Introduction
The number of people suffering from multimorbidity, defined as the simultaneous existence of two or more chronic health conditions within an individual, is currently on the rise, especially in primary care.1 A study that was conducted in Japan showed that the prevalence of multimorbidity is 29.9% in adult residents, with the proportion rising to 62.8% in those aged 65 or older.2
Depression, one of the leading diseases contributing to global disease burden, needs to be considered if we are to understand the best way to care for patients with multimorbidity.3 Chronic physical conditions and symptoms are consistently associated with an increased tendency towards depressive symptoms.4 5 Furthermore, previous studies have shown that depression is two to three times more likely in people with physical multimorbidity compared with people without physical multimorbidity or those who have no chronic physical condition.6 Although in these studies the associations of the total number of chronic health conditions with depression have been investigated, such an index may be too crude to fully understand how multimorbidity affects depressive symptoms. Non-random cluster patterns of chronic physical conditions may have different associations with depressive symptoms. Indeed, these multimorbidity patterns have been attracting attention from researchers and healthcare providers who aim to understand the complex nature of multimorbidity and improve the quality of care for patients with multimorbidity. Recent studies have used statistical approaches such as factor analysis to identify complex patterns of multimorbidity.1 7–10
Whether physical multimorbidity patterns have different relationships with depressive symptoms has not been investigated before. In the present study, we aim to examine the associations among the different physical multimorbidity patterns with depressive symptoms.