Determinants of asthma among adults in Tigray, Northern Ethiopia: a facility-based case-control study

Introduction

Asthma is a condition in which airways get narrow and swell and produce extra mucus that can make breathing difficult and trigger coughing, wheezing, and shortness of breath. Asthma is a public health concern affecting millions of productive age groups in developed and developing countries with prevalence rates 1 to 21% among adults (Asher & Pearce, 2014; Enilari & Sinha, 2019).

Asthma affects roughly 334 million people worldwide, and if the current trend continues, there will be a 25% increase in asthma cases over the next fifteen years, leading to numerous annual deaths. Asthma causes less than 1% of deaths, which is a low mortality rate compared to other chronic diseases but it causes 250,000 potentially avoidable fatalities worldwide (Ellwood et al., 2017).

Asthma was first identified as a disease in hospital OPD visits and admissions in Ethiopia after the middle of the 1970s, according to the EPHA and FMOH 2014-2016 National Strategic Action Plan (NSAP) (Ethiopian Public Health Association, 2012; Federal Ministry of Health Ethiopia, 2016). Despite limited documented research on the determinants of asthma, prevalence studies found varying prevalence rates. A systematic review of major NCDs epidemiology (Misganaw et al., 2014) as well as recent prevalence, and associated factor studies in Debrebirhan and Jimma town reported 29.6% and 4.9% rates, respectively (Tefereedgn & Ayana, 2018; Shine, Muhamud & Demelash, 2019).

Both in developed and developing nations, asthma causes considerable economic and social costs. The majority of the burden of asthma manifests as disability in those under 45 years old, but in older people, inadequate long-term care and a delay in receiving assistance during an attack are linked to premature mortality. As a result, asthma has significant negative economic, medical, and social effects on the patient, their family, and society, evidenced by job and school absenteeism, frequent ER visits, hospitalizations, and even mortality at any age (Cruz et al., 2010; Enilari & Sinha, 2019; Alem, Gebeyehu & Arega, 2020).

In order to achieve optimal asthma control, GINA and other stakeholders developed and routinely reviewed fixed international scientific treatment recommendations. Asthma was also listed as a priority in Ethiopia’s National Strategic Action Plan for preventing and controlling NCDs (Federal Ministry of Health Ethiopia, 2016). The document on the clinical and programmatic management of significant NCDs was also created in Ethiopia in 2016 based on the progress of the achievement of the global 2025 NCDs objective (Federal Ministry of Health Ethiopia, 2016). Asthma is still a public health concern in many regions of the world despite the local and international efforts done to reduce the disease’s burden.

Designing, organizing, and putting into practice prevention efforts to lessen the burden of asthma can be based on an evidence-based understanding of the modifiable determinants of the disease development. To the best of our knowledge, there have not been enough studies on the determinants of developing asthma in Ethiopia, particularly in the Tigray region. Therefore, this study was carried out to identify determinants of asthma among adult patients attending in the OPD of Tigray hospitals. This study can be used as a baseline for interested researchers, policymakers, planners, and implementers working on asthma prevention and control programs.

Material and Methods

Results

Discussion

The current study identified different factors that are probably associated with the onset of asthma in the study area. Urban residence, low monthly income, history of skin allergy, family history of asthma, house dust or smoke exposure, lifetime firewood use, house dampness, owning pets and being physically inactive were significant predictors for the development of asthma. On the other hand door opening while cooking was a protective factor for asthma.

Urban residence was positively associated with asthma. The relationship could be urban dwellers might get exposed to air pollution from automobiles, industrial emissions, and solid and liquid wastes that can trigger bronchial irritation. As a result, the bronchial irritation caused due to outdoor air pollution may mimic asthma in susceptible individuals. Asthma may have been caused as a result of this condition. This study agrees with the studies done in Canada, India, Uganda, and Ethiopia (Aggarwal et al., 2006; Santos et al., 2018; Kirenga et al., 2019; Shine, Muhamud & Demelash, 2019). On the other hand, the present study result was inconsistent with other studies done in Canada and India, where the risk of having asthma was significantly higher in respondents who were residing in rural areas than their counterparts (Gupta & Mangal, 2006; Crighton, Wilson & Senécal, 2010). This variation might be due to the difference in the study subjects’ lifestyle where the study in Jaipur district India suggested that the higher prevalence of asthma was observed in rural areas related to hookah smoking.

In the current study, the odds of getting asthma among respondents with a monthly income less than 1,000 ETB were more than twice higher than their peers. The reason for this is that people with low monthly wages have fewer alternatives for implementing asthma prevention techniques (Agrawal, Pearce & Ebrahim, 2013). This result agrees with studies conducted in Korea, Sweden, Australia, New York, and Ethiopia (Claudio, Stingone & Godbold, 2006; Hedlund, Eriksson & Rönmark, 2006; Kozyrskyj et al., 2010; Choi et al., 2012).

This study revealed that the odds of getting asthma among respondents who have a history of skin allergy were higher as compared to their counterparts. The association could be several immunological and structural skin cells, including T cells, are stimulated by allergens due to the manifestation of skin allergy. These cells release mediators for the stimulation of cell-mediated responses and the production of allergen-specific antibodies. In response to the particular allergen that may causes asthma, the presence of a skin allergy could trigger bronchial inflammation. Similar associations have been also observed in several studies (Aggarwal et al., 2006; Gupta & Mangal, 2006; Rémen et al., 2012; Kirenga et al., 2019).

The current finding showed that having a family history of asthma increases the odds of getting asthma. There are two probable explanations for this association: either inherited factors or a shared environment amongst family members contribute to the pathophysiology of asthma. This implies that a susceptible individual with a family history of asthma has to minimize the environmental conditions that can trigger the development of asthma signs and symptoms. This result agreed with the study done in Colombia, India, Uganda, and Ethiopia (Aggarwal et al., 2006; Liu et al., 2009; Gonzalez-Garcia et al., 2015; Wortong, Chaiear & Boonsawat, 2015; Shine, Muhamud & Demelash, 2019; Abebe et al., 2021).

In this study, door opening while cooking was found to be a protective factor for asthma. Not opening the door could result in poor ventilation of the house, which could cause respiratory tract congestion due to the possibility of regular usage of firewood/coal. This result suggests that to promote a healthy indoor air exchange while cooking requires door opening. This result is consistent with a study done in Pakistan and Ethiopia (Khan et al., 2014; Abebe et al., 2021). On the other hand, this study is inconsistent with the study done in the Netherlands which mentioned that there was no relationship between kitchen ventilation and asthma (Willers et al., 2006). This discrepancy may result from differences in the frequency and length of door openings during cooking, methodology, and study population. For instance, the study from the Netherlands recruited five-year-old children who had no connection with cooking.

In the present study, an association was observed among respondents who used lifetime firewood/coal as a source of energy for cooking. The connection between the two can be explained by the likelihood that burning wood inside the house can cause irritation to the bronchi that might mimic the onset of asthma. This is because various inflammatory substances are released, such as cytokines, and chemokines, which can cause inflammatory damage and increase bronchial reactivity. It can even get worse cooking food with firewood/coal without opening a door due to indoor air pollution. Repeated exposure to coal or wood smoke irritates the lungs and increases the risk of developing asthma. This result is similar to Nigeria, Peru, USA and Ethiopia (Thacher et al., 2013; Gaviola et al., 2016; Enilari & Sinha, 2019; Abebe et al., 2021) but inconsistent with the studies done in Colombia, China, India, and Uganda (Barry et al., 2010; Guddattu, Swathi & Nair, 2010; Jie et al., 2016; Kirenga et al., 2019). This variation could be due to difference in the sample size, cooking space, door opening frequency, and duration of exposure to firewood/coal.

The odds of getting asthma among respondents who have dampness or molds inside their houses were higher compared to those who do not have dampness or molds inside their houses. The association between mold and asthma can be explained by the fact that indoor molds can trigger allergic reactions mediated by immunoglobulin E, toxic reactions brought on by non-specific inflammatory reactions and irritating volatile organic compounds produced by microbes or cell walls (Hwang, Liu & Huang, 2011). The association can be also explained if molds and humidity are inside the house which may produce unpleasant odors that irritate the respiratory system and may precipitate the onset of asthma in a susceptible individual. This finding is similar to the study done in Taiwan, USA, Singapore and Netherlands (Tham et al., 2007; Hwang, Liu & Huang, 2011; Weinmayr et al., 2013; Xiao et al., 2021).

The odds of getting asthma among respondents who possessed pets were higher compared to those who do not possess pets. This may be because the respondents may not know the risks of pet keeping for asthma which was mentioned in research done in China and Bulgaria where the percentage of people who had avoidance behavior towards pets was low. The low avoidance behavior of pets was similar in this study where 93.6% of the pets were allowed to stay in the respondent’s bedroom. This finding was similar to the study done in Finland, China, and Congo (Jaakkola et al., 2002; Takkouche et al., 2008; Jie et al., 2016; Obel et al., 2017; Luo et al., 2018). On the other hand, this finding was inconsistent with the study done in Japan which reported that having pets was a protective factor (Taniguchi & Kobayashi, 2023). This variation could be due to difference in study population, pet ownership definition and duration of pet ownership which was not considered in the current study.

The odds of getting asthma among physically inactive respondents were higher compared to those who were physically active. This finding was consistent with a study done in America and Sweden (Eijkemans et al., 2012; Agrawal, Pearce & Ebrahim, 2013; Jerning et al., 2013; Garcia-Aymerich et al., 2014; Ebell, Marchello & O’connor, 2017) but inconsistent with the study done in Spain (Benet et al., 2011; Ebell, Marchello & O’connor, 2017). This variation might be due to the difference in study populations and measurement tools used for physical inactivity.

Conclusion

The study found various modifiable determinants of adult asthma in the Tigray region. Keeping the door open while cooking was found to be a protective factor. Asthma has been associated with urbanization, low income, history of allergic disorders, exposure to house dust or smoke, use of firewood, ownership of pets and sedentary lifestyle. Health professionals should screen and inform patients who are at higher risk to asthma. Moreover, community and personal sensitization through information, education, and communication strategies about the identified determinant factors and implement preventive steps like opening a door while cooking, being physical active and minimizing firewood use might help to lower the risk of asthma among adults. Policymakers, researchers and clinicians involved in the field will be interested in a larger prospective studies.

Limitation

This study shares the weakness of the case-control study which is recall bias that may exaggerate or reduce the association. Moreover, respondents were asked about both disease outcomes and risk factors at a time. So it is difficult to conclude the direction of causality in this study.

Supplemental Information