Digital mobility outcomes to describe real-world walking during recovery from a hip fracture: the Mobilise-D...

The burden of disease caused by fragility fractures, and hip fractures in particular, is significant both from a personal and a societal perspective. Digital technologies such as wearable devices now allow a real-world assessment of walking and physical mobility, describing temporal and spatial measures. Built on a transparent technical validation, the Mobilise-D consortium validated a set of digital mobility outcomes (DMOs) alongside a longitudinal clinical validation study (CVS). This article provides a description of DMOs along with supervised mobility assessment and patient-reported outcomes collected at entry of the CVS study in a sample of home-dwelling participants with a proximal femoral fracture (PFF) recruited within 1 year after surgery.

Participants who underwent surgical treatment for a low-energy PFF were recruited from five sites in three high-income European countries. The first visit encompassed a clinical assessment (~ 3 h) and subsequent 7-day measurement of real-world mobility with a single wearable device. We categorized participants into four recovery phases according to the assessment time after surgery: acute phase (≤ 14 days after surgery, hospital stay), post-acute phase (15-42 days after surgery, mostly rehabilitation), extended recovery phase (43-182 days post-surgery, typically post-discharge at home), and long-term recovery phase (183-365 days post-surgery). All variables were reported descriptively for each phase using mean and standard deviation or median and 25th-75th percentile depending on their distribution.

We enrolled 564 PFF participants (66% women). The mean age was 77.5 (SD 9.6) years. Almost 90% of all participants (n = 505) had a valid digital mobility assessment (wear time of > 12 h per day and at least 3 valid days). DMO domains such as amount (e.g., number of steps), pace (e.g., walking speed), and pattern (bout distribution) demonstrated large differences across phases.

The observed variation in walking amount and pace and pattern across recovery phases indicate that DMOs provide a granular analysis of real-world mobility of hip fracture survivors. When confirmed by longitudinal analyses, including results on minimal important differences, the use of selected DMOs will provide a novel approach for monitoring, predictive modelling, prognosis, stratification, and evaluation of clinical trials and hip fracture services.