Step Count: A Consideration for Life Underwriting
How much exercise does it take to be preferred and how can we measure it?
The doctors at CRL published an article in the March issue of On the Risk reviewing the impact of increasing activity levels on mortality in isolation and in combination with laboratory scoring based on NHANES data. We found that higher levels of exercise were associated with lower mortality and the impact was additive, rather than overlapping, with the laboratory score.
Unfortunately, the NHANES activity monitor data from 2003–2005 reported an activity “count” but not the number of daily steps due to missing data; we divided the cohort into quartiles by activity count rather than split by the number of steps or intensity of activity.
Fortunately, a method to impute the daily step count from that NHANES activity data was developed by Benmei Liu, et al. and used recently by Pedro Saint-Maurice, et al. to look at the actual step count and mortality after 10 years. These results were just published in JAMA and extend our findings by allowing use of the commonly available daily step count via fitness monitors instead of the unusable activity count to evaluate mortality risk (JAMA. 2020;323(12):1151–1160).
Using a robust model accounting for age, gender, education, habits, medical history, etc., Saint-Maurice found the relative mortality risk for those aged 40+ decreased as daily steps increased, with limited mortality improvement over 10,000 steps. As compared to those with 12,000 steps daily (19% of the cohort, mean age 51), risk doubled below 8,000 steps (68% of cohort, mean age 57) and tripled below 4,000 steps/day (13% of cohort, mean age 70). There was little change in risk if exercise intensity was also included in the model; this indicates it is the number of steps, not the exercise intensity, that counts.
Based on this data, an insurer could potentially use Fitbit or other fitness monitor data to assess mortality risk with those over 10,000 (or 12,000) daily steps getting credit and those with less than 4,000 steps needing careful underwriting review. However, more granularity by age band is needed first to avoid this becoming a credit for younger age.
About the Author
Michael Fulks, MD, Consulting Medical Director, is board-certified in internal and insurance medicine. After leaving practice, he served as a medical director, creating or editing several underwriting manuals and preferred programs. For the past 13 years, Dr. Fulks has consulted for CRL, participating in its mortality research on individual tests and all laboratory test results, BP and build in combination. He is also involved in the development and implementation of automated screening tools for non-laboratory data.