Medicine out of hospital

Tens of millions of people now carry devices that count steps, measure heart rate and estimate sleep continuously, and large cohorts — UK Biobank's accelerometer sub-study, the All of Us programme, several national cohorts — have begun to link those signals to outcomes. The early findings are strong and simple: step counts and measured activity predict mortality better than questionnaires, and the relationship is graded down to low levels of activity. Beyond that the evidence is mixed. Whether continuous monitoring improves outcomes when acted on has been tested mostly in single conditions with modest results; the populations that wear devices are healthier and richer than those that do not, which limits what can be generalised; and the measures themselves — sleep staging, heart-rate variability — are validated unevenly.

The health systems have moved regardless. England has built thousands of "virtual ward" beds since the pandemic, in which people who would have been admitted are monitored at home; hospital-at-home services on the same model exist in Australia, Spain and the United States; and the trials that preceded them, mostly small, found similar mortality and readmission to inpatient care for selected patients at lower cost. Whether that holds at scale, for the patients actually enrolled rather than those selected for trials, is being evaluated now, with early English results mixed on admissions avoided. Telehealth consultations, which rose tenfold in the pandemic, have settled at a level well above 2019 with little outcome evidence either way.

For population statistics the question is whether device data can supplement surveys of physical activity and health, and the offices are only beginning to ask it.

Status

emerging

Direction

mixed

Would change our view

A population-representative cohort with device data and mortality follow-up; a trial in which monitoring changed a hard outcome at scale; or an evaluation of virtual wards with mortality and readmission as outcomes across a whole system.

Trackers

Gaps

Representative samples rather than volunteers; device data from Japan, Korea and the Nordic countries linked to registers; validation of the derived measures against clinical ones; evaluation of care-at-home models outside England.