Progression of multiple long-term conditions (multimorbidity) in England: a population-based descriptive study of...

Incidence of multiple long-term conditions (MLTCs), or multimorbidity, is inconsistently defined and infrequently reported at whole-population level. We aimed to measure the MLTC incidence and progression rates, examining the interaction between ethnicity and socioeconomic deprivation, using routinely collected health-care data covering the adult population of England, UK.

Using the National Segmentation Dataset, we measured incidence of 28 long-term conditions, that align with the Delphi consensus for the definition of MLTCs in research, among adults aged 20 years and older in England between April 1, 2022, and March 31, 2023. We defined MLTC progression rate as the incidence of events in which disease burden progresses through the acquisition of one or more long-term conditions. We measured this over a longer 6-year period, identifying adults aged 20 years and older acquiring their first or second long-term condition between April 1, 2017, and March 31, 2018, and measuring the MLTC progression rate to March 31, 2023. Cox proportional hazard regression was used to examine sociodemographic associations.

Among 49·6 million adults between April 1, 2022, and March 31, 2023, conditions occurring as a first condition with the highest incidence were depression (1088 [95% CI 1085-1092] cases per 100 000 person-years), hypertension (885 [882-888]), cancer (525 [522-528]), diabetes (464 [462-466]), asthma (440 [438-443]), osteoarthritis (394 [392-396]), coronary heart disease (252 [250-254]), and cerebrovascular disease (196 [194-197]). These accounted for 78·5% of all first conditions. Of 1 092 728 people acquiring their first and 535 661 their second conditions between April 1, 2017, and March 31, 2018, median follow-up time was 5·16 years (IQR 2·58-5·50) and 4·41 years (IQR 1·33-5·41), respectively. Progression rate per 100 person-years was 8·56 (95% CI 8·53-8·58) from one condition to two or more conditions and 13·60 (13·55-13·65) from two conditions to three or more conditions. Among those aged 40-49 years at baseline, the progression rate from two to three or more conditions (9·48 [9·36-9·60]) was 46% higher than one to two or more conditions (6·48 [6·42-6·53]). Proportional hazards models showed progression from one to two or more conditions was highest in the most deprived quintile (hazard ratio [HR] 1·37 [1·36-1·39]; p<0·0001 compared with least deprived) and the Black ethnic group (HR 1·19 [1·11-1·29]; p<0·0001 compared with the White ethnic group), and lower in females (HR 0·95 [0·94-0·95]; p<0·0001 compared with males). Negative interaction coefficients between Black ethnicity and most deprived quintile (index of multiple deprivation quintile 1) showed a reduced association between progression and deprivation within the Black ethnic group (HR 0·78 [0·72-0·85]; p<0·0001).

In this whole-population study of adults in England, eight long-term conditions (ie, depression, hypertension, cancer, diabetes, asthma, osteoarthritis, coronary heart disease, and cerebrovascular disease) account for the majority of the first conditions people acquire. The presence of existing conditions is associated with higher MLTC progression rate. Socioeconomic deprivation is strongly associated with progression, apart from in the Black ethnic group in which progression is high across all intersectional ethnicity and deprivation subgroups, highlighting the importance of intersectional approaches in public health policy and research.

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