Lifetime risk and multimorbidity of non-communicable diseases and disease-free life expectancy in the general population: A population-based cohort study

Abstract

Background: Non-communicable diseases (NCDs) are leading causes of premature disability and death worldwide. However, the lifetime risk of developing any NCD is unknown, as are the effects of shared common risk factors on this risk.

Methods and findings: Between July 6, 1989, and January 1, 2012, we followed participants from the prospective Rotterdam Study aged 45 years and older who were free from NCDs at baseline for incident stroke, heart disease, diabetes, chronic respiratory disease, cancer, and neurodegenerative disease. We quantified occurrence/co-occurrence and remaining lifetime risk of any NCD in a competing risk framework. We additionally studied the lifetime risk of any NCD, age at onset, and overall life expectancy for strata of 3 shared risk factors at baseline: smoking, hypertension, and overweight. During 75,354 person-years of follow-up from a total of 9,061 participants (mean age 63.9 years, 60.1% women), 814 participants were diagnosed with stroke, 1,571 with heart disease, 625 with diabetes, 1,004 with chronic respiratory disease, 1,538 with cancer, and 1,065 with neurodegenerative disease. NCDs tended to co-occur substantially, with 1,563 participants (33.7% of those who developed any NCD) diagnosed with multiple diseases during follow-up. The lifetime risk of any NCD from the age of 45 years onwards was 94.0% (95% CI 92.9%-95.1%) for men and 92.8% (95% CI 91.8%-93.8%) for women. These risks remained high (>90.0%) even for those without the 3 risk factors of smoking, hypertension, and overweight. Absence of smoking, hypertension, and overweight was associated with a 9.0-year delay (95% CI 6.3-11.6) in the age at onset of any NCD. Furthermore, the overall life expectancy for participants without these risk factors was 6.0 years (95% CI 5.2-6.8) longer than for those with all 3 risk factors. Participants aged 45 years and older without the 3 risk factors of smoking, hypertension, and overweight at baseline spent 21.6% of their remaining lifetime with 1 or more NCDs, compared to 31.8% of their remaining life for participants with all of these risk factors at baseline. This difference corresponds to a 2-year compression of morbidity of NCDs. Limitations of this study include potential residual confounding, unmeasured changes in risk factor profiles during follow-up, and potentially limited generalisability to different healthcare settings and populations not of European descent.

Conclusions: Our study suggests that in this western European community, 9 out of 10 individuals aged 45 years and older develop an NCD during their remaining lifetime. Among those individuals who develop an NCD, at least a third are subsequently diagnosed with multiple NCDs. Absence of 3 common shared risk factors is associated with compression of morbidity of NCDs. These findings underscore the importance of avoidance of these common shared risk factors to reduce the premature morbidity and mortality attributable to NCDs.

Fig 1. Intersection diagram depicting patterns of occurrence/co-occurrence of NCDs quantified as the number of events.

Of all participants who developed an NCD during follow-up, a third (33.7%) were diagnosed with more than 1 of these diseases, including 1 individual who was diagnosed with all 6 diseases. The left panel displays bars for each disease separately that quantify the solitary number of events per disease, highlighting, for instance, that stroke occurred more frequently during follow-up than diabetes (814 versus 625 events, respectively). Yet stoke also showed more overlap with other NCDs compared to diabetes (254 solitary stroke events versus 294 solitary diabetes events). Events from participants who had at least 1 of the common shared risk factors (current smoking, hypertension, or overweight) at baseline are shown in red. NCD, non-communicable disease.

Fig 2. Lifetime risk of NCDs for 45-year-old men and women.

In this analysis, follow-up ended at the time of first occurrence of an NCD. For instance, for participants who first experienced heart disease and subsequently developed neurodegenerative disease, only heart disease is considered here. NCD, non-communicable disease.

Fig 3. Lifetime risk of NCD stratified by risk factor burden.

In this analysis, follow-up ended at the time of first occurrence of an NCD. For instance, for participants who first experienced heart disease and subsequently developed neurodegenerative disease, only heart disease is considered here. NCD, non-communicable disease.

Fig 4. Cumulative incidence of NCD by risk factor burden.

On average, a 9-year difference was observed in age at NCD onset between participants with all 3 risk factors (red) and those with no risk factors (green) at baseline. For example, at age 55 years, cumulative incidence was 14.3% for those with all 3 risk factors, whereas this cumulative incidence was not reached until age 62.5 years (i.e., 7.5 years later) for those without the risk factors. Similarly, at age 75 years, cumulative incidence was 73.2% for those with all 3 risk factors, whereas this cumulative incidence was not reached until age 86 years (i.e., 11 years later) for those without the risk factors. NCD, non-communicable disease.

Fig 5. Remaining life expectancy at age 45 years with and without NCD stratified by risk factor burden.

Participants aged 45 years and older without the 3 risk factors of smoking, hypertension, and overweight at baseline spent 21.6% (8.3 years divided by 38.4 years) of their remaining lifetime with at least 1 NCD, which was a substantially lower proportion compared to the 31.8% (10.3 years divided by 32.4 years) for those with all 3 of these risk factors at baseline. Error bars represent 95% confidence intervals. NCD, non-communicable disease.