Guidelines for determining prognosis: amyotrophic lateral sclerosis (ALS)
Amyotrophic lateral sclerosis (ALS) is a progressive neurologic disease that is fatal in about three fourths of patients within one to five years after symptom onset, with median survival of 4 years or less, although some studies indicate longer survival in some patients with symptom onset before age 45. The cause is unknown in 90% of cases, and at present there is no effective treatment. Crude mortality rates from ALS have risen about 50% in the last fifteen years, but this appears due to declining competitive mortality from ischemic heart disease and stroke rather than rising incidence of ALS.
Although the disease usually starts with focal involvement, patients become quadriplegic and unable to speak, swallow and ultimately to breathe. A small percentage of patients may survive beyond five years, particularly with ventilators and feeding tubes, although centers specializing in the care of patients with advanced ALS report that with counseling, very few of them choose assisted ventilation.
For predicting prognosis in ALS, several characteristics of the disease are important to remember:
• ALS tends to progress in a linear fashion over time. Thus the overall rate of decline in each patient is fairly constant and predictable, unlike many other non-cancer diseases.
• However, no single variable deteriorates at a uniform rate in all patients. Therefore, multiple clinical parameters are required to judge the progression of ALS.
• Although ALS usually presents in a localized anatomical area, the location of initial presentation does not correlate with survival time. By the time patients become end-stage, muscle denervation has become widespread, affecting all areas of the body, and initial predominance patterns do not persist. Bulbar presentation, for example, was thought to correlate with relatively poor prognosis, but more recent studies have shown that bulbar cases present with later age of onset, which does correlate with more rapid progression.
• Progression of disease differs markedly from patient to patient, as much as 60-fold in one series. Some patients decline rapidly and die quickly; others progress more slowly. For this reason, the history of the rate of progression in individual patients is important to obtain to predict prognosis.
• In end-stage ALS, two factors are critical in determining prognosis: ability to breathe, and to a lesser extent ability to swallow. The former can be managed by artificial ventilation, and the latter by gastrostomy or other artificial feeding, unless the patient has recurrent aspiration pneumonia.
Numerous ALS rating scales have been developed to help predict ALS prognosis for use in drug intervention trials. Although the predictive value of some are excellent, they are meant to grade patients in all stages of the disease. Their clinical complexity precludes their use by most hospice staffs, and many medical directors, without special training. More importantly, the only factor that is critical in end-stage ALS is respiratory function. The other variables considered in these rating systems, e.g. muscle strength, bulbar function other than swallowing, and upper and lower extremity function, are irrelevant in predicting six-month prognosis.
Examination by a neurologist within three months of assessment for hospice is advised, both to confirm the diagnosis and to assist with prognosis.
The following factors may define those ALS patients with expected survival of approximately six months.
These patients generally fit one of the following categories
1. Both rapid progression of ALS and critically impaired ventilatory capacity.
2. Both rapid progression of ALS and critical nutritional impairment, with a decision not to receive artificial feeding.
3. Both rapid progression of ALS and life-threatening complications.
I. Rapid progression of disease and critically impaired ventilatory capacity.
A. Rapid progression of ALS.
The patient should have developed most of their disability within the past 12 months. Patients with slow progression may survive for longer periods, although clinical judgment may still indicate they may be within six months of death.
Examples would include, within the past year:
A1. Progressing from independent ambulation to wheelchair- or bed-bound.
A2. Progressing from normal to barely intelligible or unintelligible speech.
A3. Progressing from normal to blenderized diet.
A4. Progressing from independence in most or all Activities of Daily Living (ADL's) to needing major assist by caretaker in all ADL's.
B. Critically impaired ventilatory capacity.
The patient should have, within the past 12 months, developed extremely severe breathing disability. Examples include:
B1. Vital Capacity (VC) less than 30% of predicted.
B2. Significant dyspnea at rest.
B3. Requiring supplemental oxygen at rest.
B4. Patient declines intubation or tracheotomy and mechanical ventilation.
Note: Patients who are already on assisted ventilation, whether by negative-pressure external means (e.g. Cuirass) or positive-pressure through tracheotomy, may survive for periods considerably longer than six months unless there is a life-threatening comorbid condition, e.g. recurrent aspiration pneumonia.
II. Rapid progression of ALS and critical nutritional impairment.
A. Rapid progression of ALS. Please see I.A. above.
B. Critical nutritional impairment.
Most ALS patients develop swallowing difficulties early in the illness, so that gastrostomy feeding is reasonable.
However, some patients with end-stage or rapidly-advancing ALS may choose not to undergo artificial feeding.
These patients may have a prognosis of less than six months if their oral intake of nutrients and fluids is insufficient to sustain life.
Nutritional impairment may be documented by (1) continued weight loss and (2) dehydration or hypovolemia.
III. Rapid progression of ALS and life-threatening complications.
A. Rapid progression of ALS. Please see I.A. above.
B. Life-threatening complications.
B1. Recurrent aspiration pneumonia. This may occur whether or not the patient is receiving tube feedings.
B2. Decubitus ulcers, multiple, Stage 3-4, particularly if infected.
B3. Upper urinary tract infection, e.g. pyelonephritis.
B5. Fever recurrent after antibiotics.
Published by The National Hospice Organization, 1996.
See also: Progressive neurologic disorders
Reference: U.S. Department of Health and Human Services. Assistant Secretary for Planning and Evaluation. Internet. Accessed April 29, 2010. Available at http://aspe.hhs.gov/daltcp/Reports/impquesa.htm#appendixC.