Signs of bodily "wear and tear" in midlife went with a higher risk of frailty years later

Frailty is not simply being old. It is a state in which the body has little reserve left: people are weak, slow, tired, and lose weight without trying, and small illnesses can knock them over. It can be prevented and sometimes reversed, so spotting who is heading towards it, years before it shows, would be useful. A study from the UK suggests that a simple count of "strained" body systems in people aged 50 and over may help. People with the highest scores were more likely to become frail over the next 12 years. The study shows a link, not a cause.

The score measures what researchers call allostatic load: the wear and tear that builds up when the body has to keep adjusting to long-lasting stress. It is usually estimated from routine measurements such as blood pressure, cholesterol and markers of inflammation. Unlike frailty, it can be measured at any age. Earlier studies had linked the two, but many included people who were already frail, so it was unclear which came first.

What they did

The team used the English Longitudinal Study of Ageing (ELSA), which regularly interviews and examines a large sample of people aged 50 and over living in England. They planned the analysis in advance and had the plan peer-reviewed before looking at the data (a format called a Registered Report).

They selected 3,248 people aged 50 to 89 who, in 2004/2005, showed none of the five standard signs of frailty: slow walking, weak grip, exhaustion, very little physical activity, and unintended weight loss. Having one or two of these signs counts as pre-frailty, three or more as frailty.

From that first visit, the team built an allostatic load score from seven measurements in four body systems:

• immune: C-reactive protein and fibrinogen, two blood markers of inflammation;
• metabolic: the ratio of total to "good" HDL cholesterol, and blood fats called triglycerides;
• cardiovascular: upper and lower blood pressure;
• body fat: body mass index.

Each system scored 1 if it showed high-risk values, giving a total from 0 to 4. Frailty was then checked about every four years over the following 12 years. The analysis took into account age, sex, retirement, education, wealth, smoking, drinking, body mass index, memory and thinking scores, and how socially connected and supported people were.

What they found

• Who became frail. Over 12 years, 186 people (6%) became frail and 1,215 (37%) became pre-frail.
• Higher score, higher risk. Before other factors were considered, each step up in the score went with a greater chance of both frailty and pre-frailty. After everything was accounted for, the link remained only at the top: a score of 4 (strain in all four systems) predicted frailty, and a score of 3 predicted pre-frailty. The exact odds are in the paper's tables.
• Not just the oldest. The link was seen in a sample that was fairly young on average (63 years), and it did not differ significantly by age or sex.
• Social support. People with low or medium social support were more likely to become frail, with about 1.5 to 1.7 times the odds of those with the most support. Older age and a higher body mass index also raised the odds; more wealth and better thinking scores lowered them.

What to keep in mind

The authors are open about the weaknesses:

• Many people were lost. Missing data were common: 60% of the sample was lost for the frailty analysis and 46% for pre-frailty. Those who dropped out of the frailty analysis were older, poorer, less educated and more often smokers. The remaining group was mostly under 70, fairly well educated and better off, so the results apply mainly to such people. Ethnicity was not considered.
• Healthy at the start. Only people with no frailty signs at all were included, so the findings say little about people who are already pre-frail.
• A simplified score. A long-term blood sugar measure had to be dropped because too much of it was missing, and the cut-offs for "high risk" came from the sample itself, which makes comparison with other studies harder. Several parts of the pre-registered plan had to be changed once the data were seen, and the planned analysis by age group was not possible because there were too few frailty cases.
• Associations only. The link weakened once other factors were included, which suggests that stress load, money, social life and health overlap. The study cannot say that lowering the score would prevent frailty.

Why it matters

Frailty is usually noticed only when it is already there. This study suggests that measurements many people get at a routine check-up, combined into one score, could flag a higher risk more than a decade earlier, even in people in their fifties and sixties. The authors propose the score as a possible screening tool and point to social support as something that can be changed, but both ideas still need to be tested in studies that try to intervene.