We conducted a cross-sectional study investigating the association between multimorbidity and HrQoL in middle-aged patients at a primary care setting in Singapore. In the study, participants with multimorbidity had significantly lower domain-specific HrQoL scores (EQ5D UI) but not global HrQoL scores (VAS). Specifically, participants reported more problems with the domain of pain/discomfort.
Middle-aged patients with multimorbidity had lower EQ5D UI, and is in keeping with the findings from other studies.9,11,29 Multimorbidity increases the disease burden and affects one’s HrQoL. Additionally, patients with multimorbidity are more likely to experience higher treatment burden which includes polypharmacy, adjustment to major lifestyle changes, constant monitoring of one’s own health status, and navigation of a complex healthcare system.30−32 Middle-aged adults also often have multiple financial and care-giving responsibilities33 which may be overwhelming for them to balance these responsibilities with their own healthcare needs.
Although patients with multimorbidity had lower EQ5D VAS in our study, the association was not statistically significant. This is in contrast to other studies in the primary care34 and general populations35 that reported an inverse relationship between multimorbidity and VAS scores. The EQ5D UI is based on the participants’ selection of one out of three responses to each of the five EQ5D domains that is weighted by general public preferences. In contrast, the VAS is derived from the participants’ self-indication of their general health for that day. Compared to the choice-based UI, the VAS measures a broader construct of the individual’s health which is not confined to the five specific domains and is more reflective of the individual’s perception of his or her own general health state.36 This study suggested that while multimorbidity was associated with poorer HrQoL compared to those without multimorbidity, as measured by a composite of pain, physical functioning, and mental wellbeing in the middle-aged participants, it was not associated with the general health state. When considering their general health state, the participants could have perceived their chronic conditions as mild, with little impact on their lives. While illness perception has been associated with HrQoL in single diseases,37,38 its influence on HrQoL in patients with multimorbidity is not well studied. Further studies are required to understand the association of patients’ illness perceptions with multimorbidity and their HrQoL.
Another interesting finding in our study was the significant association between multimorbidity and the EQ5D domain of pain/discomfort. The domain of pain/discomfort has the highest percentage of reported problems in our study and this is similar to other studies.12,29,34,39 Chronic pain is a common, complex, and challenging condition and the extent to which multimorbidity is associated with chronic pain in the middle-aged population is unknown. A cross-sectional analysis of the elderly MultiCare Cohort Study sample found that chronic pain, as measured by the Graded Chronic Pain Scale40 was largely associated with chronic lower back problems.19 In our study, we were not able to distinguish if participants who reported problems to pain/discomfort had chronic or acute pain, neither were we able to determine the cause(s) of the participants’ pain/discomfort. One may suffer from pain caused by the side-effects of medications, or from the discomfort caused by the disease(s). Moreover, chronic pain is strongly influenced by demographic and psychosocial factors.41 Future studies may be undertaken to evaluate the factors contributing to chronic pain and HrQoL in middle-aged patients with multimorbidity. This can contribute to subsequent interventions to improve HrQoL in this population.
It is important to note that our sample is slightly older compared to other middle-aged primary care populations,3,15,23 with most of our patients aged between 55–64 years old. This is reflective of the middle-age distribution at our centre as well as the fast-ageing Singapore population.21 Within our population participants below 50 years had poorer HrQoL compared to those 60 years and above, a finding similar to that by Peters et al.42 Possible explanations include the burden of additional responsibilities such as work or caring for children and elderly parents, and the higher likelihood of younger people reporting mental health problems which may have affected the EQ5D UI.42 However, the adaptability of patients to the onset of new conditions and different chronic disease trajectories may change with time.42 We also found that participants living with others had lower HrQoL compared to those living alone. Middle-aged patients with multimorbidity may face additional stress from caring for dependents, who would most likely be staying with them. Prazeres et al43 also showed that living arrangement may affect both the physical and mental components of HrQoL in patients with multimorbidity.
Strengths and limitations
This study has a few limitations. Firstly, the cross-sectional nature does not allow establishment of causal relationships. Secondly, as the study was done at a single polyclinic, there was slight over-representation of Chinese and under-representation of Malays and Indians compared to the national population. Thirdly, the data collected were self-reported and there may be under or over-reporting of chronic medical conditions.44,45
The strengths of our study include the administration of the study questionnaires in multiple languages to maximize sample representativeness, and the selection of a validated HrQoL measure with local HrQoL weights. In addition, our study used a systematic randomized sampling method to select potential participants as an attempt to better represent the primary care population..