Perceived risk and outcome expectancy on the practice of home infusion technique in a hemophilia population

This study described home infusion techniques and practices, measured the perceived risk of HIV and hepatitis transmission to self and others, and measured the outcome expectancy of following risk reduction guidelines for 90 hemophilia patients and/or their infusion assistants. It also assessed general knowledge of HIV and hepatitis information for the same population.^ The study subjects were hemophilia patients or their infusion assistants from the Gulf States Hemophilia Center in Houston, the El Paso Satellite Hemophilia Clinic in El Paso, or Texas members of the Women Outreach Network of the National Hemophilia Foundation (WONN) group. Each subject was interviewed either by telephone or in person. The questionnaire used was developed for the study and consisted of 60 items. These items assessed general demographics for the patients and assistants, including questions about their training to do infusions as well as the actual practices, measured perceived personal risk for the transmission of HIV or hepatitis to the assistants, perceived risk of transmission of HIV or hepatitis to others for assistants and self-infusers, and the outcome expectancy for following recommended risk reduction guidelines also for both groups.^ The theoretical framework used assumed that perceived risk and outcome expectancy would be predictive of behavior. The findings did not support this theory. Instead, the findings suggest that infusion behavior is habitual in nature; most respondents perform exactly the same behavior for every infusion. Since none of the variables selected were predictive of the compliance behavior for home infusion the teaching method should be directed towards mastery learning, or learning that will incorporate the correct behavior into a habitual pattern of home infusion. ^

A proposed application of the attributable risk technique in the assessment of unmet need among newly organized populations

In the midst of health care reform, and as health care organizations reorganize to provide more cost-effective healthcare, the population is being shifted into new healthcare delivery systems such as health insurance purchasing alliances, and health maintenance organizations. These new models of delivery are usually organized within resource restricted and data limited environments. Health care planners are faced with the challenge of identifying priorities for preventive and primary care services within these newly organized populations (Medicare HMO, Medicaid HMO, etc.). The author proposes a technique usually employed in epidemiology--attributable risk estimation--as a planning methodology to establish preventive health priorities within newly organized populations. Illustrations of the methodology are provided utilizing the Texas 1992 population. ^

An evaluation of a behavioral change intervention for smokeless tobacco use

During the last three decades considerable attention has been placed on the reduction of tobacco use due to cigarette smoking. During this time, studies have been funded and programs have been developed that focus on both prevention and cessation of cigarette smoking. This intense focus has led to a significant decline in cigarette smoking. But now, use of another form of tobacco--smokeless tobacco--is gaining in popularity.^ In 1989, the National Cancer Institute funded a research study at The University of Texas M. D. Anderson Cancer Center, called Working Well, to develop, implement, and evaluate worksite health promotion programs aimed at reducing cancer risks. As part of this program, a behavioral intervention for smokeless tobacco use was developed. This dissertation evaluates the impact of that behavioral change intervention for smokeless tobacco use.^ Data collected during the Working Well program were analyzed to determine the effect of the intervention. The primary outcomes analyzed were smokeless tobacco cessation, stages of change movement, and prevalence. The secondary outcomes analyzed included the prediction of smokeless tobacco use, stage movement, and cessation. Primary outcome analyses were conducted using the worksite as the unit of analysis, while the secondary analyses were conducted using the individual as the unit of analysis.^ Approximately 20% of the male population used smokeless tobacco. Results of intervention analyses indicate that the Working Well program produced no intervention effect on any of the primary outcomes. At the final observation, the experimental worksites achieved a quit rate of 27%, while the control worksites achieved a quit rate of 26% (P = 0.78). Stage movement for the experimental worksites was 49%, while the control worksites experienced stage movement of 43% (P = 0.20). The results of the analyses on smokeless tobacco prevalence followed the same pattern. Predictors of smokeless tobacco use, cessation, and stage movement were also identified.^ Based on the results found in this study, smokeless tobacco should remain a research priority. Future research should focus on smokeless tobacco use, including the identification of the determinants of smokeless tobacco use and the development of measures and effective intervention strategies. ^

Behavioral facets of cancer chemoprevention trials

Few studies have explored factors related to participation in cancer chemoprevention trials. The purpose of this dissertation was to conduct investigations in this emerging field by studying aspects of participation at three phases of cancer chemoprevention trials: at enrollment, during a placebo run-in period, and post-trial. In all three studies, subjects had a history of cancer and were at high risk of recurrence or second primary tumors.^ The first study explored correlates of enrollment in a head and neck cancer chemoprevention trial by comparing participants and eligible nonparticipants. Of 148 subjects who met the trial's preliminary eligibility criteria, 40% enrolled. In multivariate analysis, enrollment was positively associated with being male (OR 2.36) and being employed (OR 2.73). The most commonly cited reason for declining participation among nonparticipants was transportation.^ The second study examined outcomes of an eight-week placebo run-in period in a head and neck cancer chemoprevention trial. Of 391 subjects, 91.3% were randomized after the run-in. Adherence to drug capsules ranged from 0% to 120.3% (mean $\pm$ SD, 95.8% $\pm$ 15.1). In multivariate analysis, the main variable predicting run-in outcome was race; white subjects were 3.45 times more likely to be randomized than non-white subjects. Subjects with Karnofsky scores of 100 were 2.13 times more likely to be randomized than were subjects with lower scores.^ The third study used post-trial questionnaires to assess subjects' (n = 64) perceptions of participation in a cancer chemoprevention trial. The most highly rated trial benefit was the perception of potential colon cancer prevention, and the most troublesome barrier was erroneous billing for study visits. Perceived benefits were positively associated with interest in participating in future trials of the same (p = 0.05) and longer (p = 0.02) duration, and difficulty with trial pills and procedures was inversely related to interest in future placebo-controlled trials (p = 0.01).^ These are among the first behavioral studies to be completed in the rapidly growing field of cancer chemoprevention. Much work has yet to be done, however, to advance our understanding of the complex issues relating to chemoprevention trial participation. ^

Macular edema in Hispanics with non-insulin dependent diabetes mellitus in Starr County, Texas: Prevalence, incidence and risk factors

This project is based on secondary analyses of data collected in Starr County, Texas from 1981 till 1991 to determine the prevalence, incidence and risk factors for macular edema in Hispanics with non-insulin-dependent diabetes in Starr County, Texas. Two studies were conducted. The first study examined the prevalence of macular edema in this population. Of the 310 diabetics that were included in the study 22 had macular edema. Of these 22 individuals 9 had clinically significant macular edema. Fasting blood glucose was found to be significantly associated with macular edema. For each 10 mg/dl increase in fasting blood glucose there was a 1.07 probability of an increase in the risk of having macular edema. Individuals with fasting blood glucose $\ge$200 mg/dl were found to be more than three times at risk of having macular edema compared to those with fasting blood glucose $<$200 mg/dl.^ In the second study the incidence and the risk factors that could cause macular edema in this Hispanic population were examined. 240 Hispanics with non-insulin-dependent diabetes mellitus and without macular edema were followed for 1223 person-years. During the follow-up period 27 individuals developed macular edema (2.21/100 person-years). High fasting blood glucose and glycosylated hemoglobin were found to be strong and independent risk factors for macular edema. Participants taking insulin were 3.9 times more at risk of developing macular edema compared to those not taking insulin. Systolic blood pressure was significantly related to macular edema, where each 10 mmHg increase in systolic blood pressure was associated with a 1.3 increase in the risk of macular edema.^ In summary, this study suggests that hyperglycemia is the main underlying factor for retinal pathological changes in this diabetic population, and that macular edema probably is not the result of sudden change in the blood glucose level. It also determined that changes in blood pressure, particularly systolic blood pressure, could trigger the development of macular edema.^ Based on the prevalence reported in this study, it is estimated that 35,500 Hispanic diabetics in the US have macular edema. This imposes a major public health challenge particularly in areas with high concentration of Mexican Americans. It also highlights the importance of public health measures directed to Mexican Americans such as health education, improved access to medical care, and periodic and careful ophthalmologic examination by ophthalmologists knowledgeable and experienced in the management of diabetic macular edema. ^

THE INCIDENCE OF PELVIC ENDOMETRIOSIS IN ROCHESTER, MINNESOTA, 1970-1979

The primary objectives of the study were to measure the incidence of pelvic endometriosis among white females of reproductive age (15-49 years) in Rochester, Minnesota, during the period 1970-1979 and to determine the risk of endometriosis by age, marital status, nun status, and educational attainment in this population. An historical prospective design was used. Incident (newly diagnosed) cases were identified from community medical records, and person-years of risk in the study population were estimated from census data.^ Almost two-thirds of the incident cases had surgically verified endometriosis, while the remainder were diagnosed by clinical findings alone. Incidence rates were prepared first with histologically confirmed cases only and then with the successive inclusion of less certain cases: surgically visualized, clinically probable, and clinically possible. On this basis, overall incidence rates were 108.8 to 246.9 newly diagnosed cases per 100,000 person-years. The incidence of pelvic endometriosis was lowest for women 15-19 years of age, increased markedly through age 44, and then declined for women 45-49 years of age. A significantly greater risk of pelvic endometriosis in never married women was detected only when the numerator was limited to histologically confirmed cases. Among never married women 20-49 years of age, no significant difference in the risk of pelvic endometriosis by nun status was detected, but a trend toward a lower incidence in nuns was observed. Women with education beyond high school had a significantly higher incidence of endometriosis than women with less education.^ Cases in the four diagnostic groups differed greatly by age and marital status but were similar with respect to virtually all other characteristics, once age differences were considered. Reproductive history characteristics described included: age of menarche; history of menopause; total pregnancies; ages of first pregnancy, marriage, and sexual intercourse; years from menarche to first intercourse; years of ovulatory cycling; difficulty becoming pregnant; and delay of the first pregnancy by choice. How these characteristics of incident cases differ from those of women free of endometriosis needs to be studied in future research. ^

ECONOMIC ANALYSIS OF THE DEMAND FOR PRESCRIPTION MEDICINE IN THE UNITED STATES

The purpose of this study was to understand the role of principle economic, sociodemographic and health status factors in determining the likelihood and volume of prescription drug use. Econometric demand regression models were developed for this purpose. Ten explanatory variables were examined: family income, coinsurance rate, age, sex, race, household head education level, size of family, health status, number of medical visits, and type of provider seen during medical visits. The economic factors (family income and coinsurance) were given special emphasis in this study.^ The National Medical Care Utilization and Expenditure Survey (NMCUES) was the data source. The sample represented the civilian, noninstitutionalized residents of the United States in 1980. The sample method used in the survey was a stratified four-stage, area probability design. The sample was comprised of 6,600 households (17,123 individuals). The weighted sample provided the population estimates used in the analysis. Five repeated interviews were conducted with each household. The household survey provided detailed information on the United States health status, pattern of health care utilization, charges for services received, and methods of payments for 1980.^ The study provided evidence that economic factors influenced the use of prescription drugs, but the use was not highly responsive to family income and coinsurance for the levels examined. The elasticities for family income ranged from -.0002 to -.013 and coinsurance ranged from -.174 to -.108. Income has a greater influence on the likelihood of prescription drug use, and coinsurance rates had an impact on the amount spent on prescription drugs. The coinsurance effect was not examined for the likelihood of drug use due to limitations in the measurement of coinsurance. Health status appeared to overwhelm any effects which may be attributed to family income or coinsurance. The likelihood of prescription drug use was highly dependent on visits to medical providers. The volume of prescription drug use was highly dependent on the health status, age, and whether or not the individual saw a general practitioner. ^

TECHNOLOGY ASSESSMENT: SMALL-VOLUME INFUSION PUMPS

"Technology assessment is a comprehensive form of policy research that examines the short- and long-term social consequences of the application or use of technology" (US Congress 1967).^ This study explored a research methodology appropriate for technology assessment (TA) within the health industry. The case studied was utilization of external Small-Volume Infusion Pumps (SVIP) at a cancer treatment and research center. Primary and secondary data were collected in three project phases. In Phase I, hospital prescription records (N = 14,979) represented SVIP adoption and utilization for the years 1982-1984. The Candidate Adoption-Use (CA-U) diffusion paradigm developed for this study was germane. Compared to classic and unorthodox curves, CA-U more accurately simulated empiric experience. The hospital SVIP 1983-1984 trends denoted assurance in prescribing chemotherapy and concomitant balloon SVIP efficacy and efficiency. Abandonment of battery pumps was predicted while exponential demand for balloon SVIP was forecast for 1985-1987. In Phase II, patients using SVIP (N = 117) were prospectively surveyed from July to October 1984; the data represented a single episode of therapy. The questionnaire and indices, specifically designed to measure the impact of SVIP, evinced face validity. Compeer group data were from pre-SVIP case reviews rather than from an inpatient sample. Statistically significant results indicated that outpatients using SVIP interacted socially more than inpatients using the alternative technology. Additionally, the hospital's education program effectively taught clients to discriminate between self care and professional SVIP services. In these contexts, there was sufficient evidence that the alternative technology restricted patients activity whereas SVIP permitted patients to function more independently and in a social lifestyle, thus adding quality to life. In Phase III, diffusion forecast and patient survey findings were combined with direct observation of clinic services to profile some economic dimensions of SVIP. These three project phases provide a foundation for executing: (1) cost effectiveness analysis of external versus internal infusors, (2) institutional resource allocation, and (3) technology deployment to epidemiology-significant communities. The models and methods tested in this research of clinical technology assessment are innovative and do assess biotechnology. ^

AN INVESTIGATION OF THE RELIABILITY AND VALIDITY OF THE CENTER FOR EPIDEMIOLOGIC STUDIES DEPRESSION SCALE IN THREE ETHNIC GROUPS

Epidemiologic studies of mental disorder have called attention to the need for identifying untreated cases and to the inadequacies of the instruments available for this purpose. Accurate case ascertainment devices are the basis of sound epidemiology. Without these, neither case classification nor analytic studies of risk factors is possible.^ The purpose of this research was to examine the reliability and validity of an instrument designed to measure depressive symptoms in community populations--the Center for Epidemiologic Studies Depression Scale (CES-D Scale). Two particular foci of the study were whether or not the scale had the same statistical structure across three ethnic groups and whether or not the magnitude and pattern of rates of symptoms for these groups were affected by one source of response error, that due to response tendencies. The effects of age and education on the pattern and magnitude of rates also were examined. In addition, the reliability and validity of the measures of response tendencies were assessed.^ The study population consisted of residents of Alameda County, California. A stratified sample of approximately 700 whites, blacks and Mexican-Americans was interviewed in the summer and fall of 1978.^ The results of the analysis indicated that the scale was reliable and measured a similar content domain across the three ethnic groups. The unadjusted sex- and ethnic-specific rates of depressive symptoms showed an ethnic pattern for both sexes: rates for whites were lowest, those for Mexican-Americans were highest, and those for blacks were intermediate. Measures of response tendencies--need for social approval, trait desirability, and acquiescence--affected the magnitude of the rates for most comparisons. Likewise, the pattern of rates changed somewhat from that originally observed. The one fairly consistent observation was that rates for Mexican-American women were higher than those for the other two female subgroups in most of the comparisons. These results must be considered in the context of the reliability and validity assessment of the measures of response tendencies which indicated the tenuousness of these measures.^ Age affected the ethnic pattern of rates for men in an inconsistent way; for women, Mexican-Americans continued to have higher rates than whites or blacks in all age categories. Education affected the magnitude of rates for women but not for men. For both men and women, Mexican-Americans had higher rates in all educational strata. Rates for women showed an inverse association with education while those for men did not. ^

THE RELATIONSHIP BETWEEN SERUM CHOLESTEROL AND CANCER INCIDENCE IN THE POPULATION OF THE HYPERTENSION DETECTION AND FOLLOW-UP PROGRAM

The relationship between serum cholesterol and cancer incidence was investigated in the population of the Hypertension Detection and Follow-up Program (HDFP). The HDFP was a multi-center trial designed to test the effectiveness of a stepped program of medication in reducing mortality associated with hypertension. Over 10,000 participants, ages 30-69, were followed with clinic and home visits for a minimum of five years. Cancer incidence was ascertained from existing study documents, which included hospitalization records, autopsy reports and death certificates. During the five years of follow-up, 286 new cancer cases were documented. The distribution of sites and total number of cases were similar to those predicted using rates from the Third National Cancer Survey. A non-fasting baseline serum cholesterol level was available for most participants. Age, sex, and race specific five-year cancer incidence rates were computed for each cholesterol quartile. Rates were also computed by smoking status, education status, and percent ideal weight quartiles. In addition, these and other factors were investigated with the use of the multiple logistic model.^ For all cancers combined, a significant inverse relationship existed between baseline serum cholesterol levels and cancer incidence. Previously documented associations between smoking, education and cancer were also demonstrated but did not account for the relationship between serum cholesterol and cancer. The relationship was more evident in males than females but this was felt to represent the different distribution of occurrence of specific cancer sites in the two sexes. The inverse relationship existed for all specific sites investigated (except breast) although a level of statistical significance was reached only for prostate carcinoma. Analyses after exclusion of cases diagnosed during the first two years of follow-up still yielded an inverse relationship. Life table analysis indicated that competing risks during the period of follow-up did not account for the existence of an inverse relationship. It is concluded that a weak inverse relationship does exist between serum cholesterol for many but not all cancer sites. This relationship is not due to confounding by other known cancer risk factors, competing risks or persons entering the study with undiagnosed cancer. Not enough information is available at the present time to determine whether this relationship is causal and further research is suggested. ^

AN ASSESSMENT OF THE RELATION OF CANCER MORTALITY RATES AND SOURCES OF DRINKING WATER IN TEXAS

The geographic distribution of average annual age-adjusted mortality rates (1964-1976) for four types of cancer (all cancer sites combined, gastrointestinal, urinary, and lung cancer) were compared by sources of drinking water for 254 Texas counties and county rural areas and 301 Texas cities. Exposure variables considered were surface versus ground water, public water supplies versus individuals wells, and trihalomethane levels in municipal water supplies. Each general source of "surface" and "ground" water was further divided by aggregating ground water using areas by aquifers and surface water using study areas by river basins. Potential confounding variables taken into account included median education, employment in cancer risk industries, population mobility, ethnicity, and urbanicity. A pattern of higher and lower cancer mortality rates was found for populations using some aquifers and river basins. Further study is required to determine whether the differences in cancer mortality rates that were observed are related to drinking water content or are coincidental with differences in personal characteristics which could not be taken into account in this ecologic study design. ^

INFECTION: ITS ECOLOGICAL DETERMINANTS AMONG CHILDREN IN NORTHERN CHILE

In developing countries, infection and malnutrition, and their interaction effects, account for the majority of childhood deaths and chronic deficits in growth and development. To promote child health, the causal determinants of infection and malnutrition and cost-effective interventions must be identified. To this end, medical examinations of 988 children (age two weeks to 14 years) living at three altitudes (coastal < 300m; sierra (TURN) 3,000m; and altiplano > 4,000m) in Chile's northermost Department of Arica revealed that 393 (40%) of the youngsters harbored one or more infections. When sorted by region and ethnicity, indigenous children of the highlands had infection rates 50% higher than children of Spanish descent living near the coast.^ An ecological model was developed and used to examine the causal path of infection and measure the effect of single and combined environmental variables. Family variables significantly linked to child health included maternal health, age and education. Significant child determinants of infection included the child's nutrient intake and medical history. When compared to children well and free of disease, infected youngsters reported a higher incidence of recent illness and a lower intake of basic foodstuffs. Traditional measures of child health, e.g. birth condition, weaning history, maternal fertility, and family wealth, did not differentiate between well and infected children.^ When height, weight, arm circumference, and subcapular skinfold measurements were compared, infected children, regardless of age, had smaller arm circumferences, the statistical difference being the greatest for males, age nine to eleven. Height and weight, the traditional growth indices, did not differentiate between well and infected groups.^ Infection is not determined by a single environmental factor or even a series of variables. Child health is ecological in nature and cannot be improved independent of changes in the environment that surrounds the child. To focus on selected child health needs, such as feeding programs or immunization campaigns, without simultaneously attending to the environment from which the needs arose is an inappropriate use of time, personnel, and money. ^

ASSOCIATIONS AND INTERRELATIONSHIPS OF SOCIOECONOMIC STATUS, BEHAVIORAL FACTORS AND BIOLOGICAL FACTORS WITH BIRTH WEIGHT

Although the influences of socioeconomic, behavioral and biological factors on birth weight have been extensively studied, most studies have been limited to clinical populations. This study examines such relationships in a national probability sample, the National Health and Nutrition Examination Survey of 1971-1974. The study sample consisted of 2161 white children and 812 black children, aged 1 to 5 years. Analyses were performed on a subsample consisting of 753 white and 138 black children whose mothers were also selected into the survey. Detailed analyses examined interrelationships among socio-economic, behavioral and biological factors by means of multiple regression and partial correlation procedures in the white population. These analyses were not carried out among blacks because of an observed clustering bias introduced in the black subsample that hampered generalization to the US population.^ The results among the whites indicated that the biological factors of maternal height, maternal weight, maternal size (weight/height('2)), maternal age and sex of child were independently related to birth weight and were also interrelated with socioeconomic factors such as family income, education of the mother and education of the head of the household. The joint effect was significantly associated with birth weight.^ Mothers' dietary practices represented the behavioral factors. Selected nutrients from the mothers' 24-hour dietary recall were used to develop indices of dietary quality. Dietary quality was significantly interrelated with socioeconomic status, biological factors and birth weight.^ The findings of this study suggest that smaller, younger mothers of lower socioeconomic status and female children were significantly associated with lower birth weight. The findings also suggest that dietary quality is a mediating factor among socioeconomic status and biological factors in that mothers with more financial and educational resources have better dietary practices. Such mothers may also practice other health behaviors that would prevent having a low birthweight baby. This dissertation contributes primarily to the further conceptualization and empirical testing of the interrelationships among socioeconomic, behavioral and biological factors with respect to birth weight. ^

AN ECONOMIC ANALYSIS OF THE DEMAND FOR CARE IN A FREE-STANDING EMERGENCY CENTER

Free-standing emergency centers (FECs) represent a new approach to the delivery of health care which are competing for patients with more conventional forms of ambulatory care in many parts of the U.S. Currently, little is known about these centers and their patient populations. The purpose of this study, therefore, was to describe the patients who visited two commonly-owned FECs, and determine the reasons for their visits. An economic model of the demand for FEC care was developed to test its ability to predict the economic and sociodemographic factors of use. Demand analysis of other forms of ambulatory services, such as a regular source of care (RSOC), was also conducted to examine the issues of substitution and complementarity.^ A systematic random sample was chosen from all private patients who used the clinics between July 1 and December 31, 1981. Data were obtained by means of a telephone interview and from clinic records. Five hundred fifty-one patients participated in the study.^ The typical FEC patient was a 26 year old white male with a minimum of a high school education, and a family income exceeding $25,000 a year. He had lived in the area for at least twenty years, and was a professional or a clerical worker. The patients made an average of 1.26 visits to the FECs in 1981. The majority of the visits involved a medical complaint; injuries and preventive care were the next most common reasons for visits.^ The analytic results revealed that time played a relatively important role in the demand for FEC care. As waiting time at the patients' regular source of care increased, the demand for FEC care increased, indicating that the clinic serves as a substitute for the patients' usual means of care. Age and education were inversely related to the demand for FEC care, while those with a RSOC frequented the clinics less than those lacking such a source.^ The patients used the familiar forms of ambulatory care, such as a private physician or an emergency room in a more typical fashion. These visits were directly related to the age and education of the patients, existence of a regular source of care, and disability days, which is a measure of health status. ^

Investigating the effects of the 2007 Texas tobacco tax increase on the smoking behavior of adults

Smoking is major cause of premature mortality and morbidity in the United States. The health consequences of tobacco usage are increasingly concentrated in minority and lower socioeconomic groups. One of the most effective means of deterring tobacco consumption and generating revenue to fund prevention activities is the levying of excise taxes. In 2007 the state of Texas increased the excise tax on cigarettes by $1.00 per pack. This study sought to determine if there was a significant effect on smoking prevalence in the state by examining Behavioral Risk Factor Surveillance System (BRFSS) data for two years leading up to the tax increase-2005 and 2006- and two years post tax increase -2007 and 2008. Results were compared against a chi square distribution and three multiple logistic regression models were created to adjust for race/ethnicity, age, education and income. Results from this study show that there was not a significant decrease in smoking prevalence for most of the groups stratified by age, income and ethnicity. There was not a significant decrease in the younger adults aged 18-34 by income, ethnicity, or education. Smoking prevalence increased for some groups, e.g., Hispanic females. In the regression models, the tax effect was not significant. While overall prevalence decreased by 9%, there were not significant reductions among non-White or Hispanic survey participants. Taxed sales dropped by approximately 17% according to the Texas Comptroller. Without BRFSS data measuring daily cigarette consumption among current smokers, now not assessed, it is impossible to determine whether the discrepancy in reported prevalence and taxes sales is attributable to consumption of fewer cigarettes among smokers or tax avoidance.^