. Subsequent detoxification admissions were examined using a statewide administrative database and DS (Center for Epidemiologic Studies Depression Scale) and MHF (SF-36 mental component summary subscale) measurements at follow-up. Incidence rate ratios of return to detoxification were estimated using multivariable longitudinal Poisson regression. In separate analyses, greater DS and worse MHF predicted higher detoxification use rates. Clinically significant worsening (10 points) of DS and MHF on objective scales predicted a 20% increased rate of detoxification readmission. Male sex, heroin as a problem substance, and race/ethnicity each predicted detoxification use. These data suggest that identifying individuals with DS or worse MHF after detoxification may provide opportunities for clinical intervention to reduce recurrent residential detoxification.

Adolescent↗
PubMed2005

Substance abuse treatment and hospitalization among a cohort of HIV-infected individuals with alcohol problems.

BACKGROUND: We examined the association of substance abuse treatment services on hospitalization among participants in the HIV-Alcohol Longitudinal Cohort (HIV-ALC) study of HIV-infected individuals with a history of alcohol problems. METHODS: A standardized questionnaire that inquired about demographics, substance use, use of substance abuse treatment services, and hospitalization was administered to 349 HIV-ALC participants. We defined substance abuse treatment services as any of the following in the past 6 months: 12 weeks in a half-way house or residential facility, 12 visits to a substance abuse counselor or mental health professional, or participation in any methadone maintenance program. RESULTS: Almost one third of this cohort were hospitalized in the past 6 months. Substance abuse treatment was not significantly associated with hospitalization [adjusted odds ratio (AOR) 1.0; 95% confidence interval (CI) 0.7-1.5), whereas homelessness (AOR 2.3; 95% CI 1.5-3.6), injection drug use (AOR 1.7; 95% CI 1.0-2.7), severity of alcohol dependence (AOR 1.02; 95% CI 1.00-1.05), CD4 cell count (AOR 0.999; 95% CI 0.998-1.00), and HIV RNA (AOR 1.1; 95% CI 1.0-1.2) were independently associated with increased odds of hospitalization over time. CONCLUSIONS: Engagement in substance abuse treatment was not associated with a decrease in hospital use by HIV-infected individuals with a history of alcohol problems. The period of substance abuse treatment may present an opportunity to address health care utilization patterns of HIV-infected individuals.

Adult↗
PubMed2005

Health utility ratings for a spectrum of alcohol-related health states.

BACKGROUND: Preference-based utility ratings for health conditions are important components of cost-utility analyses and population burden of disease estimates. However, utility ratings for alcohol problems have not been determined. OBJECTIVES: The objectives of this study were to directly measure utility ratings for a spectrum of alcohol-related health states and to compare different methods of utility measurement. DESIGN, SETTING, AND SUBJECTS: The authors conducted a cross-sectional interview of 200 adults from a clinic and community sample. METHODS: Subjects completed computerized visual analog scale (VAS), time tradeoff (TTO), and standard gamble (SG) utility measurement exercises for their current health, a blindness scenario, and for 6 alcohol-related health state scenarios presented in random order. The main outcome measures were the utility ratings, scaled from 0 to 1, and anchored by death (0) and perfect health (1). RESULTS: The 200 subjects were middle-aged (mean, 41 +/- 14 years), 61% women, and racially diverse (48% black, 43% white). Utility ratings decreased as the severity of the alcohol-related health state increased, but differed significantly among the VAS, TTO, and SG methods within each health state. Adjusted mean (95% confidence interval) utility ratings for alcohol dependence (VAS, 0.38 [0.34-0.41]; TTO, 0.54 [0.48-0.60]; SG, 0.68 [0.63-0.73]) and alcohol abuse (VAS, 0.53 [0.49-0.56]; TTO, 0.71 [0.65-77]; SG, 0.76 [0.71-0.81]) were significantly lower than utility ratings for nondrinking, moderate drinking, at-risk drinking, current health, and blindness. CONCLUSIONS: Utility ratings for alcohol-related health states decrease as the severity of alcohol use increases. The low utility ratings for alcohol abuse and alcohol dependence are similar to those reported for other severe chronic medical conditions.

Academic Medical Centers↗
PubMed2005

Homeless chronicity and health-related quality of life trajectories among adults with addictions.

BACKGROUND: New federal initiatives target funds toward chronically homeless as distinct from other homeless persons. Few data exist, however, to substantiate the implications of chronic homelessness for major health outcomes. OBJECTIVES: Using data from a 2-year cohort of addicted persons, we tested whether changes in mental and physical health-related quality of life (HRQOL) differed according to homeless chronicity. METHODS: Using self-reported homelessness, we classified subjects as chronically homeless (CH; n = 60), transitionally homeless (TRANS; n = 108), or as housed comparison subjects (HSD; n = 106). The Short Form-36 Health Survey, administered at baseline and 2 follow-ups over a period of 2 years, provided a Mental Component Summary (MCS) and a Physical Component Summary (PCS) for HRQOL. Mixed model linear regression was used to test the association between housing status, MCS, and PCS. Additional models assessed whether medical, psychiatric, addiction, and social support measures could account for HRQOL differences. RESULTS: All subjects had low MCS scores at study entry (mean, 31.2; SD, 12.6). However, there was a significant housing status-by-time interaction (P = 0.01). At final follow-up, CH and TRANS subjects had lower adjusted MCS scores than HSD subjects (33.4, 38.8, and 43.7 for the 3 groups, respectively; all P < or = 0.01). By contrast, housing status and PCS were not significantly associated (P = 0.19). Medical, psychiatric, addiction, and social support variables had significant associations with MCS, and their inclusion in the regression reduced the apparent effect of housing status on MCS. CONCLUSIONS: Chronic homelessness was associated with especially poor mental but not physical HRQOL over time. These findings reinforce a new typology of homelessness.

Adult↗
PubMed2005

Primary medical care and reductions in addiction severity: a prospective cohort study.

AIMS: To assess whether receipt of primary medical care can lead to improved outcomes for adults with addictions. DESIGN: We studied a prospective cohort of adults enrolled in a randomized trial to improve linkage with primary medical care. METHODS: Subjects at a residential detoxification unit with alcohol, heroin or cocaine as a substance of choice, and no primary medical care were enrolled. Receipt of primary medical care was assessed over 2 years. Outcomes included (1) alcohol severity, (2) drug severity and (3) any substance use. FINDINGS: For the 391 subjects, receipt of primary care (> or = 2 visits) was associated with a lower odds of drug use or alcohol intoxication (adjusted odds ratio (AOR) 0.45, 95% confidence interval (CI) 0.29-0.69, 2 d.f. chi(2)P = 0.002). For 248 subjects with alcohol as a substance of choice, alcohol severity was lower in those who received primary care [predicted mean Addiction Severity Index (ASI) alcohol scores for those reporting > or = 2, 1 and 0 visits, respectively, 0.30, 0.26 and 0.34, P = 0.04]. For 300 subjects with heroin or cocaine as a substance of choice, drug severity was lower in those who received primary care (predicted mean ASI drug scores for those reporting > or = 2, 1 and 0 visits, respectively, 0.13, 0.15 and 0.16, P = 0.01). CONCLUSIONS: Receipt of primary medical care is associated with improved addiction severity. These results support efforts to link patients with addictions to primary medical care services.

Adult↗