Stronger Muscles, Healthier Bones: A Case for Secondary Prevention in Bronchiectasis?

The health impacts of bronchiectasis extend beyond the lungs. Cardiovascular comorbidities such as heart failure and hypertension occur more often in people with bronchiectasis compared to healthy controls, and the risk of stroke is higher than in the general population [1, 2]. Diabetes and gastroesophageal reflux are also common [3, 4], as are anxiety and depression, which predict future hospital admissions [5]. Osteoporosis is more prevalent in people with bronchiectasis than in the general population [6]. Both the presence and number of comorbidities have been associated with poor outcome in bronchiectasis, predicting future exacerbations, a more rapid decline in lung function and decreased survival [7, 8]. It is likely that comorbidities interact with the ‘vicious vortex’ of bronchiectasis, amplifying inflammation, reducing resilience to exacerbations, worsening symptoms and further impairing physical function [9]. In a recent research article published in Respirology, Oliveira and colleagues report the results of a longitudinal study that confirms the relationship of bronchiectasis with the comorbidities of poor bone health and reduced muscle function [10]. This study evaluated body composition and muscle function in 71 people with bronchiectasis (10 men) and 92 healthy controls. They report reduced bone mineral density in both men and women with bronchiectasis, with the rate of osteopenia three times higher in women with bronchiectasis compared to their healthy peers. Although this finding is largely confirmatory of previous studies [8, 11], it is highly relevant to patients for evaluating their future health risks related to osteoporosis and fractures. Leg strength was lower in both men and women with bronchiectasis than their healthy counterparts, with reduced leg strength associated with greater decline in functional capacity over 12 months [10]. Women with bronchiectasis had significantly shorter side bridging tests than controls, which is a marker of reduced core (trunk) muscle strength. Reductions in core strength are associated with worse balance and functional performance, and higher rates of falls in older adults [12], suggesting this may also constitute a future health risk. Whilst the study has some limitations, including a small number of male participants and differences in age between people with bronchiectasis and controls, these findings focus our attention on important and potentially modifiable comorbidities in people with bronchiectasis. It is worth considering what our current treatment approaches offer to patients with reduced bone mineral density and peripheral muscle strength, as seen in the current study. Recent clinical guidelines for bronchiectasis indicate that ‘patients at risk should be evaluated for associated osteoporosis’, [13] but the characteristics of an ‘at risk’ patient are not specified. Pulmonary rehabilitation, an effective intervention to improve lower limb muscle function, is recommended for those who are breathless and have impaired exercise capacity [13]. Data presented in the current study [10] suggest that this approach may address reduced muscle strength; the association between this clinical feature and poor functional performance and worse dyspnoea over the longer term highlights the potential importance of this intervention. However, pulmonary rehabilitation does not address low bone mineral density, or reductions in core strength. Indeed, the current pulmonary rehabilitation approach may require modification to address bone strength, including addition of moderate impact exercises such as stamping and low level jumping for those with sufficient balance and without vertebral fractures [14]. Likewise, pulmonary rehabilitation approaches have not traditionally included core strengthening exercises [15]. While the influence of routine airway clearance therapy (recommended in this population) on core strength is unclear, the findings of reduced lateral core endurance in the current study suggest a possible role for this addition to pulmonary rehabilitation. The study of Oliveira and colleagues, considered alongside the data emphasising the importance of comorbidities to long term outcomes [16], should prompt us to consider whether we wait too long to address evolving comorbidities in people with bronchiectasis. For instance, pulmonary rehabilitation delivered once a patient is weak and breathless arguably represents an intervention delivered late in the evolution of peripheral muscle dysfunction. It may be helpful to reflect on what we can learn from the recent re-evaluation of the concept of secondary prevention in cardiac disease [17]. Rather than waiting for symptoms or new cardiac events to occur in high-risk patients and ‘rehabilitating’ them, secondary prevention has been reframed towards optimising cardiovascular health and management of risk factors across the lifespan, to enable patients to live well with chronic disease [17]. This concept has resonance for the optimal management of people with bronchiectasis, many of whom would be considered too functionally able or to have too few symptoms to benefit from pulmonary rehabilitation based on recent guidance [13, 18], which may contribute to low referral rates [19]. The findings of the current study [10] emphasise the value of a comprehensive body composition and muscle strength assessment in people with bronchiectasis. These data challenge us to think beyond traditional approaches to comorbidity management and rehabilitation in bronchiectasis, bringing a secondary prevention lens that addresses future health risks. Stronger muscles and healthier bones may prove fundamental to living well with bronchiectasis. Anne E. Holland receives funding from the National Health and Medical Research Council (GNT 2043192). The authors declare no conflicts of interest.