On October 27th, the United States Preventive Services Task Force (USPSTF) issued a draft recommendation to extend colorectal cancer screening to individuals 45-49 years of age (Grade B recommendation). Assuming the public comment period does not uncover any surprises, the recommendation will be finalized by the end of the year. The recommendation includes the group’s modeling of benefits and harms with the proposed screening strategy. Compared to our current screening recommendations (screening individuals 50-75 years of age), the new recommendation will add 22-27 additional life-years at a cost of 0.2-2 additional gastrointestinal and cardiovascular complications per 1000 individuals screened.
Given the different ways to undergo colon cancer screening, the Task Force did not model the cost-effectiveness of their broader screening recommendations. Regardless of the screening approach, the recommendation will not be cost-saving. The recommendation led me to consider how I might go about prioritizing other preventive interventions to improve health. I might start with examining the most common causes of avoidable disability and premature death. Others have already done this work.
A disability-adjusted life year (DALY) is the sum of years of life lost (typically compared to living to age 75) and years lost due to disability. Unlike a quality-adjusted life year (QALY) that measures the benefit with or without a medical intervention (individual measure), DALY is a societal measure and measures the total burden of a risk factor or disease. In 2004, the World Health Organization published a set of disability weights used in the Global Burden of Disease (GBD) studies.
The Institute for Health Metrics and Evaluation recently added the GBD 2019 results to its online tool. Here are the top ten causes of DALYs for all Americans in 2019:
| Cause | DALYs (95% CI) |
|---|---|
| Ischemic heart disease | 8,948,089 (8,384,078-9,405,294) |
| Low back pain | 5,697,152 (4,114,139-7,474,690) |
| Chronic obstructive pulmonary disease | 5,021,538 (4,512,795-5,344,914) |
| Opioid use disorders | 4,776,381 (3,965,843-5,701,860) |
| Tracheal, bronchus and lung cancer | 4,186,491 (4,004,696-4,325,919) |
| Diabetes mellitus type 2 | 4,127,419 (3,314,503-5,112,093) |
| Other musculoskeletal disorders* | 3,708,318 (2,691,090-4,914,367) |
| Falls | 2,243,263 (1,786,850-2,840,949) |
| Major depressive disorder | 2,242,301 (1,552,734-3,056,520) |
| Age-related and other hearing loss | 2,187,374 (1,524,783-3,048,077) |
*Excluding hip osteoarthritis, knee osteoarthritis, hand osteoarthritis, low back pain, neck pain and gout.
Here are a few observations that stand out:
- Ischemic heart disease is clearly the leading cause of DALYs, over 1.5 times as great as low back pain, the second leading cause of DALYs. Reducing the DALY impact of ischemic heart disease by 30% would be more effective than curing falls, major depressive disorder or age-related and other hearing loss.
- Tobacco contributes to three of the top five conditions (ischemic heart disease, chronic obstructive pulmonary disease and tracheal, bronchus and lung cancer).
- Addressing excessive caloric intake may address some fraction of the individuals suffering with back pain and diabetes, but it is unlikely to address other high-DALY conditions.
- We could really use more interventions (or more effective delivery of current interventions) to address the opioid epidemic.
- Of the ten most common procedures performed in America, only three address a single condition on the top 10 causes of DALYs (angioplasty, stents, and heart bypass surgery for ischemic heart disease). These interventions may reduce DALYs among a subset of patients with ischemic heart disease. None of the other most common procedures (cataract removal, Caesarean section, joint replacement, circumcision, broken bone repair, hysterectomy and gallbladder removal) address any of the other nine DALY leaders.
- Reducing our society’s stigma around hearing aids could dramatically reduce DALYs in this country.
The American Heart Association has been promoting its “Life’s Simple 7”. The seven issues to address cardiovascular health are: manage blood pressure, control cholesterol, reduce blood sugar, get active, eat better (clinical trial do data show meaningful reductions in cardiac risk), lose weight and stop smoking. Physicians struggle to consistently advise patients to get active, eat better, lose weight and stop smoking. In addition, physicians do not seem to reliably titrate medications to goal for blood pressure, cholesterol or blood sugar.
Primary prevention approach example – fixed-dose combination therapy to address cardiovascular risk factors
The Cochrane group’s 2017 meta-analysis reviewed the literature for fixed-dose combination therapy (typically aspirin, one or more antihypertensives and a statin) for the prevention of atherosclerotic cardiovascular diseases. The authors acknowledge that conventional approaches that target high-risk individuals, prescribing various medications, regular monitoring and dose titration are difficult to implement. Fixed-dose combination therapy would be expected to improve adherence to multidrug therapy. Thirty-six reports of 13 trials were included in the meta-analysis. The meta-analysis found no difference in all-cause mortality or cardiovascular events with different formulations of a “polypill.” Of the six analyses limited to atherosclerotic cardiovascular events, there was no clear signal that fixed-dose multi-drug regimens reduced those events. The authors admit that most included studies were designed to detect changes in risk factors (blood pressure, lipids) and higher-quality studies with longer follow-up periods will be needed to definitively determine if a fixed-dose combination therapy.
Secondary prevention approach example – cardiac rehabilitation
In 2016, Anderson et al. published a meta-analysis reviewing the effect of exercise-based cardiac rehabilitation for coronary heart disease. The group included 63 studies mentioned in 102 publications. The researchers found no reduction in total mortality, but they did not a 26% relative risk reduction in cardiovascular mortality with exercise-based cardiac rehabilitation. There was a reduction in hospital admissions, but no difference in coronary artery bypass grafts or percutaneous coronary interventions. The studies were too heterogeneous to consider health-related quality of life. The authors acknowledge the reality that advances in cardiovascular pharmaceutical interventions may have reduced the relative efficacy of exercise-based cardiac rehabilitation versus usual care. A 2016 Cochrane meta-analysis for exercise-based cardiac rehabilitation for coronary heart disease also published found similar results (i.e., lower cardiovascular mortality with no effect on total mortality, fewer hospitalizations but no reduction in risk for cardiovascular events or revascularization, improved health-related quality-of-life).
Conclusion
I started this post describing the USPSTF’s recent decision to broaden colon cancer screening to individuals 45-49 years of age. Although this change will reduce DALYs lost to colon cancer, there may be more effective ways to the overall American DALY burden. Cardiovascular disease has a disproportionate share of DALYs, so considering interventions among these patients might be worth pursuing. In addition to the two interventions I outlined, other interventions (e.g., secondary prevention: aspirin, statins, colchicine; patients with a low ejection fraction: beta-blockers, angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, mineralocorticoid receptor antagonists, angiotensin receptor-neprilysin inhibitors, implantable cardioverter-defibrillators; primary and secondary prevention: smoking cessation) may be worth investigating further. As we wait for our basic and clinical researchers to develop new innovations to manage ischemic heart disease, we as a clinical community could do more to make sure proven interventions are presented and prescribed to patients. If would prefer an “easier” way to reduce DALYs, perhaps we could encourage our technology colleagues to develop more hearing aids that are both effective and not socially stigmatizing, encouraging people to wear them.