The collective dynamics of smoking in a large social network

Socioeconomic Disparities in Health Behaviors

The inverse relationships between socioeconomic status (SES) and unhealthy behaviors such as tobacco use, physical inactivity, and poor nutrition have been well demonstrated empirically but encompass diverse underlying causal mechanisms. These mechanisms have special theoretical importance because disparities in health behaviors, unlike disparities in many other components of health, involve something more than the ability to use income to purchase good health. Based on a review of broad literatures in sociology, economics, and public health, we classify explanations of higher smoking, lower exercise, poorer diet, and excess weight among low-SES persons into nine broad groups that specify related but conceptually distinct mechanisms. The lack of clear support for any one explanation suggests that the literature on SES disparities in health and health behaviors can do more to design studies that better test for the importance of the varied mechanisms.

Socioeconomic Disparities in Health Behaviors

The inverse relationships between socioeconomic status (SES) and unhealthy behaviors such as tobacco use, physical inactivity, and poor nutrition have been well demonstrated empirically but encompass diverse underlying causal mechanisms. These mechanisms have special theoretical importance because disparities in health behaviors, unlike disparities in many other components of health, involve something more than the ability to use income to purchase good health. Based on a review of broad literatures in sociology, economics, and public health, we classify explanations of higher smoking, lower exercise, poorer diet, and excess weight among low-SES persons into nine broad groups that specify related but conceptually distinct mechanisms. The lack of clear support for any one explanation suggests that the literature on SES disparities in health and health behaviors can do more to design studies that better test for the importance of the varied mechanisms.

Social networks and survival after breast cancer diagnosis

INTRODUCTION

Evidence has been inconsistent regarding the impact of social networks on survival after breast cancer diagnosis. We prospectively examined the relation between components of social integration and survival in a large cohort of breast cancer survivors.

METHODS

Women (N=4,589) diagnosed with invasive breast cancer were recruited from a population-based, multi-center, case-control study. A median of 5.6 years (Interquartile Range 2.7-8.7) after breast cancer diagnosis, women completed a questionnaire on recent post-diagnosis social networks and other lifestyle factors. Social networks were measured using components of the Berkman-Syme Social Networks Index to create a measure of social connectedness. Based on a search of the National Death Index, 552 deaths (146 related to breast cancer) were identified. Adjusted hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards regression.

RESULTS

Higher scores on a composite measure of social connectedness as determined by the frequency of contacts with family and friends, attendance of religious services, and participation in community activities was associated with a 15-28% reduced risk of death from any cause (p-trend=0.02). Inverse trends were observed between all-cause mortality and frequency of attendance at religious services (p-trend=0.0001) and hours per week engaged in community activities (p-trend=0.0005). No material associations were identified between social networks and breast cancer-specific mortality.

CONCLUSIONS

Engagement in activities outside the home was associated with lower overall mortality after breast cancer diagnosis.

Emotions as infectious diseases in a large social network: the SISa model

Human populations are arranged in social networks that determine interactions and influence the spread of diseases, behaviours and ideas. We evaluate the spread of long-term emotional states across a social network. We introduce a novel form of the classical susceptible-infected-susceptible disease model which includes the possibility for 'spontaneous' (or 'automatic') infection, in addition to disease transmission (the SISa model). Using this framework and data from the Framingham Heart Study, we provide formal evidence that positive and negative emotional states behave like infectious diseases spreading across social networks over long periods of time. The probability of becoming content is increased by 0.02 per year for each content contact, and the probability of becoming discontent is increased by 0.04 per year per discontent contact. Our mathematical formalism allows us to derive various quantities from the data, such as the average lifetime of a contentment 'infection' (10 years) or discontentment 'infection' (5 years). Our results give insight into the transmissive nature of positive and negative emotional states. Determining to what extent particular emotions or behaviours are infectious is a promising direction for further research with important implications for social science, epidemiology and health policy. Our model provides a theoretical framework for studying the interpersonal spread of any state that may also arise spontaneously, such as emotions, behaviours, health states, ideas or diseases with reservoirs.

Using System Dynamics tools to gain insight into intervention options related to the interaction between tobacco and tuberculosis

Tobacco exposure is an important risk factor for tuberculosis (TB) when considering its effects on population-level disease outcomes. If we hope to gain control over TB globally, we must begin to think ‘outside of the box’ to identify an extended and multi-faceted intervention strategy that is grounded in an understanding of the particular ways in which key risk factors worsen TB. In light of the role of tobacco exposure as an important, identifiable, modifiable, and preventable risk factor for TB, efforts aiming at reducing tobacco use merit inclusion in such a comprehensive TB control program. The goal of this paper is to share the conceptual framework we have developed using System Dynamics methodology, which diagrams the likely effects of tobacco exposure on TB dynamics in a typical low-income country setting. Using this framework as a guide, we leverage an understanding of the likely mechanisms by which tobacco exposure affects TB risk to systematically explore TB control intervention options. We hope that this paper will help inspire new approaches to extend and enhance traditional TB control efforts. We also hope that the conceptual framework will spark further discussion and research on this important and potentially explosive combination of global public health crises.

Effect of teammates on changes in physical activity in a statewide campaign

OBJECTIVE

Most Americans do not meet physical activity recommendations. Statewide campaigns can effectively increase activity levels. Reported herein are physical activity outcomes from Shape Up Rhode Island (SURI) 2007, a statewide campaign to increase steps through team-based competition. Given the importance of social networks in behavior change, this paper focused on the effects of team and team characteristics on activity outcomes.

METHOD

For 16weeks, 5333 adults comprising 652 teams wore pedometers and reported their steps online.

RESULTS

Participants' daily steps increased from 7029(3915) at baseline to 9393(5976) at SURI end (p<0.001). There was a significant intraclass correlation for step change among team members (ICC=0.09); thus, an individual's change in steps was influenced by what team they were on. Moreover, baseline team characteristics predicted individual step change; being on a more active team was associated with greater increases in activity for individual members (p<0.001), whereas being on a team with a broad range of steps was associated with smaller changes in activity for individual members (p=0.02).

CONCLUSION

These findings are the first to suggest that team members influence individual activity outcomes in team-based statewide campaigns. Future research should explore ways to use social network factors to enhance team-based physical activity programs.

Social network structure of a large online community for smoking cessation

OBJECTIVES

We evaluated the social network structure of QuitNet, one of the largest online communities for behavior change, and compared its characteristics to other known social networks.

METHODS

Using modern network analysis methods, we identified QuitNet members who were active during a 60-day period, along with their ties. We then derived multiple subgroups, such as key players and integrators, from connections and communication patterns.

RESULTS

Among 7569 participants, we identified 103,592 connections to other members. Metrics of social network integration were associated with increased likelihood of being female, being older, having been in the system longer, and not smoking.

CONCLUSIONS

The QuitNet community is a large-scale social network with the characteristics required for sustainability of social support and social influence to promote smoking cessation and abstinence. These characteristics include persistence of members over time, heterogeneity of smoking status, and evidence of rich, bidirectional communications. Some of the influential subgroups we identified may provide targets for future network-level interventions.

The behavioral response to personalized genetic information: will genetic risk profiles motivate individuals and families to choose more healthful behaviors?

This report describes the use of information emerging from genetic discovery to motivate risk-reducing health behaviors. Most research to date has evaluated the effects of information related to rare genetic variants on screening behaviors, in which genetic risk feedback has been associated consistently with improved screening adherence. The limited research with common genetic variants suggests that genetic information, when based on single-gene variants with low-risk probabilities, has little impact on behavior. The effect on behavioral outcomes of more realistic testing scenarios in which genetic risk is based on numerous genetic variants is largely unexplored. Little attention has been directed to matching genetic information to the literacy levels of target audiences. Another promising area for research is consideration of using genetic information to identify risk shared within kinship networks and to expand the influence of behavior change beyond the individual.

Reducing HIV risks among active injection drug and crack users: the safety counts program

The efficacy of Safety Counts, a CDC-diffused intervention, was reanalyzed. In a quasi experimental, cross-over design, injection drug users (IDU) and crack users in two neighborhoods were assigned by neighborhood to receive individual Voluntary HIV Counseling and Testing or Safety Counts and 78% were reassessed at 5-9 months. Drug users in the Safety Counts program reported significantly greater reductions in risky sex, crack and hard drug use, and risky drug injection. The more sessions of Safety Counts attended, the greater were the reductions in risky acts. Different analytic decisions result in very different findings for the same intervention. Safety Counts is an effective intervention for IDU and crack users. Analytic decision of intervention outcomes is highly related to evaluations of an intervention's efficacy.

Sources of health information related to preventive health behaviors in a national study

BACKGROUND

Current literature suggests that certain sources of information are used in varying degrees among different socioeconomic and demographic groups; therefore, it is important to determine if specific classes of health information sources are more effective than others in promoting health behaviors.

PURPOSE

This study aims to determine if interpersonal versus mass media sources of health information are associated with meeting recommendations for health behaviors (nonsmoking, fruit/vegetable intake, and exercise) and cancer screening.

METHODS

Multivariable logistic regression models were used to examine the relationship of health information sources (mass media sources including print, TV, Internet; and interpersonal sources including friends and family, community organizations, and healthcare providers) with meeting recommendations for healthy behaviors and cancer screening in the 2005 and 2007 Health Information National Trends Surveys (HINTS). Analyses were conducted in 2009.

RESULTS

In the 2005 HINTS, participants reporting use of print media and community organizations as sources of health information over the past year were mostly likely to meet recommendations for health behaviors. In the 2007 HINTS, utilization of healthcare providers for health information was associated with meeting recommendations for health behaviors, particularly cancer screening.

CONCLUSIONS

Use of print media and interpersonal sources of health information are most consistently associated with self-reported health behaviors. Additional research should explore the relationship of health information sources to clinical outcomes. Social network interventions to promote adoption of health behaviors should be further developed.

Network analysis of team structure in the neonatal intensive care unit

OBJECTIVE

The goal was to examine nursing team structure and its relationship with family satisfaction.

METHODS

We used electronic health records to create patient-based, 1-mode networks of nursing handoffs. In these networks, nurses were represented as nodes and handoffs as edges. For each patient, we calculated network statistics including team size and diameter, network centrality index, proportion of newcomers to care teams according to day of hospitalization, and a novel measure of the average number of shifts between repeat caregivers, which was meant to quantify nursing continuity. We assessed parental satisfaction by using a standardized survey.

RESULTS

Team size increased with increasing length of stay. At 2 weeks of age, 50% of shifts were staffed by a newcomer nurse who had not previously cared for the index patient. The patterns of newcomers to teams did not differ according to birth weight. When the population was dichotomized according to median mean repeat caregiver interval value, increased reports of problems with nursing care were seen with less-consistent staffing by familiar nurses. This relationship persisted after controlling for factors including birth weight, length of stay, and team size.

CONCLUSIONS

Family perceptions of nursing care quality are more strongly associated with team structure and the sequence of nursing participation than with team size. Objective measures of health care team structure and function can be examined by applying network analytic techniques to information contained in electronic health records.

Smoking prevalence and factors associated with smoking status among Vietnamese in California

INTRODUCTION

Vietnamese American men have smoking prevalence rates higher than the general population. We analyzed Vietnamese American smoking behavior by demographic and health-related factors, including some specific to Vietnamese, in the largest tobacco-specific survey yet targeting the Vietnamese population.

METHODS

Using a statewide surname probability sample and computer-assisted telephone interviewing, we surveyed 1,101 Vietnamese men and 1,078 Vietnamese women in California (63.5% participation among successfully contacted eligible individuals) in 2007-2008. We conducted multivariate regression models to analyze the association between Vietnamese male smoking status and demographic and health-related factors.

RESULTS

Among women, <1% were current smokers and <2% were former smokers. Among men, 25% were current and 24% were former smokers. Regression models for Vietnamese men delineated factors associated with both current and former smoking (vs. never smoking): being married, being employed, having lower educational attainment, and consuming alcohol. Other factors associated with current smoking (vs. never smoking) were having no health insurance, having seen a Vietnamese doctor or no doctor visit in the past year, having Vietnamese military or Vietnamese reeducation camp experience, having less knowledge about the harms of smoking, and reporting higher depression symptoms. Increasing age and not being Buddhist were associated with former (vs. never) smoking.

DISCUSSION

Smoking patterns of Vietnamese women and Vietnamese men are significantly different from the general California population. Tobacco control efforts targeting Vietnamese men should include community outreach since current smokers have low health care access, utilization, and knowledge.

Successful cognitive and emotional aging

We review the definitions, determinants, and ways of enhancing successful cognitive and emotional aging. Objective definitions of successful aging based on physical health emphasize outcomes including freedom from disability and disease, whereas subjective definitions center on well-being, social connectedness, and adaptation. Most older people do not meet objective criteria for successful aging, while a majority meet the subjective criteria. Older people with severe mental illness are not excluded from successful aging. The determinants of successful aging include complex interactions of lifestyle behaviors and social environment with genes. Depression interferes with nearly all determinants of successful aging. Evidence-based means of enhancing successful aging include calorie restriction, physical exercise, cognitive stimulation, social support, and optimization of stress. Future directions for successful aging research and implications for geriatric psychiatry are discussed.

Social networks and physician adoption of electronic health records: insights from an empirical study

OBJECTIVE

To study how social interactions influence physician adoption of an electronic health records (EHR) system.

DESIGN

A social network survey was used to delineate the structure of social interactions among 40 residents and 15 attending physicians in an ambulatory primary care practice. Social network analysis was then applied to relate the interaction structures to individual physicians' utilization rates of an EHR system.

MEASUREMENTS

The social network survey assessed three distinct types of interaction structures: professional network based on consultation on patient care-related matters; friendship network based on personal intimacy; and perceived influence network based on a person's perception of how other people have affected her intention to adopt the EHR system. EHR utilization rates were measured as the proportion of patient visits in which sentinel use events consisting of patient data documentation or retrieval activities were recorded. The usage data were collected over a time period of 14 months from computer-recorded audit trail logs.

RESULTS

Neither the professional nor the perceived influence network is correlated with EHR usage. The structure of the friendship network significantly influenced individual physicians' adoption of the EHR system. Residents who occupied similar social positions in the friendship network shared similar EHR utilization rates (p<0.05). In other words, residents who had personal friends in common tended to develop comparable levels of EHR adoption. This effect is particularly prominent when the mutual personal friends of these 'socially similar' residents were attending physicians (p<0.001).

CONCLUSIONS

Social influence affecting physician adoption of EHR seems to be predominantly conveyed through interactions with personal friends rather than interactions in professional settings.

Stem cell tourism and the power of hope

This paper explores the notions of hope and how individual patient autonomy can trump carefully reasoned ethical concerns and policies intended to regulate stem cell transplants. We argue that the same limits of knowledge that inform arguments to restrain and regulate unproven treatments might also undermine our ability to comprehensively dismiss or condemn them. Incautiously or indiscriminately reasoned policies and attitudes may drive critical information and data underground, impel patients away from working with clinical researchers, and tread needlessly on hope, the essential motivator of patients, advocates and researchers alike. We offer recommendations to clinicians and health care providers to help balance the discourse with individuals seeking treatment while guarding against fraud, misconception, and patient harm.

The spread of alcohol consumption behavior in a large social network

BACKGROUND

Alcohol consumption has important health-related consequences and numerous biological and social determinants.

OBJECTIVE

To explore quantitatively whether alcohol consumption behavior spreads from person to person in a large social network of friends, coworkers, siblings, spouses, and neighbors, followed for 32 years.

DESIGN

Longitudinal network cohort study.

SETTING

The Framingham Heart Study.

PARTICIPANTS

12 067 persons assessed at several time points between 1971 and 2003.

MEASUREMENTS

Self-reported alcohol consumption (number of drinks per week on average over the past year and number of days drinking within the past week) and social network ties, measured at each time point.

RESULTS

Clusters of drinkers and abstainers were present in the network at all time points, and the clusters extended to 3 degrees of separation. These clusters were not only due to selective formation of social ties among drinkers but also seem to reflect interpersonal influence. Changes in the alcohol consumption behavior of a person's social network had a statistically significant effect on that person's subsequent alcohol consumption behavior. The behaviors of immediate neighbors and coworkers were not significantly associated with a person's drinking behavior, but the behavior of relatives and friends was.

LIMITATIONS

A nonclinical measure of alcohol consumption was used. Also, it is unclear whether the effects on long-term health are positive or negative, because alcohol has been shown to be both harmful and protective. Finally, not all network ties were observed.

CONCLUSION

Network phenomena seem to influence alcohol consumption behavior. This has implications for clinical and public health interventions and further supports group-level interventions to reduce problematic drinking.

The spread of alcohol consumption behavior in a large social network

BACKGROUND

Alcohol consumption has important health-related consequences and numerous biological and social determinants.

OBJECTIVE

To explore quantitatively whether alcohol consumption behavior spreads from person to person in a large social network of friends, coworkers, siblings, spouses, and neighbors, followed for 32 years.

DESIGN

Longitudinal network cohort study.

SETTING

The Framingham Heart Study.

PARTICIPANTS

12 067 persons assessed at several time points between 1971 and 2003.

MEASUREMENTS

Self-reported alcohol consumption (number of drinks per week on average over the past year and number of days drinking within the past week) and social network ties, measured at each time point.

RESULTS

Clusters of drinkers and abstainers were present in the network at all time points, and the clusters extended to 3 degrees of separation. These clusters were not only due to selective formation of social ties among drinkers but also seem to reflect interpersonal influence. Changes in the alcohol consumption behavior of a person's social network had a statistically significant effect on that person's subsequent alcohol consumption behavior. The behaviors of immediate neighbors and coworkers were not significantly associated with a person's drinking behavior, but the behavior of relatives and friends was.

LIMITATIONS

A nonclinical measure of alcohol consumption was used. Also, it is unclear whether the effects on long-term health are positive or negative, because alcohol has been shown to be both harmful and protective. Finally, not all network ties were observed.

CONCLUSION

Network phenomena seem to influence alcohol consumption behavior. This has implications for clinical and public health interventions and further supports group-level interventions to reduce problematic drinking.

Smokers' reasons for quitting in an anti-smoking social context

OBJECTIVE

To examine the impact of the social denormalization of smoking on smokers' motives for quitting and on subsequent abstinence in a context of intensified anti-smoking measures.

STUDY DESIGN

This study is based on data from 13,746 French smokers who were registered in cessation services nationwide between September 2006 and September 2007.

METHODS

Motives freely reported by smokers on their first visit to a cessation service were explored through open coding. Bivariate methods and multivariate logistic regression analyses were used to assess the association with biochemically validated abstinence at 1 month follow-up.

RESULTS

Motives most frequently expressed by smokers were health concerns (55.0%) and cost of smoking (24.2%), but no significant association was found with abstinence. The highest abstinence rates were achieved by smokers motivated by their social network: 'motivated or pressured by others' (20.9%), 'setting a good example' (20.7%) and 'having a smoke-free social network' (20.3%). Smokers could no longer bear the social constraints of smoking: '[my] friends and family have all quit, [I] smoke outside all alone and feel left out' and 'I no longer want people to say with disgust that I smell of tobacco. I would like to be freed from this addiction because I'm ashamed of smoking, not at home but on the street'.

CONCLUSION

French smokers' motives for quitting reflect a social unacceptability of smoking which has been buttressed by measures intended to reduce tobacco use. Through smoke-free social networks, the denormalization of smoking appears to improve short-term abstinence.

Smoking prevalence and perspectives on smoking on campus by employees in Australian teaching hospitals

BACKGROUND

Cigarette smoking prevalence has been declining over decades in Western countries especially in higher socioeconomic groups. Employees of Australian hospitals span the socioeconomic spectrum, but there are few data on smoking prevalence from these workplaces. Because smoking is a health hazard, some argue that it should be banned on hospital premises, but employees' opinions appear not to have been widely canvassed. Cigarette smoking is a particular problem in hospitals because of the need for prolonged abstinence by immobile patients and the stressors that accompany life-and-death events for patients and/or relatives. The Queen Elizabeth Hospital has had a Stop Smoking Service for >10 years, but how smoking prevalence has changed and how it compares with similar hospitals is unknown.

AIMS

The aims of this study were (i) to determine smoking prevalence by employees of The Queen Elizabeth Hospital and to compare this with employees of other hospitals and (ii) to ascertain employees' perspectives regarding smoking on hospital grounds.

METHODS

Single page questionnaires were forwarded to employees of four South Australian/Northern Territory hospitals enquiring about smoking status, employment category, views about smoking on hospital premises, etc. Responses were voluntary.

RESULTS

Response rates were 39-59%. Smoking prevalence has steadily declined at The Queen Elizabeth Hospital and is now 8.4%. Prevalence at comparator hospitals was approximately double this value. Most staff thought the visibility of smoking was problematic, but support for providing smoking area/s was greater than for a hospital-wide ban.

CONCLUSIONS

The ongoing decline in smoking prevalence at The Queen Elizabeth Hospital is probably the result of the Staff Stop Smoking Service.

The spread of sleep loss influences drug use in adolescent social networks

Troubled sleep is a commonly cited consequence of adolescent drug use, but it has rarely been studied as a cause. Nor have there been any studies of the extent to which sleep behavior can spread in social networks from person to person to person. Here we map the social networks of 8,349 adolescents in order to study how sleep behavior spreads, how drug use behavior spreads, and how a friend's sleep behavior influences one's own drug use. We find clusters of poor sleep behavior and drug use that extend up to four degrees of separation (to one's friends' friends' friends' friends) in the social network. Prospective regression models show that being central in the network negatively influences future sleep outcomes, but not vice versa. Moreover, if a friend sleeps Collapse

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MESH Headings

• Adolescent
• Child
• Friends
• Humans
• Interpersonal Relations
• Longitudinal Studies
• Marijuana Abuse/psychology
• Peer Group
• Persuasive Communication
• Regression Analysis
• Sleep
• Social Conformity
• Social Environment
• Social Support
• Substance-Related Disorders

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Grants

• K01 MH080992 NIMH NIH HHS
• P01 AG031093 NIA NIH HHS
• K01MH080992 NIMH NIH HHS
• P01AG031093 NIA NIH HHS

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Affiliation(s)

Sara C Mednick Department of Psychiatry, University of California San Diego, La Jolla, California, United States of America.
Nicholas A Christakis
James H Fowler

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Alone in the crowd: the structure and spread of loneliness in a large social network

The discrepancy between an individual's loneliness and the number of connections in a social network is well documented, yet little is known about the placement of loneliness within, or the spread of loneliness through, social networks. The authors use network linkage data from the population-based Framingham Heart Study to trace the topography of loneliness in people's social networks and the path through which loneliness spreads through these networks. Results indicated that loneliness occurs in clusters, extends up to 3 degrees of separation, is disproportionately represented at the periphery of social networks, and spreads through a contagious process. The spread of loneliness was found to be stronger than the spread of perceived social connections, stronger for friends than family members, and stronger for women than for men. The results advance understanding of the broad social forces that drive loneliness and suggest that efforts to reduce loneliness in society may benefit by aggressively targeting the people in the periphery to help repair their social networks and to create a protective barrier against loneliness that can keep the whole network from unraveling.

Gender modifies the relationship between social networks and smoking among adults in Seoul, South Korea

OBJECTIVE

To evaluate the interaction of gender with social network mechanisms and smoking behaviors in Seoul, South Korea, where smoking is common among men but not women.

METHODS

During 2002, telephone surveys were completed with 500 adults drawn from a probability sample in Seoul. Respondents described their smoking status, smoking rate (number of cigarettes smoked per day) and social networks by assessing who discouraged or encouraged smoking (smoking support) or smoked (smoking models). Multivariable regressions were used for analyses.

RESULTS

Women encountered significantly less smoking support than men, 88% (95% confidence interval [95% CI], 85-91) versus 70% (95% CI 66-73) net discouragement of smoking in their network. A difference in smoking support from 25 to 75% net discouragement was associated with a 27% (95% CI 9-49) lower probability of smoking among women, significantly stronger (z = 3.18, p < 0.01) than among men who had a 19% (95% CI 8-27) lower probability of smoking. A similar difference in smoking support was associated with male smokers smoking 6.38 (95% CI 0.86-12.30) fewer cigarettes per day, or 2,329 (95% CI 314-4,490) fewer cigarettes per year. The later association could not be observed among women due to the small proportion of female smokers. Smoking models were not significantly associated with any smoking behaviors across genders.

CONCLUSIONS

Social network mechanisms were differentially associated with the high smoking prevalence among men and low prevalence among women and should be targeted by interventions tailored to these differences.

Cooperative behavior cascades in human social networks

Theoretical models suggest that social networks influence the evolution of cooperation, but to date there have been few experimental studies. Observational data suggest that a wide variety of behaviors may spread in human social networks, but subjects in such studies can choose to befriend people with similar behaviors, posing difficulty for causal inference. Here, we exploit a seminal set of laboratory experiments that originally showed that voluntary costly punishment can help sustain cooperation. In these experiments, subjects were randomly assigned to a sequence of different groups to play a series of single-shot public goods games with strangers; this feature allowed us to draw networks of interactions to explore how cooperative and uncooperative behaviors spread from person to person to person. We show that, in both an ordinary public goods game and in a public goods game with punishment, focal individuals are influenced by fellow group members' contribution behavior in future interactions with other individuals who were not a party to the initial interaction. Furthermore, this influence persists for multiple periods and spreads up to three degrees of separation (from person to person to person to person). The results suggest that each additional contribution a subject makes to the public good in the first period is tripled over the course of the experiment by other subjects who are directly or indirectly influenced to contribute more as a consequence. These results show experimentally that cooperative behavior cascades in human social networks.

Disparity in smoking prevalence by education: can we reduce it?

Can an intervention program that is highly effective in reducing the prevalence of an unhealthy behavior in the general population also reduce the disparity among its subgroups? That depends on what measure of disparity is used. Using simple algebraic models, this study demonstrates that disparity measured in terms of relative difference between two groups tends to increase when the prevalence of the behavior is in decline. The study then shows an empirical example, by analyzing the effects of the California tobacco control program on smoking prevalence of two education groups, the lowest (less than 12 years) and the highest (16 years or more). It examines the data from four California Tobacco Surveys covering the years 1996, 1999, 2002, and 2005. The effects of three components of the tobacco control program known to be effective in decreasing prevalence (media, worksite policy, and price) on the two education groups are assessed. The smoking prevalence for the two groups is obtained from these four surveys and a regression line is computed for each education group from 1996 to 2005. Results show that the California program is effective with both low education and high education groups and that the rate of decline in smoking prevalence from 1996 to 2005 is no smaller for the low education group than for the high education group. The paper then discusses that an analysis of disparity based on relative difference, however, could result in misleading recommendations that an intervention like the California tobacco program needs to change from its current whole-population approach to one that focuses on targeting subgroups because it has not reduced disparity. It proposes that research should focus more on increasing the rate of change among less advantage groups and less on the relative disparity compared to some other group.

Helpers program: A pilot test of brief tobacco intervention training in three corporations

BACKGROUND

Quitlines and worksite-sponsored cessation programs are effective and highly accessible, but limited by low utilization. Efforts to encourage use of cessation aids have focused almost exclusively on the smoker, overlooking the potential for friends, family, co-workers, and others in a tobacco user's social network to influence quitting and use of effective treatment.

METHODS

Longitudinal, observational pilot feasibility study with 6-week follow-up survey.

SETTING/PARTICIPANTS

Employees of three national corporations, with a combined target audience of 102,100 employees.

INTERVENTION

The Helpers Program offers web-based, brief intervention training to activate social networks of tobacco users to encourage quitting and use of effective treatment. Helpers was offered from January 10 to March 31, 2008, as a treatment engagement strategy, together with Free & Clear's telephone/web-based cessation services.

MAIN OUTCOME MEASURES

Website utilization, training completion, post-training changes in knowledge and self-efficacy with delivery of brief interventions, referrals to Free & Clear, and use of brief intervention training.

RESULTS

There were 19,109 unique visitors to the Helpers website. Of these, 4727 created user accounts; 1427 registered for Helpers Training; 766 completed training. There were 445 visits to the referral page and 201 e-mail or letter referrals generated. There were 67 requests for technical support. Of follow-up survey respondents (n=289), 78.9% reported offering a brief intervention.

CONCLUSIONS

Offering the Helpers Program website to a large, diverse audience as part of an employer-sponsored worksite health promotion program is both feasible and well accepted by employees. Website users will participate in training, encourage quitting, and refer smokers to quitline services.

The journey to the end of smoking: A personal and population perspective

BACKGROUND

Smoking cessation is best represented as a journey and not a single event. This article chronicles the path of change for the population of smokers in Maryland.

PURPOSE

This study compared the population of ever-smokers in Maryland over three time points (2000, 2002, and 2006) examining how the population of ever-smokers shifted over time.

METHODS

Analysis of process of change and social influence variables conducted using data from the Maryland Adult Tobacco Surveys (MATS) administered in 2000, 2002, and 2006.

RESULTS

Analyses indicated an increasing percentage of ever-smokers (100 lifetime cigarettes) who have successfully quit and maintained cessation for more than 5 years. By 2006, the population of current adult smokers (aged > or =18 years) was smaller but seemed less interested in and able to quit. More 2006 smokers were in earlier stages of change for cessation and not interested in or planning to quit in the near term. Many had unsuccessfully tried to quit, with a substantial minority finding that cessation products found effective in research were not effective for them. Despite past failures, the vast majority expects to quit, has considered quitting, and believes that they will likely succeed eventually. Larger percentages of 2006 smokers are being advised to quit by medical professionals, are accessing empirically supported quit-smoking aids, and have multiple quit attempts. They also smoked every day for more years, smoked as many cigarettes per day, and had environments as filled with smoking as their 2000 and 2002 counterparts.

CONCLUSIONS

Increasing successful cessation would require not only appropriate use of effective products but also successful negotiation of important tasks in the cessation journey. Health literacy and a consumer perspective can help to bridge gaps in the dissemination and effective use of empirically supported treatments.

Understanding disparities in transplantation: do social networks provide the missing clue?

Although the National Organ Transplant Act calls for equity in access to transplantation, scarcity and racial disparities persist. To date, even the most comprehensive models have been unable to adequately explain these racial disparities, leaving policymakers unsure how best to intervene. Previous individual-level analyses, which have implicated risk factors such as race, financial status, cultural beliefs, unemployment, lack of commitment to surgery and lack of continuous access to care, overlook contextual and social network exposures. Social networks present a compelling way to examine cumulative risk clustered across individuals. Social networks have been shown to influence health outcomes and health behaviors through various pathways, including shared social capital, engaging in similar or group risky behaviors, diffusion of information and adopting or propagating social norms. Precursors to chronic kidney disease, including obesity, have been shown to spread through social networks. Social network analysis can reveal shared risks between potential donors and recipients in a given network, clarifying the likelihood of finding an appropriate match through either direct donation or paired exchanges. This paper presents a novel application of social network analysis to transplantation, illustrating implications for disparities and future clinical interventions.

Successful Aging: Focus on Cognitive and Emotional Health

We review the definitions, predictors, and biobehavioral determinants of successful aging, as well as the evidence for and mechanisms of underlying selected interventions to enhance cognitive and emotional health in older adults. Defining successful aging has proven difficult, with discrepancies seen among biomedical, psychological, and lay perspectives. Although consensus is lacking, a number of studies have examined the genetic, lifestyle, and social determinants of operationalized determinants of successful aging; qualitative examinations of the meaning of the construct have also been conducted. The determinants coincide with fundamental aspects of aging. Recent clinical trials suggest that caloric restriction, physical activity, cognitive intervention, stress reduction, and social programs may enhance cognitive and emotional health in older people.

The role of social support and social networks in smoking behavior among middle and older aged people in rural areas of South Korea: a cross-sectional study

Background

Although the number of studies on anti-smoking interventions has increased, studies focused on identifying social contextual factors in rural areas are scarce. The purpose of this study was to explore the role of social support and social networks in smoking behavior among middle and older aged people living in rural areas of South Korea.

Methods

The study employed a cross-sectional design. Participants included 1,057 adults, with a mean age of 60.7 years, residing in rural areas. Information on participants' tobacco use, stress, social support, and social networks was collected using structured questionnaires. The chi-square test, the t-test, ANOVA, and logistic regression were used for data analysis.

Results

The overall smoking prevalence in the study was 17.4% (men, 38.8%; women, 5.1%). Overall, stress was high among women, and social support was high among men. Smokers had high levels of social support (t = -2.90, p = .0038) and social networks (t = -2.22, p = .0271), as compared to non- and former smokers. Those in the high social support group were likely to be smokers (AOR = 2.21, 95% CI 1.15-4.26). Women with moderate social ties were less likely to smoke (AOR = 0.18, 95% CI 0.05-0.61).

Conclusion

There was a protective role of a moderate social network level among women, and a high level of social support was associated with smoking behaviors in rural areas. Findings suggest the need for a comprehensive understanding of the functions and characteristics of social contextual factors including social support and social networks in order to conduct more effective anti-smoking interventions in rural areas.

The increasing complexities of professionalism

Organized medicine's modern-day professionalism movement has reached the quarter-century mark. In this article, the authors travel to an earlier time to examine the concept of profession within the work of Abraham Flexner. Although Flexner used the concept sparingly, it is clear that much of his writing on reforming medical education is grounded in his views on physicians as professionals and medicine as a profession. In the first half, the authors explore Flexner's views of profession, which were (1) empirically (as opposed to philosophically) grounded, (2) case based and comparatively framed, (3) sociological in orientation, and (4) systems based, with professionalism conceptualized as dynamic, evolving, and multidimensional. In the second half, the authors build on Flexner's systems perspective to introduce a complexity science understanding of professionalism. They define professionalism as a complex system, introduce a seven-part typology of professionalism, and explore how the organization of physician work and various flash points within medicine today reveal not one but several competing forms of professionalism at work. The authors then develop a tripartite model of professionalism with analysis at the micro, meso, and macro levels. They conclude with observations on how best to frame professionalism as a force for change in 21st-century medical education. Flexner's reforms were grounded in his vision of two particular types of professional-the physician clinician and the full-time academic physician-scientist. The authors propose reform grounded in professionalism as a complex system composed of competing types.

Psychiatric disorders in smokers seeking treatment for tobacco dependence: relations with tobacco dependence and cessation

OBJECTIVE

The present research examined the relation of psychiatric disorders to tobacco dependence and cessation outcomes.

METHOD

Data were collected from 1,504 smokers (58.2% women; 83.9% White; mean age = 44.67 years, SD = 11.08) making an aided smoking cessation attempt as part of a clinical trial. Psychiatric diagnoses were determined with the Composite International Diagnostic Interview structured clinical interview. Tobacco dependence was assessed with the Fagerström Test of Nicotine Dependence (FTND) and the Wisconsin Inventory of Smoking Dependence Motives (WISDM).

RESULTS

Diagnostic groups included those who were never diagnosed, those who had ever been diagnosed (at any time, including in the past year), and those with past-year diagnoses (with or without prior diagnosis). Some diagnostic groups had lower follow-up abstinence rates than did the never diagnosed group (ps < .05). At 8 weeks after quitting, strong associations were found between cessation outcome and both past-year mood disorder and ever diagnosed anxiety disorder. At 6 months after quitting, those ever diagnosed with an anxiety disorder (OR = .72, p = .02) and those ever diagnosed with more than one psychiatric diagnosis (OR = .74, p = .03) had lower abstinence rates. The diagnostic categories did not differ in smoking heaviness or the FTND, but they did differ in dependence motives assessed with the WISDM.

CONCLUSION

Information on recent or lifetime psychiatric disorders may help clinicians gauge relapse risk and may suggest dependence motives that are particularly relevant to affected patients. These findings also illustrate the importance of using multidimensional tobacco dependence assessments.

Validation of the support provided measure among spouses of smokers receiving a clinical smoking cessation intervention

Studies indicate a positive association between social support and smoking cessation. However, clinic-based interventions designed to increase social support have had limited success. Most studies have relied on only the smoker's perceptions of support received while few have assessed the support provider's report of support delivered. Understanding supportive interactions between support providers and recipients may assist in developing effective support interventions for cessation. The current investigation examined the perceptions of smoking-specific support provided by the spouse of a partner who smokes and was seen for a nicotine dependence consultation. Specifically, we examined spouse reported willingness to help their spouse quit, interest in learning ways to help their spouse quit, and characteristics associated with the provision of smoking-specific supportive behaviors (as assessed via the Support Provided Measure, SPM), in the 2-weeks prior to the consultation. The current investigation also examined the concurrent validity of the SPM with a validated measure of support provided to a smoker, the Partner Interaction Questionnaire (PIQ), accounting for social desirability bias and smoker readiness to change. The sample comprised 84 adult cigarette smokers seen for a clinical smoking cessation intervention and their spouses (N = 84). Results indicate that a high percentage of spouses are willing to help their partner who smokes and interested in learning way to help. As expected, spouses who were females and had never smoked had higher scores on the SPM than males or current smokers. The SPM was significantly correlated with the PIQ positive (r = 0.50, p < 0.01) and negative (r = 0.44, p <0.01) item scales overall and for spouses whose partners reported higher levels of readiness to quit smoking (r = 0.54, p < 0.01; r = 0.50, p < 0.01, respectively). Suggestions for future research are offered.

Estimating peer effects in sexual behavior among adolescents

In this paper we seek to empirically quantify the role of peer social networks in influencing sexual behavior among adolescents. Using data of a nationally representative sample of adolescents we utilize a multivariate structural model with school-level fixed effects to account for the problems of contextual effects, correlated effects and peer selections to purge the potential biases from the estimates of peer influence. Our peer group measures are drawn not only from the nomination of close friends, but also from classmates. Controlling for parent level characteristics, and other demographic parameters, we find that a 10% increase in the proportion of close friends who initiates sex increases the probability that an individual chooses to initiate sex by 5% and a 10% increase in number of sexual partners among close friends increases an individual's sexual partner by 5%. The influence of classmates however, diminishes in magnitude after accounting for unobserved environmental confounders.

Smoking cessation among women with and at risk for HIV: are they quitting?

BACKGROUND

Cigarette smoking is an important risk factor for adverse health events in HIV-infected populations. While recent US population-wide surveys report annual sustained smoking cessation rates of 3.4-8.5%, prospective data are lacking on cessation rates for HIV-infected smokers.

OBJECTIVE

To determine the sustained tobacco cessation rate and predictors of cessation among women with or at risk for HIV infection.

DESIGN

Prospective cohort study.

PARTICIPANTS

A total of 747 women (537 HIV-infected and 210 HIV-uninfected) who reported smoking at enrollment (1994-1995) in the Women's Interagency HIV Study (WIHS) and remained in follow-up after 10 years. The participants were mostly minority (61% non-Hispanic Blacks and 22% Hispanics) and low income (68% with reported annual incomes of less than or equal to $12,000).

MEASUREMENTS AND MAIN RESULTS

The primary outcome was defined as greater than 12 months continuous cessation at year 10. Multivariate logistic regression was used to identify independent baseline predictors of subsequent tobacco cessation. A total of 121 (16%) women reported tobacco cessation at year 10 (annual sustained cessation rate of 1.8%, 95% CI 1.6-2.1%). Annual sustained cessation rates were 1.8% among both HIV-positive and HIV-negative women (p = 0.82). In multivariate analysis, the odds of tobacco cessation were significantly higher in women with more years of education (p trend = 0.02) and of Hispanic origin (OR = 1.87, 95% CI = 1.4-2.9) compared to Black women. Cessation was significantly lower in current or former illicit drug users (OR = 0.42 95% CI = 0.24-0.74 and OR = 0.65, 95% CI = 0.49-0.86, respectively, p trend = 0.03) and women reporting a higher number of cigarettes per day at baseline (p trend < 0.001).

CONCLUSIONS

HIV-infected and at-risk women in this cohort have lower smoking cessation rates than the general population. Given the high prevalence of smoking, the high risk of adverse health events from smoking, and low rates of cessation, it is imperative that we increase efforts and overcome barriers to help these women quit smoking.

The relative health burden of selected social and behavioral risk factors in the United States: implications for policy

OBJECTIVES

We sought to quantify the potential health impact of selected medical and nonmedical policy changes within the United States.

METHODS

Using data from the 1997-2000 National Health Interview Surveys (linked to mortality data through 2002) and the 1996-2002 Medical Expenditure Panel Surveys, we calculated age-specific health-related quality-of-life scores and mortality probabilities for 8 social and behavioral risk factors. We then used Markov models to estimate the quality-adjusted life years lost.

RESULTS

Ranked quality-adjusted life years lost were income less than 200% of the poverty line versus 200% or greater (464 million; 95% confidence interval [CI]=368, 564); current-smoker versus never-smoker (329 million; 95% CI=226, 382); body mass index 30 or higher versus 20 to less than 25 (205 million; 95% CI=159, 269); non-Hispanic Black versus non-Hispanic White (120 million; 95% CI=83, 163); and less than 12 years of school relative to 12 or more (74 million; 95% CI=52, 101). Binge drinking, overweight, and health insurance have relatively less influence on population health.

CONCLUSIONS

Poverty, smoking, and high-school dropouts impose the greatest burden of disease in the United States.

Distinguishing influence-based contagion from homophily-driven diffusion in dynamic networks

Node characteristics and behaviors are often correlated with the structure of social networks over time. While evidence of this type of assortative mixing and temporal clustering of behaviors among linked nodes is used to support claims of peer influence and social contagion in networks, homophily may also explain such evidence. Here we develop a dynamic matched sample estimation framework to distinguish influence and homophily effects in dynamic networks, and we apply this framework to a global instant messaging network of 27.4 million users, using data on the day-by-day adoption of a mobile service application and users' longitudinal behavioral, demographic, and geographic data. We find that previous methods overestimate peer influence in product adoption decisions in this network by 300-700%, and that homophily explains >50% of the perceived behavioral contagion. These findings and methods are essential to both our understanding of the mechanisms that drive contagions in networks and our knowledge of how to propagate or combat them in domains as diverse as epidemiology, marketing, development economics, and public health.

Smoker-free workplace policies: developing a model of public health consequences of workplace policies barring employment to smokers

A marked shift in tobacco-related workplace health promotion intervention involves the adoption of policies barring employment to smokers. We discuss the potential public health consequences of these policies on those affected-smokers, their families, the surrounding community and society at large. We find a lack of published evidence evaluating the effectiveness and consequences of these policies. By developing a model of policy effects, we outline possible unintended consequences. With such large gaps in the evidence base and the potential for deleterious consequences, we argue for increased discussion about the use of smoker-free employment policies as a public health intervention and for increased engagement of employers by the public health community in worksite health promotion.

Best practices for smoking cessation: implications for employer-based programs

Tobacco use and smoking continue to be one of the most important potentially preventable health problems of the 21st century. A large number of studies published in the peer-reviewed literature now inform much of our employer-based programming efforts. Worksite settings and health plan member populations are served primarily through worksite-based interventions, which are examined in this literature review. As a consequence, a number of important resulting "best practices" for smoking cessation efforts with employed populations are presented for consideration in this edition of The Art of Health Promotion.

Estimating peer effects in adolescent smoking behavior: a longitudinal analysis

PURPOSE

To empirically quantify the role of peer social networks in explaining smoking behavior among adolescents. We follow adolescents over time to examine whether the role of adolescent peers persists in affecting individual behaviors as adolescents transition into adulthood.

METHODS

Using longitudinal data of a nationally representative sample of adolescents we use a multivariate structural model with school-level fixed effects to account for the problems of contextual effects, correlated effects, and peer selections to purge the potential biases from the estimates of peer influence. Our peer group measures are drawn not only from the nomination of close friends but also from classmates. Smoking prevalence among the peer groups were constructed using the peers' own reports of their cigarette consumption.

RESULTS

Controlling for parent level characteristics and other demographic parameters, we find that a 10% increase in the proportion of classmates who smoke will increase the likelihood of smoking by more than 3%. Also, an increase in smoking rates among an individual's close friends by 10% will increase the likelihood of smoking by 5%. We find evidence to show that the influence of close friends from adolescence years continue to have an impact on smoking propensities even when a transition into adulthood is made.

CONCLUSIONS

Our findings support the literature reporting that peer effects are important determinants of smoking even after controlling for potential biases in the data and that these effects persist into adulthood. Effective policy aimed at reducing smoking rates among adolescents would consider these long-lasting peer effects.