Beta 2-microglobulin predicts survival in primary systemic amyloidosis.
OBJECTIVE
The study assessed whether beta 2-microglobulin levels predict survival or response in patients with primary systemic amyloidosis without associated multiple myeloma.


METHODS
The study group consisted of 131 untreated patients with biopsy-proven primary systemic amyloidosis diagnosed and evaluated at the Mayo Clinic. No patient had multiple myeloma. The minimum follow-up of surviving patients is 8 years. No patient was lost to follow-up.


RESULTS
The median survival of patients with an increased beta 2-microglobulin level was 10.8 months, compared with patients with a normal beta 2-microglobulin level (less than or equal to 2.7 micrograms/mL, 0.23 mumol/L) of 32.9 months (p less than 0.001). In a multivariate proportional-hazards model, the best model included congestive heart failure (p less than 0.0001) and increased beta 2-microglobulin levels (p less than 0.05). After adjustment for the presence of congestive heart failure, beta 2-microglobulin level remained significant. When the analysis was restricted to those patients with normal renal function, the median survival of those with an elevated beta 2-microglobulin level was 9.1 months versus 39.4 months for those with a normal level (p less than 0.001). The serum level of beta 2-microglobulin was increased in patients with nephrotic-range proteinuria with or without renal insufficiency (p = 0.05).


CONCLUSIONS
The serum beta 2-microglobulin level should be measured routinely in all patients with primary systemic amyloidosis because it provides a useful objective factor to identify subsets of patients with this disease who have unfavorable outcomes.
Gertz
M A
MA
Dysproteinemia Clinic, Mayo Clinic, Rochester, Minnesota 55905.
Kyle
R A
RA
Greipp
P R
PR
Katzmann
J A
JA
O'Fallon
W M
WM
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000686:Amyloidosis / Q000097:blood / Q000188:drug therapy / Q000401:mortality*; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood / Q000652:urine; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000150:complications; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011336:Probability; D016016:Proportional Hazards Models; D011507:Proteinuria / Q000097:blood; D016019:Survival Analysis; D001613:beta 2-Microglobulin / Q000032:analysis*
D001613:beta 2-Microglobulin; D003404:Creatinine