A person with comorbidity has two or more significant clinical conditions.
Most chronic diseases become more common with age. The likelihood of having two or more significant conditions is 60% by the age of 75-79 years, and more than 75% by 85-89 years. This is partly because of the way some diseases are defined; hypertension is a sustained blood pressure of over 140/90, and 75% of people over the age of 75 in UK have hypertension.
People with multiple morbidities are actively excluded from randomised trials because other diseases confuse and attenuate the trial outcomes. Observational studies show that patients with comorbidities do benefit from therapy but the more medications the patient takes, the more side effects occur and the worse compliance is. It can be difficult to determine whether a patient with multiple conditions gets a net benefit from treatment.
Primary prevention - control of a risk factor before it causes a disease - often requires you to treat many people to prevent one event. A decision should be made by balancing benefit with risk, and this is particularly important in older patients with comorbidities.
For instance, a 75-year-old man with atrial fibrillation has a 97% chance of not having a stroke in every year that he is not taking an anticoagulant. He can improve his chances of not having a stroke to 99% by taking an anticoagulant, although this might cause him to have a gastric bleed.
If the patient has advanced dementia and swallowing problems you may consider that the 2% gain in stroke prevention is not enough to outweigh the risk of death from aspiration pneumonia, for example. On the other hand, a stroke can be devastating.
Prescribing in older patients with comorbidities
In the absence of definite answers from clinical trials on older patients with comorbidities, prescribing can be complex. Taking medication is a choice and for the older patient with comorbidities there are few clear cut right or wrong decisions, but there are many options to consider.
Continue therapy if well tolerated
Prescribed medication can significantly benefit many patients and the default position should be to continue therapy if it is well tolerated and supported. However, some drugs are given to manage side effects caused by other drugs. For example, diuretics are given for ankle swelling caused by amlodipine. Consider whether you could discontinue both drugs. The Screening Tool of Older People’s potentially inappropriate Prescriptions (STOPP) criteria is useful.1
Review medication when appropriate
If the intended target of treatment is not being met, discuss this again with the patient. Check that they are taking the medicine correctly. Some 50% of older patients are not taking the desired dose of statin two years after a heart attack. Dementia or increased frailty or dependency should prompt a review of medication.
Treat distressing symptoms
Treating distressing symptoms is always the right thing to do. This is more important than treating things that haven't happened yet, if a choice has to be made.
Use sub-maximal doses
Feel free to use sub-maximal doses of medicine. It is unlikely the full dose of any drug you want to prescribe has been tested on a patient with the combination of diseases you are treating and adverse effects are more common in older patients.
Prioritise secondary prevention
Drugs are more effective, in absolute terms, for secondary rather than primary prevention of disease. If the patient has already had a stroke, their risk of another is as much as ten times higher than if they had not. Very few primary preventive drugs benefit more than one person in fifty each year.
Respect your patient’s decisions
Discuss likely risk with your patient, and ask if they want treatment. Some older people want treatment to be given to younger people who they believe have more to gain. Your patient’s relatives may have a different view. It is important to understand the reasoning behind the patient's informed decision. Remember that people are allowed to make different decisions to that which we would make ourselves. But usually older patients want to do what their clinician thinks is best.
Aim to ‘add life to years’
The motto of the British Geriatrics Society is 'adding life to years'. Remember this when managing your older patients with comorbidities. If your treatment causes more discomfort and trouble than the disease, then it is probably the wrong approach.
It is never too late for patients to make lifestyle changes, so do discuss this with older patients. Stopping smoking, walking more and eating more vegetables are all good ways for patients to take responsibility for their health.
While all patients are individuals (particularly those with multiple morbidities, who may all have different combinations of problems) it is important to remember that the final concerns and limitations for older people are often the same. Their horizons may be reduced by immobility so they become confined to the house or a room. They may feel frustration and disappointment at their loss of personal independence.
- Dr Richard Day, consultant geriatrician, Poole Hospital NHS Trust, Dorset
- Gallagher P, Ryan C, Byrne S et al. STOPP (Screening Tool of Older Person's Prescriptions) and START (Screening Tool to Alert doctors to Right Treatment). Consensus validation. Int J Clin Pharmacol Ther. 2008; 46(2): 72-83
Melzer D, Delgado JC, Winder R et al . The Age UK Almanac of Disease Profiles in later Life. NIHR, 2015.