ABSTRACT
Objective: To determine the association of asthma on health-related quality of life (QoL), productivity, and use of healthcare resources among adults in Brazil. Methods: Data were analyzed from the 2015 Brazil National Health and Wellness Survey, a cross-sectional survey with 12,000 adult respondents. Asthma and control groups were compared with respect to health-related QoL, asthma control, work productivity, and adherence. Generalized linear models were developed to compare asthma-related associations controlling for potential confounding factors. Results: Among respondents, 4.1% (n = 494) reported an asthma diagnosis; those without asthma symptoms were used as the control group (n = 11,487). Regarding asthma control, 51.2% of patients had uncontrolled asthma, 36.4% partially controlled asthma, and 12.3% were fully controlled. Short-acting β2 agonists were the most commonly used class of drugs (38.5%). Approximately 32.4% of asthma patients were considered fully adherent to their treatment. In multivariable analyses, asthma patients presented lower health-related QoL and had more frequent visits with medical healthcare providers (6.1 versus 4.2) emergency room visits (1.0 versus 0.5), and more hospitalizations (0.4 versus 0.2), than control respondents six months prior to the study (p < 0.05). Rates of absenteeism and presenteeism varied between 11.5% and 7.4% (p < 0.05) and 30.4% and 20.9% (p < 0.001) between asthma patients and controls, respectively. Conclusions: Asthma had a negative association on health-related QoL, work productivity, and use of healthcare resources. Excessive use of short-acting β2 agonists and poor treatment adherence reflect poor asthma control and suggest the need to implement new strategies for asthma treatment in Brazil.
Introduction
Asthma is one of the most prevalent chronic diseases in the world. Approximately 235 million people currently suffer from asthma, according to the World Health Organization (WHO) Citation(1), and this figure has been increasing in recent decades. If the current trends continue to rise, it is estimated that there may be an additional 100 million asthmatics globally by 2025 (Citation2, Citation3). In Brazil, more specifically, asthma affects over 6 million adults, according to the National Health Survey (PNS) of the Ministry of Health (MoH) and the Brazilian Institute of Geography and Statistics (IBGE) Citation(4).The resulting prevalence of asthma among Brazilian adults, of 4.4%, agrees with that estimated by the World Health Survey, which included 70 countries Citation(5). PNS also showed that 43% of the affected women and 30% of the affected men had an exacerbation, and 80% of them used an asthma medication in the 12 months prior to the survey Citation(6).
Patients with asthma also experience significant physical and psychological burdens that, consequently, may produce several negative health outcomes. Nocturnal symptoms and sleep pattern disruptions (awakenings) have been reported in 51% and daily symptoms in 56% of patients with asthma in Latin America Citation(7). Asthma negatively influences the quality of life (QoL) of patients; increased psychological disorders such as depression and anxiety have been associated with both mild and severe asthma. (Citation8–10).
Asthma patients also suffer from significant losses in work productivity (e.g., absenteeism, presenteeism, and overall work impairment) and activity impairment outside of the workplace (e.g., problems completing daily activities) (Citation2, Citation3). These individuals also place a heavy burden on the healthcare system, making particularly frequent healthcare provider visits, emergency room (ER) visits, and hospitalizations (Citation7, Citation10). The disease is, therefore, associated with high expenditure that include both direct (e.g., hospital admissions and pharmaceuticals) and indirect costs (e.g., time lost from work and premature death), making asthma one of the most expensive diseases due to the significant healthcare utilization associated with this condition (Citation2, Citation3). The burden of asthma in many countries is of sufficient magnitude to warrant its recognition as a priority disorder in government health strategies. In Brazil, few studies have analyzed the association of asthma on patients’ health-related QoL and their use of healthcare resources, making it difficult to define and develop public health policies in this country that target asthma.
This study investigated the humanistic and economic burden of asthma among adults in Brazil, in terms of the association of asthma on health-related QoL and productivity as well as the use of healthcare resources to diagnose and treat the disease.
Methods
Data source
This study included data from the 2015 Brazil National Health and Wellness Survey (NHWS, n = 12,000), a self-administered, internet-based questionnaire from a large sample of adults living in Brazil (aged ≥18 years). In total, a survey link was sent to 328,496 individuals. All respondents needed to be 18 years and older and we use quote groups for age and gender to be representative of the Brazilian population. All 12,000 respondents in the study met the inclusion criteria, provided informed consent, and completed the questionnaire. To reduce selection bias and increase the representativeness of findings to the adult population in Brazil, the Brazil NHWS was supplemented by Computer-Assisted Web Interviewing to reach people without internet access. A stratified random sampling strategy, with strata by gender and age, was also used (based on data from the International Database of the United States Bureau of the Census). To further correct for any inherent sampling bias with respect to socioeconomic status, custom sampling weights were calculated through a ranking procedure (based on data from the Instituto Brasileiro de Geografia e Estatística) to ensure demographic representativeness. Several peer-reviewed publications have previously compared the NHWS with other governmental sources (Citation11–13). NHWS is reviewed and approved by the Essex Institutional Review Board (IRB) and by local Brazilian IRB (#1.722.654). All respondents provided their informed consent prior to participating and were only known by a unique identifier.
Sample
This analysis focused on individuals with a self-reported asthma diagnosis. Respondents were first asked whether they experienced asthma in the last 12 months. In the case of an affirmative response, respondents were subsequently asked whether they had received an asthma diagnosis by a physician. Only individuals who answered “yes” to both questions were defined as asthma patients in this study. Non-asthma controls were also included in this study (respondents not experiencing asthma). Self-reported asthma subjects who did not have a physician diagnosis were excluded from further analysis.
Covariates
Demographic variables included sex, age, race/ethnicity, marital status, annual household income, education, and socioeconomic status. Regarding socioeconomic status, the classification from the Brazilian Institute for Geography and Statistics (IBGE) was adopted, which is based on household's gross monthly income: class A, above 20 times the National Minimum Salary (NMS); class B, greater than 10 to 20 times the NMS; class C, greater than 5 to 20 times the NMS; class D, greater than 2 to 5 times the NMS; class E, up to 2 times the NMS Citation(14).
Health history variables included smoking habits, alcohol consumption, number of days of vigorous exercise for at least 20 minutes in the past month, and body mass index (BMI). The Charlson Comorbidity Index (CCI), which represents a weighted sum of multiple comorbid conditions predictive of mortality (e.g., HIV/AIDS, diabetes, and congestive heart failure), was also calculated Citation(15). Higher scores indicate a greater comorbid burden.
Additional asthma-related variables were also reported for descriptive purposes. These variables included medication use and medication class, along with years diagnosed with asthma, diagnosing physician type, and causes of asthma attacks.
Outcome variables
This study included responses from the revised Medical Outcomes Study 36-Item Short Form Survey Instrument (SF-36v2), a multipurpose, generic health-related QoL instrument composed of 36 questions Citation(16). Two summary scores are also calculated: physical component summary (PCS) and mental component summary (MCS) scores. For the purpose of the present analyses, PCS and MCS summary scores were utilized as normed scores. This was achieved by transforming the raw scores for the items to a mean of 50 and a standard deviation of 10 for the US population. Scores were interpreted relative to this population average of 50, as well as with other comparison groups of interest. Higher scores indicate better quality of life.
In addition to generating profile and summary PCS and MCS scores, the SF-36v2 was also used to generate a health state utility score. This was achieved through application of the SF-6D algorithm, which takes six domains from the SF-36v2. The SF-6D is a preference-based single index measure for health using general population values Citation(17). The SF-6D index has interval scoring properties and yields summary scores on a theoretical 0–1 scale. Higher scores indicate better QoL.
Work productivity was assessed using the Work Productivity and Activity Impairment General Health (WPAI-GH) questionnaire, a six-item validated instrument consisting of four metrics: absenteeism (the percentage of work time missed because of one's health in the past seven days), presenteeism (the percentage of impairment experienced while at work in the past seven days because of one's health), overall work productivity loss (an overall impairment estimate that is a combination of absenteeism and presenteeism), and activity impairment (the percentage of impairment in daily activities because of one's health in the past seven days) Citation(18). Only respondents who reported being employed full-time, part-time, or self-employed provided data for absenteeism, presenteeism, and overall work impairment. All respondents provided data for activity impairment.
Healthcare utilization was defined by the number of healthcare provider (HCP) visits, the number of emergency room (ER) visits, and the number of times hospitalized during the six months prior to participation. The number of HCP visits included several specialties, such as internist, allergist, neurologist, and general practitioner, among other specialties.
The Asthma Control Test (ACT) Citation(19) and the Morisky, Green, and Levine Medication Adherence Scale (MGLS) were used for analyses that only included asthma respondents. ACT contains five asthma-specific questions to determine respondents’ level of asthma control. Based on the scoring used for this instrument, an ACT score of 19 or less is considered “not well controlled,” scores between 20 to 24 is considered “partially controlled”, and scores 25 are considered “totally controlled.” Adherence to asthma medication was assessed using the 4-item MGLS Citation(20). This scale consists of four questions that were used to assess adherence to asthma prescription medication. Complete adherence was defined as having a score of 4. Non-adherence was defined as having a score of 3 or less.
Statistical Analysis
Descriptive analyses
The underlying distributions of patient characteristics, asthma characteristics, treatment variables, and outcomes for participants were summarized, which informed the appropriateness of the planned approach as well as suggested how different levels of the variables should be grouped for analyses. Categorical variables were reported using counts and percentages. Continuous variables were reported using means and standard deviations.
Bivariate analyses
Bivariate comparisons were conducted that examined the burden of asthma (those diagnosed with the disease were compared with non-asthmatic controls). Demographic and patient characteristic differences between asthma groups were examined. These results served as the basis for identifying covariates for the multivariable models (in addition to variables of theoretical importance). For categorical variables, chi-square tests were used to determine statistically significant differences, whereas one-way ANOVAs were used for continuous variables. P values were provided for omnibus tests (e.g., one-way ANOVA or chi-square).
Multivariable analysis
Respondents living with and without asthma differed in sociodemographic and health characteristics. Outcomes were, therefore, compared using generalized linear models (GLMs) to control for covariates. Covariates were selected after examining significant differences during the bivariate comparisons for asthma versus non-asthma control comparisons. Covariates examined included: age, sex, employment status (not among the three work-related WPAI metrics), education, social economic status (SES), insurance type, alcohol consumption, and CCI. GLMs specifying normal distributions and identity link functions were used for predicting normally distributed outcomes (e.g., health outcome measures) and GLMs specifying negative binomial distributions with log link functions were used for predicting outcome variables with skewed distributions (e.g., work productivity). Normal GLMs (with identity link) are robust models for normal distributions, even those with minor deviations from normality. Negative binomial models correct standard errors of highly skewed distributions to compensate for model under dispersion.
Adjusted means for all outcomes were calculated for each group to help illustrate the pattern of results. Tables depicting the results of regression analyses are also provided.
Results
Bivariate analysis
Among the total 11,981 respondents included in this study, 4.1% (n = 494) reported having an asthma diagnosis; the remaining 95.9% (n = 11,487) of the respondents comprised the non-asthma control group. Asthma respondents were younger (mean age 36.3 versus 40.4 years, p < 0.001), more commonly women (59.9% versus 48.7%, p < 0.001), and reported more comorbidities (CCI mean 0.7 versus 0.3, p < 0.001) than control respondents. Also, compared with controls, asthma respondents tended to be of a higher socioeconomic status, higher education level, be employed (75.5% versus 68.6%), and have private insurance (all p < 0.05). Complete demographic characteristic of asthma and non-asthma respondents are presented in .
Table 1. Demographics by asthma diagnosis.
Respondents with asthma had significantly lower health-related QoL than non-asthma controls on MCS (mean 42.11 versus 46.62), PCS (47.73 versus 51.60), and SF-6D (0.64 versus 0.71) (all p < 0.001). Respondents with asthma also reported significantly higher absenteeism (13.12% versus 7.54%), presenteeism (35.21% versus 21.42%), overall work impairment (40.95% versus 25.27%), and activity impairment (37.85% versus 24.19%) compared to respondents without asthma (all p < 0.05). In addition, asthma respondents had significantly more frequent HCP visits (mean 7.88 versus 4.44), ER visits (1.40 versus 0.59), and hospitalizations (0.67 versus 0.25) relative to non-asthma control respondents (all p < 0.05), during the 6 months prior to participating in the survey. Comparisons of outcome variables (i.e., health-related QoL, work productivity and activity impairment, and healthcare resource use) are reported for asthma and non-asthma respondents in .
Table 2. Health-related quality of life, labor force participation, WPAI, and healthcare resource use by asthma diagnosis.
Out of the 494 asthma respondents, the mean ACT score was 18.48; 51.2% scored ≤19 (partially controlled), 36.4% scored 20–24 (well controlled), and 12.3% scored 25 (total control). A majority of asthma respondents (61.9%) reported currently taking prescription medications to control or treat their condition. Short-acting β2 agonists (SABA) were the most commonly used class of drugs (38.5%), along with ICS/LABA (17.2%) and ICS (12.3%). Approximately 32.4% of asthma patients were considered totally adherent to their treatment regimens. Asthma-related variables were examined for all respondents with self-reported asthma diagnosis in .
Table 3. Descriptive for asthma-related variables for all respondents with asthma diagnosis.
Multivariable analyses
After controlling for covariates, patients with asthma presented lower health-related QoL in the mental (mean 43.8 versus 46.5), physical (48.2 versus 51.6), and health utility score (0.66 versus 0, 71) components; they also had more frequent visits to HCPs (6.1 versus 4.2), and to the ER (1.0 versus 0.5) as well as hospitalizations (0.4 versus 0.2) than the control group in the 6 months prior to the study (all p < 0.005). Rates of absenteeism and presenteeism varied between 11.5% and 7.4% (p < 0.05) and 30.4% and 20.9% (p < 0.001) between patients and control group, respectively. See for full results of these multivariable analyses.
Table 4. Health-related quality of life, healthcare resource use, WPAI, and labor force participation by asthma diagnosis, after controlling for covariates.
Discussion
Asthma represents a significant humanistic and economic burden. It is not only associated with patient-specific impairments, but also with significant costs to society. Asthma is a burden to the healthcare system, the work productivity of patients, as well as to their QoL Citation(3). Results from this study demonstrate the burden of asthma in Brazil and point to a host of likely negative health outcomes for this population.
Asthma patients in Brazil, similar to other parts of the world Citation(21), have relatively poor health-related QoL. These patients are affected not only by the physical consequences of asthma, but also by the mental health consequences associated with asthma that arise from the burden of living with chronic symptoms. They suffer both within the workplace (e.g., absenteeism, presenteeism, and overall work impairment) and outside of the workplace (e.g., impairment completing regular daily activities). This results in asthma patients placing a significant burden on the healthcare system in Brazil, with frequent HCP visits, ER visits, and hospitalizations. Asthma patients and payers in Brazil would benefit from treatment options that help to reduce this burden and associated costs.
Recently, a descriptive study demonstrated that 2,047 people had asthma-related deaths in Brazil (5 deaths/day), with more than 120,000 asthma-related hospitalizations in 2013. Although the numbers of asthma-related deaths and hospital admissions in Brazil have been decreasing from 2008 until 2013 – 10% and 36%, respectively – the absolute numbers are still high, resulting in elevated direct and indirect costs for society Citation(22).
At present, there are several different strategies to treat asthma in Brazil. However, there is a preponderance of SABA use, typically used as “rescue” medication to provide quick relief of asthma symptoms which were also observed in our study. However, treatment with regular doses of ICS alone or in combination with long-acting bronchodilators (LABA) is highly effective in reducing the symptoms and the risk of exacerbations of the disease Citation(23). This suggests that asthma patients in Brazil may need better asthma control and that they should be put on control medication more often, to mitigate the need for rescue medication. Our study noted that most of the asthma patients in this study reported poor control of their asthma and less than one third of them self-reported that they were fully adherent to their treatment regimens. Indeed, poor adherence to maintenance pharmacotherapy is a reality in asthma. Studies confirm that when symptoms worsen, most patients increase SABA use, instead of using controller medication. This behavior might be attributable to several paradoxes in the current treatment paradigm as mild asthma (global initiative for asthma (GINA)-step 1) recommended use of a SABA bronchodilator alone, despite the fact that asthma is a chronic inflammatory disease (Citation23, Citation24), which may be addressed by an anti-inflammatory reliever approach that combines an ICS and fast-acting LABA instead of SABA monotherapy as a reliever therapy).
Future studies should investigate new approaches to treating asthma in Brazil and globally. These studies would be well-advised to focus not only on the implementation of new pharmaceutical treatments designed to alleviate the physical symptoms of asthma, but also on the implementation of techniques that help to reduce the psychological burdens of this condition. Asthma patients need to feel “in control” of their disease. Achieving this goal will require the implementation of effective physiological and psychological treatments. This means that prescribers will need to have better discussions with their patients to prescribe the best treatment option for each individual.
This study has several limitations. Data from the Brazil NHWS are self-reported and cross-sectional in nature, and statements about causality cannot be made from the study results. Also, respondents may not recollect some data correctly.
Conclusion
Asthma had a negative association on health-related QoL, work productivity, and use of healthcare resources. Excessive use of short-acting β2 agonists and poor treatment adherence reflect poor asthma control and suggest the need to implement new strategies for asthma treatment in Brazil. The excessive use of SABA and low adherence to prescription medication can be associated with the poor control of asthma among the respondents of the survey. These results suggest that new strategies aiming the improvement of adherence and the reduction of rescue medicine could result in better asthma management and control.
Conflict of interest
The Brazil NHWS is a survey conducted by Kantar Health. Eloisa de Sá Moreira, Guilherme Silva Julian, Shaloo Gupta and Vicky W Li are full-time employees of Kantar Health during the conduct of the study. AstraZeneca purchased access to the Brazil NHWS data and funded the analysis and preparation of this manuscript. Marcio Penha is a full-time employee of AstraZeneca. Jose Eduardo Delfini Cançado in the last 5 years participated in activities sponsored by the pharmaceutical companies: Achè, AstraZeneca, Boehringer-Ingelheim, Chiesi, GSK, Mantecorp, Novartis and Pfizer. He is also the partner owner of Rede Drogal Farmacêutica Ltda.
Additional information
Funding
References
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