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Nicholas J Horton

Publications and source records attributed to Nicholas J Horton.

At least 37 records · Page 2Linked to original sources
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↗
PubMed2005

A multilevel study of socioeconomic predictors of regular mammography use among African-American women.

BACKGROUND: Little is known about the predictors of adherence to mammography guidelines by African-American women. We assessed individual-level and group-level socioeconomic predictors of regular mammography use in a large cohort of African-American women. METHODS: We included 14,706 participants in the Black Women's Health Study who were 40 to 69 years of age at baseline in 1995. Data were obtained through mail questionnaires at entry and biennially during three 2-year follow-up periods until 2001. We linked the women's addresses to census block (neighborhood) socioeconomic data. With multilevel multivariable regression analysis, we assessed the relation of individual-level and neighborhood socioeconomic factors to "regular" mammography use (use in all three follow-up periods) relative to nonregular use, with control for other predictors. RESULTS: Most participants had health insurance and almost half had graduated college. Having health insurance was the socioeconomic variable most strongly associated with regular mammography use (odds ratio, 3.59; 95% confidence interval 3.02-4.28); the association was present at all levels of educational attainment, household income, and neighborhood socioeconomic status. Regular mammography use increased with individual household income: odds ratio, 2.00 (95% confidence interval, 1.58-2.53) for household income > USD $100,000 relative to < USD $15,001. Regular mammography use did not vary across level of education. Higher neighborhood socioeconomic status was significantly associated with regular mammography use before, but not after, control for household income. CONCLUSIONS: Access to health insurance is strongly associated with regular mammography use among African-American women, even at higher levels of educational attainment and socioeconomic status. Neighborhood socioeconomic characteristics do not materially influence regular use.

Adult↗
PubMed2005

A randomized controlled trial to enhance antiretroviral therapy adherence in patients with a history of alcohol problems.

OBJECTIVE: To assess the effectiveness of an individualized multicomponent intervention to promote adherence to antiretroviral therapy (ART) in a cohort of HIV-infected individuals with a history of alcohol problems. DESIGN: We conducted a randomized controlled trial to compare the usual medical follow-up with an adherence intervention. SETTING: The principal enrolment site was Boston Medical Center, a private, not-for-profit, academic medical institution. SUBJECTS: HIV-infected patients with a history of alcohol problems on ART. A total of 151 were enrolled and 141 (93%) were assessed at follow-up. INTERVENTION: A nurse, trained in motivational interviewing, completed the following over 3 months in four encounters: addressed alcohol problems; provided a watch with a programmable timer to facilitate pill taking; enhanced perception of treatment efficacy; and delivered individually tailored assistance to facilitate medication use. MAIN OUTCOME MEASURES: Prior 30-day adherence > or =95%, prior 3-day adherence of 100%, CD4 cell count, HIV RNA and alcohol consumption, each at both short- and long-term follow-up. RESULTS: At follow-up, no significant differences in medication adherence, CD4 cell count, HIV RNA or alcohol consumption were found (all P values >0.25). CONCLUSIONS: A multicomponent intervention to enhance adherence among HIV-infected individuals with a history of alcohol problems was not associated with changes in medication adherence, alcohol consumption or markers of HIV disease progression. The failure to change adherence in a group at high risk for poor adherence, despite utilizing an intensive individual-focused patient intervention, supports the idea of addressing medication adherence with supervised medication delivery or markedly simplified dosing regimens.

Adult↗
PubMed2005

Addressing smoking cessation in methadone programs.

Little is known about how well methadone programs address smoking cessation. We describe the frequency of smoking cessation counseling, and factors affecting its provision in methadone programs. We conducted a cross-sectional survey of methadone patients and their counselors. Of 575 patients, 76% were eligible smokers. Although only 48% of patients reported receiving smoking cessation counseling within the previous six months, 97% of counselors reported providing it (p < 0.0001). Time with one counselor was significantly associated with patient report of receiving smoking cessation counseling (OR 1.19 [95% CI 1.04-1.36]). Although addiction counseling is required in methadone programs, nicotine addiction is addressed less than half the time. Methadone programs should prioritize the provision of effective smoking cessation and facilitate continuity of patient-counselor relationships.

Adult↗
PubMed2004

Suicidal behavior, drug use and depressive symptoms after detoxification: a 2-year prospective study.

INTRODUCTION: Individuals with substance-related disorders are at increased risk for suicidal behavior. Identifying those at higher risk for suicide among this population is difficult and informed mainly on the basis of cross-sectional data. METHODS: We examined factors associated with drug-related suicidal behavior using multivariable regression analyses in a 2-year prospective study of 470 inpatients enrolled from an unlocked, detoxification unit. Suicidal behavior included suicidal ideation (SI) and suicide attempt (SA). RESULTS: Lifetime prevalence for SI was 28.5%, and for SA, 21.9%. During the 2-year follow-up, 19.9% of the sample endorsed suicidal ideation and 6.9% reported a suicide attempt. Correlates of lifetime suicidal behavior included younger age, female, Hispanic, greater depressive symptoms, past sexual abuse, and problem sedative or alcohol use. Factors associated with suicidal behavior at follow-up included past suicidal behavior, more depressive symptoms, and more frequent benzodiazepine and alcohol use. Cocaine and heroin use did not reach statistical significance. CONCLUSIONS: Suicidal behavior is common among individuals with substance-related disorders. Differences in "suicide potential" may exist between drug categories with CNS depressants increasing the risk. These findings highlight the importance of addressing the recurrent 'suicide risk' of patients with substance-related disorders and regular monitoring for changes in depressive symptoms and drug use. Based on the prevalence and severity of this problem, the role of universal suicide screening of individuals with substance-related disorders merits greater attention.

Adult↗
PubMed2004

Regression analysis of multiple source and multiple informant data from complex survey samples.

In this tutorial, we describe regression-based methods for analysing multiple source data arising from complex sample survey designs. We use the term 'multiple-source' data to encompass all cases where data are simultaneously obtained from multiple informants, or raters (e.g. self-reports, family members, health care providers, administrators) or via different/parallel instruments, indicators or methods (e.g. symptom rating scales, standardized diagnostic interviews, or clinical diagnoses). We review regression models for analysing multiple source risk factors or multiple source outcomes and show that they can be considered special cases of generalized linear models, albeit with correlated outcomes. We show how these methods can be extended to handle the common survey features of stratification, clustering, and sampling weights. We describe how to fit regression models with multiple source reports derived from complex sample surveys using general purpose statistical software. Finally, the methods are illustrated using data from two studies: the Stirling County Study and the Eastern Connecticut Child Survey.

Data Collection↗
PubMed2004

Inconsistent condom use among HIV-infected patients with alcohol problems.

BACKGROUND: Unsafe sexual behavior is common among persons with negative or unknown HIV status and it is augmented by alcohol use in some populations. We examined the association between alcohol consumption level (abstinent, moderate, at-risk) and inconsistent condom use in a cohort of HIV-infected individuals with a history of alcohol problems. METHODS: Subjects (n=345) had up to seven structured interviews over 36 months. Identical questions on alcohol consumption and inconsistent condom use were asked at each interview. We used generalized estimating equations (GEE) multivariate logistic regression for repeated measurements analysis. We adjusted for potential confounding factors and explored possible interactions. RESULTS: At baseline, 132 (38%) participants reported inconsistent condom use. We detected a significant (P=0.0002) interaction between alcohol consumption and injection drug use (IDU) variables. Among active injection drug users, at-risk drinking was associated with inconsistent condom use, adjusted odds ratio (OR; 95% confidence interval) 4.3 (1.5, 12.2). Among those who did not inject drugs, at-risk drinking and inconsistent condom use were not associated, 0.7 (0.4, 1.3). Inconsistent condom use was more common among women, those believing condoms to be 'a hassle', and persons living with a partner. CONCLUSION: In HIV-infected drug-injecting individuals, excessive use of alcohol is associated with unsafe sexual practices.

Adult↗
PubMed2004

Detecting alcohol problems in HIV-infected patients: use of the CAGE questionnaire.

The HIV epidemic has been consistently associated with injection drug use and crack cocaine, but alcohol problems in HIV-infected persons are less well described. Our objectives were 2-fold: (1) to assess the prevalence of alcohol problems in HIV-infected patients initiating medical care; and (2) to determine the positive predictive value of the CAGE questionnaire for alcohol abuse or dependence in HIV-infected patients. Between July 1997 and October 2000, we assessed a consecutive series of patients who were establishing primary care for HIV infection (clinic sample), using an established alcohol screening test, the CAGE questionnaire. In addition, we enrolled other HIV-infected patients, including some of the clinic sample, who had two or more positive responses to the CAGE questionnaire into a longitudinal cohort (cohort sample), performed a diagnostic interview for lifetime history of alcohol abuse and dependence, and determined the positive predictive value of CAGE for alcohol diagnoses. In the clinic sample (n = 664), 42% (276 of 664) had two or more positive responses to the four CAGE questions. In the cohort sample (n = 141), 95% (134 of 141) met DSM-IV criteria for diagnosis of lifetime alcohol abuse or dependence. For patients initiating HIV primary care, a history of alcohol problems is very common. The CAGE questionnaire identifies a lifetime history of alcohol abuse or dependence in HIV-infected patients. Routine screening for alcohol problems should be performed in all patients entering HIV medical care and the CAGE questions are useful in this setting.

Adult↗
PubMed2004

Alcohol consumption and antiretroviral adherence among HIV-infected persons with alcohol problems.

BACKGROUND: Alcohol abuse has been associated with poor adherence to highly active antiretroviral therapy (HAART). We examined the relative importance of varying levels of alcohol consumption on adherence in HIV-infected patients with a history of alcohol problems. METHODS: We surveyed 349 HIV-infected persons with a history of alcohol problems at 6-month intervals. Of these subjects, 267 were taking HAART at one or more time periods during the 30-month follow-up period. Interviews assessed recent adherence to HAART and past month alcohol consumption, defined as "none", "moderate", and "at risk". We investigated the relationship between adherence to HAART and alcohol consumption at baseline and at each subsequent 6-month follow-up interval using multivariable longitudinal regression models, while controlling for potential confounders. RESULTS: Among the 267 HIV-infected persons with a history of alcohol problems who were receiving HAART, alcohol consumption was the most significant predictor of adherence (p < 0.0001), with better adherence being associated with recent abstinence from alcohol, compared with at-risk level usage (odds ratio = 3.6, 95% confidence interval = 2.1-6.2) or compared with moderate usage (odds ratio = 3.0, 95% confidence interval = 2.0-4.5). CONCLUSIONS: Any alcohol use among HIV-infected persons with a history of alcohol problems is associated with worse HAART adherence. Addressing alcohol use in HIV-infected persons may improve antiretroviral adherence and ultimately clinical outcomes.

Adult↗
PubMed2004

Uptake and adherence to highly active antiretroviral therapy among HIV-infected people with alcohol and other substance use problems: the impact of substance abuse treatment.

AIM: We examined the association of substance abuse treatment with uptake, adherence and virological response to highly active antiretroviral therapy (HAART) among HIV-infected people with a history of alcohol problems. DESIGN: Prospective cohort study. METHODS: A standardized questionnaire was administered to 349 HIV-infected participants with a history of alcohol problems regarding demographics, substance use, use of substance abuse treatment and uptake of and adherence to HAART. These subjects were followed every 6 months for up to seven occasions. 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. Our outcome variables were uptake of antiretroviral therapy, 30-day self-reported adherence and HIV viral load suppression. FINDINGS: At baseline, 59% (205/349) of subjects were receiving HAART. Engagement in substance abuse treatment was independently associated with receiving antiretroviral therapy (adjusted OR; 95% CI: 1.70; 1.03-2.83). Substance abuse treatment was not associated with 30-day adherence or HIV viral load suppression. More depressive symptoms (0.48; 0.32-0.78) and use of drugs or alcohol in the previous 30 days (0.17; 0.11-0.28) were associated with worse 30-day adherence. HIV viral load suppression was positively associated with higher doses of antiretroviral medication (1.29; 1.15-1.45) and older age (1.04; 1.00-1.07) and negatively associated with use of drugs or alcohol in the previous 30 days (0.51; 0.33-0.78). CONCLUSION: Substance abuse treatment was associated with receipt of HAART; however, it was not associated with adherence or HIV viral load suppression. Substance abuse treatment programs may provide an opportunity for HIV-infected people with alcohol or drug problems to openly address issues of HIV care including enhancing adherence to HAART.

Adult↗
PubMed2004

Linkage with primary medical care in a prospective cohort of adults with addictions in inpatient detoxification: room for improvement.

OBJECTIVE: To identify patient characteristics and health care experiences associated with primary care linkage after alcohol or drug detoxification. DATA SOURCES/STUDY SETTING: Primary data collected over two years. Subjects were adults without primary medical care, in an urban residential detoxification program. STUDY DESIGN: A prospective cohort study in the context of a randomized trial of a linkage intervention, and an expansion of Medicaid benefits. DATA COLLECTION/EXTRACTION METHODS: Data were collected by interview assessment of predisposing, enabling, and illness variables. Linkage was defined as self-report of at least one visit with a primary care clinician during follow-up. PRINCIPAL FINDINGS: Of 400 subjects, 63 percent linked with primary medical care. In a multivariable model adjusting for randomization assignment, predisposing, enabling, and illness variables, women, those with no recent incarceration, those with support for abstinence by family or friends, and those who had visited a medical clinic or physician recently were significantly more likely to link with primary care. Those with health insurance during follow-up were also more likely to link. Recent mental health or addictions treatment utilization and health status were not associated with linkage. CONCLUSIONS: A substantial proportion of adults with addictions do not link with primary medical care. These data suggest that efforts could be focused on those least likely to link, that contacts with mental health and addictions treatment providers are underutilized opportunities for these efforts, and that health policy changes such as expanding health insurance benefits may improve entry of substance-dependent patients into primary medical care.

Adult↗
PubMed2004

Assessing missed opportunities for HIV testing in medical settings.

BACKGROUND: Many HIV-infected persons learn about their diagnosis years after initial infection. The extent to which missed opportunities for HIV testing occur in medical evaluations prior to one's HIV diagnosis is not known. DESIGN: We performed a 10-year retrospective chart review of patients seen at an HIV intake clinic between January 1994 and June 2001 who 1). tested positive for HIV during the 12 months prior to their presentation at the intake clinic and 2). had at least one encounter recorded in the medical record prior to their HIV-positive status. Data collection included demographics, clinical presentation, and whether HIV testing was recommended to the patient or addressed in any way in the clinical note. Prespecified triggers for physicians to recommend HIV testing, such as specific patient characteristics, symptoms, and physical findings, were recorded for each visit. Multivariable logistic regression was used to identify factors associated with missed opportunities for discussion of HIV testing. Generalized estimating equations were used to account for multiple visits per subject. RESULTS: Among the 221 patients meeting eligibility criteria, all had triggers for HIV testing found in an encounter note. Triggers were found in 50% (1702/3424) of these 221 patients' medical visits. The median number of visits per patient prior to HIV diagnosis to this single institution was 5; 40% of these visits were to either the emergency department or urgent care clinic. HIV was addressed in 27% of visits in which triggers were identified. The multivariable regression model indicated that patients were more likely to have testing addressed in urgent care clinic (39%), sexually transmitted disease clinic (78%), primary care clinics (32%), and during hospitalization (47%), compared to the emergency department (11%), obstetrics/gynecology (9%), and other specialty clinics (10%) (P <.0001). More recent clinical visits (1997-2001) were more likely to have HIV addressed than earlier visits (P <.0001). Women were offered testing less often than men (P =.07). CONCLUSIONS: Missed opportunities for addressing HIV testing remain unacceptably high when patients seek medical care in the period before their HIV diagnosis. Despite improvement in recent years, variation by site of care remained important. In particular, the emergency department merits consideration for increased resource commitment to facilitate HIV testing. In order to detect HIV infection prior to advanced immunosuppression, clinicians must become more aware of clinical triggers that suggest a patient's increased risk for this infection and lower the threshold at which HIV testing is recommended.

AIDS Serodiagnosis↗
PubMed2003

Screening for sexually transmitted infections in substance abuse treatment programs.

OBJECTIVES: We evaluated the prevalence of the sexually transmitted infections (STIs) chlamydia and gonorrhea in clients at a methadone maintenance program and a residential detoxification program. METHODS: We collected urine specimens for chlamydia and gonorrhea ligase chain reaction testing and assessed sexual, substance abuse and STI histories. RESULTS: Of 700 subject assessments, 490 occurred among detoxification clients and 210 in methadone maintenance. Chlamydia trachomatis was detected in 5/700 (0.9, 95% CI=0.1-1.8%) and Neisseria gonorrhoeae in none. All chlamydia infected subjects were recruited from the detoxification program. Subjects reported high risk sexual behavior: 17% reported commercial sex exchange, and 22% reported inconsistent condom use with multiple sexual partners during the prior 2 months. CONCLUSION: Based on prevalence in Boston, MA, universal screening for STI in substance abuse treatments programs is not warranted. However, routine screening for younger substance abusers and in communities with high prevalence should be considered.

Adult↗
PubMed2003

Dual effect of parity on breast cancer risk in African-American women.

BACKGROUND: In the United States, breast cancer incidence is higher among African-American women than among white women before age 45 but lower at older ages. To explore whether differences in childbearing patterns can explain this observation, we assessed the relation of several childbearing variables to breast cancer risk in a large prospective cohort study of U.S. African-American women. METHODS: Black Women's Health Study participants were enrolled in 1995 and were followed by mailed questionnaires every 2 years (in 1997 and 1999). Of the 64,500 women enrolled, 56,725 (88%) completed at least one of the follow-up questionnaires. During 214,862 person-years of follow-up, participants reported 349 breast cancers, of which 128 were among women younger than 45 years and 221 were among women aged 45-70 years. Incidence rate ratios (IRRs) with 95% confidence intervals (CIs) were derived from age-stratified Cox regression models that adjusted for each of the childbearing variables (parity, age at first birth, and time since last birth). RESULTS: Compared with primiparity, high parity was associated with an increased risk of breast cancer among women younger than 45 years (IRR for four or more births = 2.4, 95% CI = 1.1 to 5.1) and a decreased risk among women aged 45 years and older (IRR = 0.5, 95% CI = 0.3 to 0.9). The IRR for late age at first birth compared with early age was 2.5 (95% CI = 1.1 to 5.8) among the younger women and was not elevated among older women. We found no statistically significant association of time since last birth with breast cancer risk among either younger or older women. CONCLUSIONS: Parity has a dual association with breast cancer risk in African-American women; among women younger than 45 years, parity is associated with an increased risk and among women 45 years and older it is associated with a decreased risk. This dual effect may explain some of the observed differences in breast cancer incidence rates among African-American and white women.

Adult↗
PubMed2003

Addressing alcohol problems in primary care: a cluster randomized, controlled trial of a systems intervention. The screening and intervention in primary care (SIP) study.

BACKGROUND: Screening and intervention for alcohol problems can reduce drinking and its consequences but are often not implemented. OBJECTIVE: To test whether providing physicians with patients' alcohol screening results and simple individualized recommendations would affect the likelihood of a physician's having a discussion with patients about alcohol during a primary care visit and would affect subsequent alcohol use. DESIGN: Cluster randomized, controlled trial. SETTING: Urban academic primary care practice. PARTICIPANTS: 41 faculty and resident primary care physicians and 312 patients with hazardous drinking. INTERVENTIONS: Providing physicians with alcohol screening results (CAGE questionnaire responses, alcohol consumption, and readiness to change) and recommendations for their patients at a visit. MEASUREMENTS: Patient self-report of discussions about alcohol use immediately after the physician visit and alcohol use 6 months later. RESULTS: Of 312 patients, 240 visited faculty physicians, 301 (97%) completed the outcome assessment after the office visit, and 236 (76%) were followed for 6 months. Faculty physicians in the intervention group tended to be more likely than faculty physicians in the control group to give patients advice about drinking (adjusted proportion, 64% [95% CI, 47% to 79%] vs. 42% [CI, 33% to 53%]) and to discuss problems associated with alcohol use (74% [CI, 59% to 85%] vs. 51% [CI, 39% to 62%]). Resident physicians' advice and discussions did not differ between groups. Six months later, patients who saw resident physicians in the intervention group had fewer drinks per drinking day (adjusted mean number of drinks, 3.8 [CI, 1.9 to 5.7] versus 11.6 [CI, 5.4 to 17.7]). CONCLUSIONS: Although effects seem to differ by physician level of training, prompting physicians with alcohol screening results and recommendations for action can modestly increase discussions about alcohol use and advice to patients and may decrease alcohol consumption.

Adult↗
PubMed2003

Bias due to missing exposure data using complete-case analysis in the proportional hazards regression model.

We studied bias due to missing exposure data in the proportional hazards regression model when using complete-case analysis (CCA). Eleven missing data scenarios were considered: one with missing completely at random (MCAR), four missing at random (MAR), and six non-ignorable missingness scenarios, with a variety of hazard ratios, censoring fractions, missingness fractions and sample sizes. When missingness was MCAR or dependent only on the exposure, there was negligible bias (2-3 per cent) that was similar to the difference between the estimate in the full data set with no missing data and the true parameter. In contrast, substantial bias occurred when missingness was dependent on outcome or both outcome and exposure. For models with hazard ratio of 3.5, a sample size of 400, 20 per cent censoring and 40 per cent missing data, the relative bias for the hazard ratio ranged between 7 per cent and 64 per cent. We observed important differences in the direction and magnitude of biases under the various missing data mechanisms. For example, in scenarios where missingness was associated with longer or shorter follow-up, the biases were notably different, although both mechanisms are MAR. The hazard ratio was underestimated (with larger bias) when missingness was associated with longer follow-up and overestimated (with smaller bias) when associated with shorter follow-up. If it is known that missingness is associated with a less frequently observed outcome or with both the outcome and exposure, CCA may result in an invalid inference and other methods for handling missing data should be considered.

Alleles↗