Factors associated with multimorbidity and its link with poor blood pressure control among 223,286 hypertensive patients.

Multimorbidity has become the norm worldwide as populations age. It remains, however, infrequently researched. This study evaluated factors associated with multimorbidity in a predominantly Chinese hypertensive population. We included all adult patients prescribed their first antihypertensive agents in the entire public sector in Hong Kong from a validated database. Multimorbidity was defined as having one or more medical conditions (cardiovascular diseases; respiratory diseases; diabetes or impaired fasting glucose; renal disease) in addition to hypertension. We studied the prevalence of multimorbidity and performed multinomial regression analyses to evaluate factors independently associated with multimorbidity. 223,286 hypertensive patients (average age of 59.9 years, SD 17.6) were included. The prevalence of having 0, 1 and ≥ 2 additional conditions was 59.6%, 32.8% and 7.5%, respectively. The most common conditions were cardiovascular disease (24.2%) and diabetes (23.0%), followed by respiratory disorders (14.6%) and renal disease (10.9%). Older age (>50 years), male sex, lower household income, receipt of social security allowance and suboptimal blood pressure control (>140 mmHg or >90 mmHg; >130 mmHg or >80 mmHg for diabetes patients; AOR = 3.38-4.49) were significantly associated with multimorbidity. There exists a synergistic effect among these variables as older (≥ 70 years), male patients receiving security allowance had substantially higher prevalence of multimorbidity (19.9% vs 7.5% among all patients). Multimorbidity is very common in hypertensive patients and its prevalence increased markedly with the presence of risk factors identified in this study. Hypertensive patients with multimorbidities should receive more meticulous clinical care as their blood pressure control tends to be poorer.