Exploring sentinel conditions and the accrual sequence of multiple long-term condition multimorbidity using birth cohort and primary care data: an exploratory retrospective cohort study

Background Evidence suggests that the sequence of accrual of conditions varies considerably and affects outcomes. We aimed to explore whether sentinel conditions (the first long-term condition occurring in the life course) and accrual sequences of long-term conditions in the development of early onset multimorbidity can be characterised using birth cohort and primary care data. Methods In this retrospective cohort study, we used data from the 1970 British Birth Cohort Study (BCS70) and pseudonymised data from the Care and Health Information Analytics database (CHIA). Age 26 years is the first BCS70 adulthood sweep (round of data collection) age 46 years the most recent (age 50 sweep delayed by COVID-19) and we investigated an exemplar multiple long-term condition multimorbidity (MLTC-M) group with adequate numbers (ie, mental ill-health, backpain, and high blood pressure). In CHIA we defined MLTC-M as two or more (of 21) conditions occurring by age 50. Sequencing identified the timepoint at which sentinel conditions were reported. Findings The BCS70 age 46 years sample comprised of 8581 participants (4427 [52%] women and 4154 [48%] men). For participants who reported the exemplar MLTC-M outcome (n=163), mental ill-health was the sentinel condition for 25% (n=41), with 12% (n=20) reporting mental ill-health at age 26 years. Pain was the second commonest sentinel condition (21%; n=35) with 16% (n=26) reporting pain at age 26 years. 45% (n=74) reported their sentinel condition by age 26. For the exemplar MLTC-M group the most common accrual sequence was mental ill-health and back pain followed by high blood pressure (n=35; 21%). The CHIA sample included 702 265 participants (373 553 [53%] women and 328 712 [47%] men). Out of a total 335 963 people under 50, 65 757 (20%) had MLTC-M. Common sentinel conditions were asthma (44%; n=29 228) and anxiety or depression (37%; n=24 634). Hypertension was a sentinel condition for 4% (n=2580). Interpretation We identified possible sentinel conditions of burdensome MLTC-M in birth cohort and primary care datasets. Continued development of this methodology, drawing together learning from complementary datasets, might help inform the timing and nature of interventions endeavouring to alter health trajectories and preventing the development of MLTC-M. Funding National Institute for Health Research (number NIHR202644).