Correlation between salivary alpha-amylase activity and pain scale in patients with chronic pain.
OBJECTIVE
The visual analog scale (VAS) is commonly used to assess pain intensity. However, the VAS is of limited value if patients fail to reliably report. Objective assessments are therefore clearly preferable. Previous reports suggest that elevated salivary alpha-amylase may reflect increased physical stress. There is a close association between salivary alpha-amylase and plasma norepinephrine under stressful physical conditions. In this study, we have determined the usefulness of a portable salivary alpha-amylase analyzer as an objective biomarker of stress.


METHODS
Thirty patients (male/female = 15/15, age: 60.5 +/- 15.3 years) with chronic low back or leg pain (pain (+) group) and 20 pain-free control patients undergoing elective surgery under general anesthesia with epidural analgesia (pain (-) group) were recruited. Patients received epidural block with 5 to 10 mL 1% lidocaine. VAS, blood pressure, and heart rates were assessed before and 30 and 45 minutes after the epidural block. Salivary alpha-amylase was simultaneously measured using a portable analyzer. The relationship between the VAS and salivary alpha-amylase in chronic pain patients was assessed.


RESULTS
After the epidural block both heart rate and systolic blood pressure decreased by approximately 8%. In the pain (+) group, the epidural block markedly decreased the VAS pain scale and salivary alpha-amylase from 56 +/- 22 to 19 +/- 16 mm (P < .01) and from 82 +/- 48 to 45 +/- 28 U/mL (P < .01), respectively, with a significant correlation between the 2 measures (r = 0.561, P < .01). In contrast, salivary alpha-amylase did not change significantly in the pain (-) group.


CONCLUSIONS
Because there was a significant correlation between VAS pain scale and salivary alpha-amylase, we suggest that this biomarker may be a good index for the objective assessment of pain intensity. In addition, a simple to use portable analyzer may be useful for such assessment.
Shirasaki
Shyuichi
S
Department of Anesthesiology, Caress Alliance Tenshi Hospital, Sapporo, Japan.
Fujii
Hitomi
H
Takahashi
Miho
M
Sato
Tetsumi
T
Ebina
Masako
M
Noto
Yuka
Y
Hirota
Kazuyoshi
K
D000368:Aged; D015360:Analgesia, Epidural; D000704:Analysis of Variance; D000779:Anesthetics, Local; D015415:Biomarkers / Q000378:metabolism; D001794:Blood Pressure / Q000502:physiology; D002908:Chronic Disease; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007866:Leg; D008012:Lidocaine; D017116:Low Back Pain / Q000201:enzymology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000201:enzymology / Q000503:physiopathology*; D010147:Pain Measurement; D012463:Saliva / Q000201:enzymology*; D013312:Stress, Physiological / Q000201:enzymology; D013997:Time Factors; D000516:alpha-Amylases / Q000378:metabolism*
D000779:Anesthetics, Local; D015415:Biomarkers; D008012:Lidocaine; D000516:alpha-Amylases