Unveiling the hidden burden: estimating the proportion of undiagnosed depression, hypertension and diabetes - a...

A large proportion of chronic conditions are undiagnosed, preventing early treatment, and leading to poorer outcomes. Understanding how levels of underdiagnosis vary between diseases and population groups over time is crucial for effectively allocating resources and targeting interventions to increase diagnosis rates.

We used two annual national surveys: the Health Survey for England (cross-sectional) and the UK Household Longitudinal Survey, to identify people with diabetes, hypertension and depression. Diagnosed cases were defined as a self-report of being told by a nurse or doctor as having a condition; undiagnosed cases were defined as those where screening tools used in the survey identified clinical signs of the condition but the individual did not self-report a diagnosis. We used logistic regression to estimate the proportion of people with these three conditions who are undiagnosed for 540 population segments defined by age group, sex, deprivation quintile and region between 2011 and 2019. These predicted probabilities were applied to population estimates using microsimulation to model the proportion undiagnosed for each disease in each Clinical Commissioning Group (local health planning areas) in England.

The proportion of people with diabetes and depression who were undiagnosed reduced between 2011 and 2019, with no change in the proportion of hypertensives undiagnosed. For hypertension, people in more deprived areas were less likely to be undiagnosed than those in less deprived areas. The opposite was true for depression. Younger men with hypertension or diabetes were less likely to be diagnosed than older men. Both those aged under 30 and those over 70 with depression were less likely to be diagnosed compared with those aged 30-70.

Strategies aiming to improve undiagnosed hypertension case finding need to understand the reasons for little progress over the past decade. For depression, strategies to increase early diagnosis should prioritise deprived areas. Case finding for all three diseases would benefit from targeting younger age groups.