Cigarette Smoking Prevalence Among Adults With HIV Compared With the General Adult Population in the United States

Editors' Notes Context Smoking is associated with increased illness and death in adults with HIV. Contribution In an analysis that included both a cohort and a cross-sectional study, adults with HIV were found to smoke more and were less likely to quit smoking than the general U.S. population. Modifiable risk factors independently associated with higher smoking prevalence among persons with HIV included homelessness, incarceration, substance abuse, binge drinking, depression, and not achieving HIV viral suppression. Implication Efforts to increase smoking cessation should be a routine component of HIV care programs. Cigarette smoking is a leading cause of illness and death in the United States, accounting for 480000 adult deaths annually (1). Moreover, the financial burden of smoking in direct medical expenses and lost productivity in the United States is high; estimated costs are $289 to $332 billion annually (1). For adults with HIV, cigarette smoking increases both HIV-related and nonHIV-related illness and death. Smoking-associated cancer (such as cancer of the lung, head and neck, cervix, and anus) has occurred at higher rates among adults with HIV than those in the general population (24). Respiratory complications of HIV infection, including chronic obstructive pulmonary disease (5), cryptococcal and bacterial pneumonia (6, 7), and pulmonary tuberculosis (810), have been associated with smoking. Cigarette smoking is also related to cardiovascular disease (11), a leading source of illness and death among persons with and without HIV in the United States. A recent study in Denmark found that the life-years lost among persons with HIV who smoked exceeded the estimated total losses attributed to each condition alone, suggesting that HIV infection and smoking act synergistically to increase mortality rates (12). Despite the preventable effect of smoking on the health of persons with HIV, prevalence among a representative sample of adults with HIV in the United States has not been well-characterized. Observational studies from selected samples of persons with HIV have suggested that smoking prevalence ranges from 40% to 70% (2, 11, 1317). However, observations from these studies have limited generalizability due to small sample size (13, 17), limited demography (2), or limited geography (15). We report cigarette smoking prevalence estimates from a nationally representative, geographically diverse sample of U.S. adults with HIV who received medical care to address the limitations in previous studies. We also assessed factors associated with cigarette smoking among adults with HIV, compared the prevalence of cigarette smoking among adults with HIV with the prevalence of cigarette smoking in the U.S. general adult population, and compared lifetime smoking cessation, as measured by the quit ratio, between adults with HIV and the general adult population. Methods Data Sources and Study Design We used data from the Medical Monitoring Project (MMP) and the National Health Interview Survey (NHIS) to estimate the prevalence of cigarette smoking among adults with HIV and adults in the general U.S. population. The MMP is a supplemental HIV surveillance system with a multistage probability design from which estimates of behavioral and clinical characteristics of adults with HIV who received HIV medical care in the United States are derived (1820). For the 2009 data collection cycle, data were collected between June 2009 and May 2010 using face-to-face interviews and medical record abstractions. Of 603 facilities within the states or territories sampled to participate in the MMP, 461 participated (facility response rate, 76%). Of 9338 sampled persons, data were available for 4217 who had a completed interview linked with medical record abstraction (adjusted patient-level response rate, 51%). Data were weighted based on known probabilities of selection in each state or territory, by facility, and for patients in selected facilities. Data were also weighted to adjust for nonresponse using predictors of patient-level response (that is, facility size, race or ethnicity, time since HIV diagnosis, and age group). The Centers for Disease Control and Prevention's (CDC) National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention has determined the MMP to be a nonresearch public health surveillance activity used to guide disease control programs and policy (21); therefore, it was not reviewed by a federal institutional review board. Participating states or territories and facilities obtained local institutional review board approval to conduct the MMP if required locally. Informed consent was obtained from all interviewed participants. The NHIS is a cross-sectional household interview survey with a multistage probability design that uses year-round continuous sampling and interviewing of a representative sample of households and noninstitutional group quarters (such as college dormitories) (22). The 2009 NHIS adult core questionnaire collected national health information on illness and disability through in-person interviews with a random probability sample of 27731 noninstitutionalized civilian adults aged 18 years or older; the overall response rate was 65.4%. The NHIS data were weighted to account for the sample design; account for the differential probability of selection and nonresponse; and adjust for the population totals of noninstitutionalized U.S. civilians according to age, sex, and race or ethnicity (23). Measures Smoking Status The primary outcome variable was current smoking status, defined based on respondents' answers to the following questions: Have you smoked at least 100 cigarettes in your entire life? (MMP and NHIS); Do you now smoke cigarettes every day, some days, or not at all? (NHIS only); and How often do you smoke cigarettes now? (MMP only). The response categories for the latter question were daily, weekly, monthly, less than monthly, and never. Current cigarette smokers were defined as persons who reported that they had smoked 100 cigarettes or more during their lifetime and currently smoked every day or some days. Never-smokers were defined as persons who reported that they had not smoked at least 100 cigarettes in their entire life, and former smokers were defined as those who reported smoking at least 100 cigarettes during their lifetime but were not currently smoking. The quit ratio, a measure of successful smoking cessation at the population level, was defined as the ratio of former smokers to ever-smokers (that is, the sum of current smokers and former smokers) (24). Demographic, Social, and Behavioral Variables Sociodemographic variables collected for the MMP analyses included age group, sex, race or ethnicity, sexual transmission risk, education, time since HIV diagnosis (in years), and poverty level (25). The following social and behavioral variables were reported by respondents based on the 12 months before their interviews: annual income, incarceration, homelessness, health insurance, depression (26, 27), and drug use (both injection and noninjection) for nonmedical purposes. Binge drinking in the 30 days before the interview was defined as 5 or more alcoholic drinks per day for men and 4 or more drinks per day for women (28). The number and percentage of participants meeting current poverty guidelines for the MMP were determined using the U.S. Department of Health and Human Services (25) poverty guidelines and poverty thresholds published by the U.S. Census Bureau for the NHIS in 2009. Clinical Care Indicators Clinical MMP variables were abstracted from participants' medical records for the year before the interview and included geometric mean CD4+ T-lymphocyte count (0 to 0.199109 cells/L, 0.200 to 0.349109 cells/L, 0.350 to 0.499109 cells/L, or 0.500109 cells/L), plasma HIV RNA viral load (suppression was defined as most recent viral load documented as undetectable, or 200 copies/mL), documented prescription of antiretroviral therapy, and disease stage per CDC criteria (stage 1, no AIDS and nadir CD4+ count 0.500109 cells/L [or 29%]; stage 2, no AIDS and nadir CD4+ count between 0.200 and 0.499109 cells/L [ or 14% to <29%]; or stage 3, AIDS or nadir CD4+ count between 0 and 0.199109 cells/L [or <14%]) (29). Statistical Analysis Prevalence of and Factors Associated With Current Smoking Among Adults With HIV To identify factors associated with current smoking, we used the modified RaoScott chi-square test to measure the bivariate association between each characteristic and current smoking (30). All characteristics that were significant at a P value less than 0.10 were included in the final multivariate logistic model, including age, sex, race or ethnicity, education level, poverty level, homelessness, incarceration, noninjection drug use, binge alcohol use, depression, geometric mean CD4+ count, and viral suppression. For all variables in the model, we computed model-adjusted prevalence differences (shown as percentage points) with 95% CIs among all levels of each characteristic associated with current smoking among adults with HIV using a multivariate logistic regression model with predicted marginal means (31, 32). All analyses were performed using SAS, version 9.3 (SAS Institute), and SAS-callable SUDAAN, version 10.0. 1 (RTI International), and accounted for clustering, unequal selection probabilities, and nonresponse. Comparisons Between Adults With HIV and the U.S. General Adult Population Weighted estimates, percentages, and CIs were determined for current smokers, nonsmokers, and former smokers among adults with HIV (MMP) and the U.S. general adult population (NHIS), stratified by age group, sex, race or ethnicity, education, and poverty level. We did multivariate analyses and tested the association between current smoking and selected characteristics for both populations. Adjusted prevalence estimates (predicted marginal percentages) and prevalence ratios were calculated us