Heart failure is a leading cause of hospitalization of the elderly. About 5 million Americans suffer from this disease, which has a high mortality rate. Control of blood pressure, use of ^-blockers, ACE inhibitors, and now spironolactone (Pitt et al 1999) will result in further improvement of mortality which have started to fall from 117 per 110000 in 1988 to 108 in 1995, according to the Center for Disease Control and Prevention (CDC).
Because of its severity, patients are on many concomitant medications apart from the aforementioned drugs, such as diuretics, digoxin, potassium supplements, medicines to improve pulmonary function, and antibiotics to control frequent infection in edematous and often emphysematous lungs. Measurements of heart function, and the long duration of these studies and large patient numbers required for mild to moderate heart failure (endpoint death), make these very challenging and expensive studies.
Hypertension affects about 50% of the elderly population. There is also a unique form called isolated systolic hypertension, which affects 9% of the geriatric population and is growing as the population ages. The challenges of doing studies in this area increase with the age of patients admitted, which correlates with increased concomitant medications and illness and compliance, but otherwise relates well to study designs in the younger age group.
Stroke thrombotic or hemorhagic is the third leading cause of death, killing 160 000 persons in the USA each year, Seven out of 10 victims are aged 65 or older. Of those that survive, one-third will be permanently disabled. Some improvements in these figures are hoped for, with earlier use of thrombolytics in case of cerebral thrombosis. As of 1999, over 20 new drugs were in development to treat this condition.
Arthritis causing inflammatory and degenerative changes around joints affects 43 million in the USA, and CDC projects that this will rise to 60 million by 2020. It can be caused by over 100 different diseases, but the commonest is osteoarth-ritis and rheumatoid arthritis. New medications, such as the antitumor necrotic factor a-blockers, raise fresh challenges to clinical study methodology because of limitations on non-clinical toxicity predictors and the application of biologic measurements on a traditional drug appraisal system.
The new non-steroidal anti-inflammatory drugs, including the Cox II inhibitors, because of the vast range of arthritic diseases, require that careful selection of indications for initial product approval must be undertaken. Rarely do companies have the time or money to develop all the pain indications (acute, chronic use) or to study arthritic diseases prior to product launch. As with hypertension, the numbers of patients required in the database will be large for product approval, especially for safety.
Depression is a frequently missed diagnosis in the elderly. The Alliance for Aging Research says that 15% of Americans aged 65 years and older experience clinically relevant depression. It can amplify the underlying disabilities in stroke, arthritis, Parkinson's disease, slow or prevent recovery from hip fracture and surgery, and be mimicked or masked by an underactive thyroid. The latest receptor-specific medicines have a very much reduced potential for adverse events and drug interactions. Difficulties can arise from confusion, memory impairment and disorientation, which are common in the depressed elderly. This brings challenges of ensuring both drug compliance and follow-up attendance in clinical studies. It also may require guardian co-signature for informed witnessed consent.
Parkinson's disease affects more than 1 million Americans and about four in every 100 by 75 years of age. Ten new drugs are under development. The patients may become very physically disabled but still retain a clear sensorium until the very end stages of the disease. Thus, drug compliance and follow-up visits are easier to achieve than with Alzheimer or depressed patients.
Alzheimer's disease is the eighth leading cause of death in the elderly and already affects some 4 million Americans. The incidence rises from 2% at 65 years to 32% at age 85. The National Institute of Health estimates that at least half of the people in nursing homes have this disease. A small study of donezil showed that this treatment avoided the need for home nursing care by half compared to those who did not receive the medicine (Small, 1998).
Clinical studies in this disease are very expensive, often requiring several collaborating disciplines at each investigative site. A gerontologist, a neurologist, a psychologist and a psychiatrist may be required, in addition to the usual support staff. Multiple cognitive tests and behavioral ratings of the patient often involving primary caregiver ratings, will be required—all this in addition to the basic Alzheimer's Disease Assessment Scale (ADAS-COG). These studies at present require large numbers of patients to show the often small improvement, as well as months of observation to detect a slowing of progression.
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