Multimorbidity: the impact of physical activity and physical function on risk and outcomes

Multimorbidity is recognised internationally as having a serious impact on health outcomes. This thesis aimed to assess the relationships between multimorbidity, physical activity and physical function in order to inform the development and feasibility testing of an appropriate intervention for patients with multimorbidity in primary care. Phase 1 and 2 of the Medical Research Council framework were utilised to guide this research. This thesis comprises three discrete studies; (i) a systematic review, (ii) a prospective cohort study and (iii) an intervention development and feasibility study. The first study, a systematic review, was designed to examine the association between multimorbidity and functional decline. A total of thirty-seven studies were eligible for inclusion (twenty-eight cross-sectional studies and nine cohort studies). The majority of studies (n=31) demonstrated a consistent association between multimorbidity and functional decline. Twelve cross-sectional studies and five cohort studies reported that increasing numbers of conditions were associated with worsening functional decline. A search update conducted for this thesis identified thirteen further studies but synthesis of these studies did not change the original systematic review findings. The available evidence indicates that there is a longitudinal association between multimorbidity and future functional decline, which in turn can lead to worse health outcomes. The second study carried out regression analysis using The Irish Longitudinal Study on Ageing and included participants >50 years with and without multimorbidity over a two year period. Gait speed and grip strength both demonstrated a significant association in those with and without multimorbidity at baseline. Faster gait speed and stronger grip strength was demonstrated to reduce the likelihood of developing new condition/s. Although not statistically significant, increased physical activity levels appeared to be associated with a lower risk of developing multimorbidity. The results of studies one and two along with current best evidence identified in the literature review informed study three. The aim of this third study was to determine the feasibility of an inter-agency physical activity and education programme for patients with multimorbidity in primary care. This programme took place in two Leisure Centres in Dublin. Six sessions were facilitated by a HSE primary care physiotherapist and a Dublin Council fitness instructor and incorporated both exercise and education components. Both subjective and objective outcome measures demonstrated improvements and qualitative analysis indicated that the design of the intervention was appropriate and acceptable. Qualitative themes identified were related to increased confidence and energy and a novel approach to primary care physiotherapy delivery. This thesis demonstrates that physical function is a risk factor for the development of multimorbidity and multimorbidity is associated with functional decline as a health outcome over time. The feasibility study highlights the potential impact of a physical activity and education intervention on multimorbidity and supports progression to a pilot randomised controlled trial.