On the threshold - evaluation of variability in effects of acupuncture in a gender perspective.
Variable results of pain alleviation in response to acupuncture have been reported, complicating its interpretation. Sources of variability are probably multi-factorial, including the contribution of gender related effects. Gender related variation in perceived pain has been discussed frequently, but documented effects of acupuncture referring to gender are sparse. Furthermore, factors such as operationalisation of the outcome variable and the statistical method for evaluation could also be sources of variability. When pain is regarded as subjective, the produced data should be treated as ordinal. The rank-based method by Svensson, taking the non-metric qualities of the ordinal data into account as well as the variability at the group and the individual level, is therefore an alternative. The present commentary aims to (1) evaluate changes in electrical sensory thresholds and electrical pain thresholds after low frequency electro-acupuncture separately in healthy women and men; (2) introduce and exemplify the method by Svensson in a user-friendly approach. To analyze the systematic patterns of change in thresholds, indicating evidence of treatment on a group level, the relative position (RP) and relative concentration (RC), were measured. The variation related to the individual, the relative rank variation (RV) was also measured. The results were divergent between women (n = 23) and men (n = 22), i.e. unchanged sensory threshold after acupuncture at the group level in women while changed in men. The assessed pain threshold after acupuncture on the other hand was changed towards higher levels in women and unchanged in men. The individual variation was apparent in both women and men but larger in women. For statistical analysis of the variability for both group and individual related effects, the rank-based method by Svensson could be used. The present study indicates that evaluation of sensory and pain threshold response should be analysed separately in women and men.
Lund
Iréne
I
Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden. Irene.Lund@ki.se.
Lundeberg
Thomas
T
J Postgrad Med. 2008 Jul-Sep;54(3):214-6
18626172
Stat Med. 1998 Dec 30;17(24):2923-36
9921610
Horm Behav. 2006 Jun;50(1):1-7
16423353
BMJ. 2004 Nov 20;329(7476):1216
15494348
BMC Complement Altern Med. 2006 May 23;6:20
16719906
Prog Neuropsychopharmacol Biol Psychiatry. 2000 Apr;24(3):385-95
10836487
Rheumatology (Oxford). 2008 Jun;47(6):887-93
18403402
Ann Neurol. 2008 Apr;63(4):507-12
18300313
Arch Phys Med Rehabil. 1989 Apr;70(4):308-12
2535599
Health Phys. 2007 Jun;92(6):591-5
17495660
Ann Intern Med. 2007 Jun 19;146(12):868-77
17577006
Acupunct Med. 2007 Jun;25(1-2):29-35
17641565
BMJ. 2005 Aug 13;331(7513):376-82
16055451
Med Hypotheses. 1995 Sep;45(3):271-81
8569551
Pain. 2007 Nov;132 Suppl 1:S1-S2
17951005
Lancet. 2005 Jul 9-15;366(9480):136-43
16005336
Acupunct Med. 2008 Jun;26(2):111-20
18591910
J Rehabil Med. 2001 Nov;33(6):279-83
11766958
Pain. 2006 May;122(1-2):81-9
16527396
Curr Rheumatol Rep. 2007 Dec;9(6):473-81
18177601
J Rehabil Med. 2002 Nov;34(6):251-9
12440798
Nat Neurosci. 2002 Nov;5 Suppl:1062-7
12403987
Acupunct Med. 2006 Sep;24(3):109-17
17013357
J Clin Epidemiol. 2007 Mar;60(3):280-7
17292022
Acupunct Med. 2008 Mar;26(1):33-45
18356797
Arch Intern Med. 2006 Feb 27;166(4):450-7
16505266
Physiother Theory Pract. 2005 Apr-Jun;21(2):81-92
16392461
J Rehabil Med. 2001 Jan;33(1):47-8
11480471
Headache. 2006 Nov-Dec;46(10):1492-502
17115982
BMC Complement Altern Med. 2008 May 01;8:18
18452622
Man Ther. 2009 Feb;14(1):3-12
18511329
Rheumatology (Oxford). 2007 Mar;46(3):384-90
17215263
Neurosci Lett. 2005 Feb 28;375(2):75-80
15670645