ORIGINAL ARTICLE

Applicability of Press Needles to a Double-blind Trial
A Randomized, Double-blind, Placebo-controlled Trial
Shougo Miyazaki, DPE,* Akihito Hagihara, DMSc, MPH,* Ryo Kanda, DPE,w
Yoshito Mukaino, MD, PhD,w and Koichi Nobutomo, MD, PhD*

Objectives: Owing to a lack of a suitable needle procedure, it has
been impossible to evaluate the eﬃcacy of acupuncture in clinicalstudies using double-blind testing. We evaluated the applicability ofa new kind of press needle (Pyonex) to a double-blind trial bycomparing the press needle with a placebo (lacking the needle
element).
Methods: The purpose of the study consisted of 2 phases. In thephase 1, to evaluate the applicability and eﬃcacy of the press
needles, 90 participants who had never been treated using
acupuncture were randomly assigned to receive either the press
needle (n = 45) or a placebo (n = 45). The applicability wasmeasured using a questionnaire regarding the perception ofpenetration, and eﬃcacy was measured using a visual analog scaleof low back pain (LBP). When the applicability and eﬃcacy of thepress needles were conﬁrmed in phase 1, the mechanism of LBP
relief by the press needles was examined in phase 2.
Results: In phase 1, intergroup comparisons showed no signiﬁcantdiﬀerences concerning the perception of penetration. In addition,
for patients with LBP, the press needles reduced the subjective
evaluation of LBP compared with the placebo (P<0.05). In phase2, visual analog scale results indicated that LBP was reduced
signiﬁcantly more in the press needle group than in the local
anesthesia group (P<0.05).
Discussion: The participants could not distinguish between thepress needle and a placebo, and the data from the press needle
group suggested a speciﬁc inﬂuence on patients with LBP. Theseﬁndings imply that the press needle and a placebo provide aneﬀective means of realizing a double-blind setting for clinicalstudies of acupuncture.

Received for publication July 22, 2008; revised October 7, 2008;
accepted October 28, 2008.
From the *Department of Health Services, Management and Policy,
Graduate School of Medical Sciences, Kyushu University; andwFaculty of Sports and Health Science, Fukuoka University,
Fukuoka, Japan.
Contributors: All authors participated in developing the study design
and protocol and in revising the manuscript. Speciﬁc tasks andresponsibilities were general trial coordination (S.M., R.K., Y.M.),
monitoring coordination (S.M., R.K.), statistical analysis andexpertise (A.H.), acupuncture interventions (S.M.), general medical
and scientiﬁc responsibility (Y.M., K.N.), and the randomization(Seirin Corporation).
The authors declare that there is no conﬂict of interest.
Seirin Corporation participated in random allocation and supplied thepress needles (Pyonex) and placebo devices. Maruho Corporation
and Nittou Dennkou Corporation (Osaka, Japan) supplied thelidocaine patches (Penles). However, this study was not funded byany corporations or organizations.
All authors had full access to the study data on request. The corresponding author had full access to all data and ﬁnal responsibility
for submitting the article for publication.
Reprints: Prof Akihito Hagihara, DMSc, MPH, Department of HealthServices, Management and Policy, Graduate School of Medical
Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka
812-8582, Japan (e-mail: hagihara@hsmp.med.kyushu-u.ac.jp).
Copyright r 2009 by Lippincott Williams & Wilkins

438 | www.clinicalpain.com

Key Words: placebo, press needle, double-blind method, low backpain, randomized controlled trial(Clin J Pain 2009;25:438–444)

S

ince the 1990s, several studies have evaluated the speciﬁc
eﬀects of acupuncture, that is, the eﬀects of the insertionof a needle at an appropriate acupoint.1–6 However, thesestudies are insuﬃcient because of 3 main problems. First,
although ‘‘sham’’ or placebo needles can be used as acontrol treatment7,8 for a single-blind testing method (bymasking the treatment allocation from the study participants), masking the treatment from practitioners, which is
required for a double-blind testing method, is not possible.
Second, the sham needling applied as a placebo needle
in previous studies has been referred to as ‘‘shallow needling’’ (depth of insertion <2 mm) or ‘‘contact needling’’ (amethod of obtaining therapeutic eﬀects by holding theneedlepoint on the skin surface without penetrating theskin).9 However, shallow needling has speciﬁc physiologic
eﬀects,10 and whereas not as eﬀective as actual acupuncture, it has been proven eﬀective compared with a notreatment control group.3,11 Thus, studies using shallow
needling as placebo needles for the control group probably
produce a skewed interpretation of the speciﬁc or placebo
eﬀect of acupuncture. Third, the risk for adverse events isvery low when acupuncture is applied by qualiﬁed
professionals,12–16 and the majority of the adverse events
identiﬁed from acupuncture clinical trials were of low risk,
not mild risk.2,17–19 However, no study has reported
adverse events as a problem in the design and developmentof acupuncture trials. In addition, interventions using a realneedle (lengths from 20 to 40 mm) are painful. A survey ofhealthcare consumers’ perceptions of acupuncture in Japan
found that the most frequent response was that it was‘‘painful.’’20 Thus, individuals may avoid treatment due tofear of pain. In pursuit of safe acupuncture, Yamashita
et al21 argued that the less-invasive shallow needling andcontact needling should not be considered sham or placebo
acupuncture but should be acknowledged as safer methodsof acupuncture in Japan and worldwide.
The press needles, which are used for a type of shallow
needling22, may allow treatment allocation to be masked
from practitioners and study participants; these needles
cause almost no sensation at the time of insertion and canbe removed from the insertion device without obvious
diﬀerences. Therefore, the use of press needles may enable
double-blind testing for eﬀects speciﬁcally associatedwith metal (acupuncture) penetration of the skin at an
acupoint site.
Clin J Pain  Volume 25, Number 5, June 2009

Clin J Pain  Volume 25, Number 5, June 2009

Applicability of Press Needles to a Double-blind Trial

The lack of a suitable placebo needle procedure has
prevented double-blind studies from evaluating the eﬃcacy
of acupuncture. To evaluate the eﬃcacy, applicability, andsafety of press needles, we compared the press needle with aplacebo, which was the same device only lacking the needle
element. Our ﬁndings should be useful in planning doubleblind testing of acupuncture.

METHODS
Study Participants
We recruited study participants from among the 811
male undergraduate students who were registered in May
2007 at the Faculty of Sports and Health Sciences,
Fukuoka University, Japan. We randomly selected 252
students, aged 20 years or above, and contacted them to ask
whether they had ever received acupuncture treatment. At alater date, we provided the 118 students (46.8%) who had
not received acupuncture treatment with a written explanation of the study; 90 students (76.3%) agreed to participate.
Of the 90 participants, we excluded 9 individuals forphysical reasons (n = 4) or noncompliance (n = 5) during
the study. Physical reasons encompassed the cases thatreceived medical care for disease or injury. The study
protocols were approved by the ethics committee at
Fukuoka University, and all interventions were conducted
there.

Baseline Characteristics
All participants were validated as follows, for allocation: age, height, weight, body mass index, sitting height,
and sit-and-reach distance. Additionally, all participants
were questioned about the extent of low back pain (LBP) toestablish a baseline (or for allocation): (1) presence orabsence of LBP during the past several days (for allocation); (2) visual analog scale (VAS) rating of LBP; (3)duration of LBP based on 10 response categories (0: nopain, 1: <1 wk, 2: Z1 wk and <1 mo, 3: Z1 mo and<3 mo, 4: Z3 mo and <6 mo, 5: Z6 mo and <1 y, 6:
Z1 y and <5 y, 7: Z5 y and <10 y, 8: Z10 y and <20 y,
9: Z20 y); (4) days per month with LBP based on 5
response categories (0: no pain, 1: 1 to 3 d, 2: 4 to 6 d, 3: 7 to
14 d, 4Z15 d); and (5) the Roland-Morris Disability
Questionnaire,23 range: 0 to 24.

ProceduresIntervention and Placebo
Figure 1 shows the structure and operation of the press
needles used in this study (Pyonex; Seirin Corporation,
Shizuoka, Japan); each needle had a diameter of 0.2 mm
and length of 0.6 mm. The placebo was identical to thepress needle, except the needle element had been removed.
The press needles and placebos were packed individually in
identical pouches, each of which was assigned a consecutive
number. The treatment allocation was not disclosed to
study participants, the practitioner, or the evaluator during
the period of study.
The press needles and placebo devices were administered (inserted) following the same procedures, according to
the product directions, by a single acupuncturist with 10
years of clinical experience. To ensure that the treatment
method was masked to the practitioner, the acupuncturist
was asked not to check for the presence of a needle during
r 2009 Lippincott Williams & Wilkins

FIGURE 1. Structure and operation of the press needle (Pyonex).
The top figure shows the following components: ( ) needle(stainless steel), ( ) tape, ( ) resin, ( ) sheath (lunate sheet),and ( ) cartridge (plastic case). The figure in the lower left( ) shows the process of taking the Pyonex needle out of the
cartridge ( ) by picking up the sheath ( ) with tape ( ).
The figure in the lower right ( ) shows the process of applying
the Pyonex needle to an acupoint. It is placed on an acupointwith the sheath ( ) attached, pressed down lightly on the top,
and inserted. Then, the sheath ( ) is stood at a right angle to theskin. Finally, as shown in the figure, the tape ( ) is removed.

the process of insertion. A diﬀerent researcher recorded themeasurements, and a physician controlled the safety ofneedle insertion and conﬁrmed that the treatment method
was masked.

Study Design
The study consisted of 2 phases. Phase 1 was a doubleblind, randomized, placebo-controlled experiment to test
the applicability, eﬃcacy, and safety of the press needles.
Phase 2 was designed to study the mechanism by which
the press needles relieved LBP. Study participants wererecruited from September 18 to October 31, 2007.
A washout period of at least 4 weeks took place between
phases 1 and 2.

Endpoints
The primary endpoint was the applicability as
measured by responses to a questionnaire-based assessment
for conﬁrming the applicability of the press needles to blind
testing. Participants were asked 3 questions regarding theperception of penetration, the perception of de qi (dullsensation), and whether they thought they had received real
acupuncture. Participants could choose from 3 responses:
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Clin J Pain  Volume 25, Number 5, June 2009

Miyazaki et al‘‘felt a sensation’’ (yes), ‘‘did not feel a sensation’’ (no), or‘‘could not discriminate.’’ For the same purpose, pain was
evaluated using the short form of the McGill Pain
Questionnaire.24,25
In addition to applicability, we conﬁrmed the eﬃcacy
and safety of the press needles. Eﬃcacy was measured using
a VAS of LBP, with the scale ranging from 0 (no pain) to100 (most intense pain). Measurements were performed atbaseline, immediately after administration, and 20 min afteradministration. Diﬀerences from baseline were analyzed.
We used previous ﬁndings26 to assess 10 types of possible
adverse eﬀects of acupuncture on a 4-point scale of safety
from 0 (no risk) to 3 (strong risk).

Acupoint (BL23)
We selected the acupoint at the left side of the BL23.
This site is typically used in acupuncture treatment for
LBP,27 and we decided it was the most appropriate site
based on factors that might have aﬀected the applicabilityof the placebo (eg, visual eﬀect).28 For the same reason,study participants were limited to individuals who had notreceived acupuncture.

Local Anesthesia Before NeedlingPhase 2 of this study was designed to clarify themechanism for the analgesic eﬀect of the press needles on
LBP. Before the insertion of the press needle, a topicalanesthetic patch (lidocaine patch; Penles) was applied for
30 min to block the peripheral nerve ﬁbers around theacupoint site. Subsequent analysis compared a group who
were treated with the press needles after local anesthesia(LA) and a group who were treated with the press needles
without LA.29

tration. In addition, in patients with LBP, the press needles
reduced the subjective evaluation of LBP compared withthe placebo (P<0.05). In phase 2, the VAS results
indicated that LBP was reduced signiﬁcantly more in thepress needle group than in the LA group (P<0.05).

Applicability or Efficacy (Phase 1)
Figure 2 shows the trial proﬁle. Phase 1 ran from
December 12, 2007 to January 11, 2008, and phase 2 ranfrom January 30 to March 7, 2008. For phase 1, the 90
participants were randomly allocated to either the press
needle group (45 cases) or the placebo group (45 cases).
Of the 45 participants in the press needle group, 3 dropped
out, 1 due to medical treatment and 2 for personal reasons(1 for a sports competition and 1 unknown). Of the 45
participants in the placebo group, 6 dropped out, 3 due to
medical treatment and 3 for personal reasons (2 for sports
competitions and 1 unknown). The data for the remaining
42 participants in the press needle group and 39 participants in the placebo group were analyzed.
Table 1 shows the baseline characteristics of participants in the 2 study groups. The baseline characteristics
were similar in both groups.
Table 2 shows the results concerning the perception ofpenetration. Four participants (9.5%) in the press needle
group (n = 42) and no participants (0.0%) in the placebogroup (n = 39) reported a perception of penetration.
No participants (0.0%) in the press needle group and 1
participant (2.6%) in the placebo group reported experiencing de qi (dull sensation). Seven participants (16.7%) in
the press needle group and 5 participants (12.8%) in the

252 students
162 excluded

Statistical Analysis
The allocation of study participants was performed
by Seirin Corporation in a randomized manner using arandom number generating program (Microsoft Excel). At
the time of allocation, baseline data for the participants
were gathered from information obtained in advance andwere compared between the 2 groups (press needle andplacebo). On the basis of an earlier study, we calculated
that the necessary sample size was 38 or more cases pergroup.8
Furthermore, participants were stratiﬁed according totheir LBP status, because the presence or absence of LBP
was expected to have a considerable eﬀect on the outcome.
We analyzed eﬃcacy using the variation in the VAS scores(diﬀerence from baseline measurements) as the dependent
variable in a 3-way analysis of variance, with the factors of
LBP (presence or absence), time (baseline, immediately
after, or 20 min after) and intervention (press needle orplacebo). We used Fisher exact test for other intergroupdiﬀerences in ratios, and a t test for the diﬀerence in means.
We set the level of signiﬁcance at 5% for all analyses. All
statistical analyses were performed using SPSS (version
11.0J for Windows).

134 participants had experience
with acupuncture
28 non-compliance
90 randomised

45 allocated45 allocatedPress needle group

Placebo group

3 excluded

6 excluded

1 physical reason

3 physical reasons
3 noncompliance

2 noncompliance
42 analyzed

39 analyzed

Phase 2

9 LBP

participants

33 healthy

participants

5 LBP

34 healthy

participants

participants

Phase 1

(without LA)
1 excluded
1 noncompliant
8 analyzed(with LA)RESULTS
Short Summary of the Main Findings
In phase 1, intergroup comparisons showed nosigniﬁcant diﬀerences concerning the perception of pene-

440 | www.clinicalpain.com

FIGURE 2. Trial flowchart. LBP patients were those having LBP
for several days, having LBP at the time of baseline examination,and having a history of LBP for 6 months. LA indicates local
anesthesia; LBP, low back pain.
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Clin J Pain  Volume 25, Number 5, June 2009

Applicability of Press Needles to a Double-blind Trial

TABLE 1. Baseline Characteristics

Press Needle Group (n = 42)
VariableAge (years)
LBP*
LBP score (VAS)w
Duration of LBPz
Days per month with
LBPy
RDQJ
Height (cm)Weight (kg)Body mass index
Sitting height (cm)Sit-and-reach test (cm)Placebo Group (n = 39)

LBP Patients(n = 9)Healthy Participants(n = 33)

LBP Patients(n = 5)

Healthy Participants(n = 34)

20.78 (0.44)
6 (66.67)
35.56 (21.50)
4.67 (1.87)
1.89 (1.17)

20.88 (0.82)
0 (0.00)
11.59 (19.90)
1.66 (2.77)
0.53 (1.02)

21.00 (0.71)
3 (33.33)
35.40 (19.97)
3.60 (2.70)
1.80 (0.84)

20.56 (0.66)
0 (0.00)
9.73 (12.21)
1.16 (2.17)
0.39 (0.90)

0.44 (0.73)
178.50 (9.12)
72.30 (8.78)
22.71 (2.46)
95.07 (3.74)
47.06 (11.87)

0.67 (1.45)
174.31 (6.57)
69.74 (8.16)
22.91 (2.01)
93.59 (2.87)
42.97 (8.68)

2.22 (1.10)
175.22 (8.69)
76.54 (8.88)
25.05 (3.64)
93.36 (3.47)
41.96 (10.73)

0.74 (3.25)
173.09 (7.47)
68.59 (9.51)
22.88 (2.74)
92.94 (3.78)
42.27 (9.71)

Data are shown as numbers (%) for LBP and mean ( ± SD) for the other variables.
*The number of patients with LBP during the past several days.
wVAS: 0-100.
zTen response categories (0: no pain, 1: <1 wk, 2: Z1 wk and <1 mo, 3: Z1 moand <3 mo, 4: Z3 mo and <6 mo, 5: Z6 mo and <1 y, 6: Z1 y and<5 y, 7: Z5 y and <10 y, 8: Z10 y and <20 y, 9: 20 y).
yFive response categories; 0 = no pain, 1 = 1 to 3 days, 2 = 4 to 6 days, 3 = 7 to 14 days, 4 = 15 days or more.
JRDQ, range: 0 to 24.
LBP indicates low back pain; RDQ, Roland-Morris Disability Questionnaire; VAS, visual analog scale.

placebo group felt that they had received acupuncture using
a real needle. Intergroup comparisons showed no signiﬁcant diﬀerences.
Table 3 shows the mean pain scores at the time ofneedle penetration. The press needle group had a mean
total intensity score (based on the short form of the McGill
Pain Questionnaire) of 0.10 ( ± 0.43), and the placebogroup had a mean score of 0.10 ( ± 0.50). The press needle
group had a mean VAS of 1.67 ( ± 5.21), and the placebogroup had a mean score of 1.18 ( ± 2.62). The press needle
group had a mean present pain intensity of 0.05 ( ± 0.22),
and the placebo group had a mean score of 0.03 ( ± 0.16).
Intergroup comparisons showed no signiﬁcant diﬀerences.
Using diﬀerences in VAS values for LBP at the 3
points (baseline, immediately after, and 20 min after) as thedependent variable, we conducted a 3-way analysis of

TABLE 2. Participants’ Perception of Penetration and Dull
Sensation

Felt
Penetration
Press needle group
Placebo
Total
Dull sensation(De qi)Press needle group
PlaceboTotal

Did not
Could notFeel
Discriminate Total

4
0
4

38
37
75

0
2
2

42
39
81

0
1
1

35
33
68

7
5
12

42
39
81

Penetration was assessed using responses to the following question:‘‘How did you feel when the acupuncture needle was inserted?’’
Penetration: no signiﬁcant diﬀerences were observed between the press
needle and a placebo (Fisher exact test, P = 0.074).
Dull sensation (De qi): no signiﬁcant diﬀerences were observed between
the press needle and a placebo (Fisher exact test, P = 0.493).

r 2009 Lippincott Williams & Wilkins

variance with the factors of LBP (LBP patients vs. healthy
participants, where LBP patient may have had LBP for
several days, LBP at the time of baseline examination, or ahistory of LBP for 6 mo), time (baseline vs. immediately
after vs. 20 min after), and intervention (press needle
vs. placebo; Fig. 3). The results were as follows: [LBPtime–intervention: F(2,227) = 1.62, P = 0.200; LBP-time:F(2,227) = 1.92, P = 0.149; LBP-intervention: F(1,227) = 6.47,
P = 0.012; time-intervention: F(2,227) = 0.66, P = 0.520;
LBP: F(1,227) = 5.27, P = 0.023; time: F(2,227) = 10.26,
P<0.001; and intervention: F(1,227) = 2.13, P = 0.146].
As the LBP-intervention interaction was signiﬁcant,we conducted tests for the simple main eﬀect, and foundthat the simple main eﬀect of intervention was signiﬁcant inpatients with LBP [F(1,227) = 4.79, P = 0.030<0.05]. This
indicates that the press needles reduced the subjective
evaluation of LBP (VAS) to a greater degree than theplacebo. In addition, the simple main eﬀect of LBP was
signiﬁcant in the press needle group [F(1,227) = 15.33,
P<0.001].
This ﬁnding indicates that patients with LBP in thepress needle group experienced a greater reduction in theirsubjective evaluation of LBP than those without LBP. As
the simple eﬀect of time was signiﬁcant, we conducted amultiple comparison (Bonferroni) and found signiﬁcantdiﬀerences in the comparisons of baseline versus immediately after (P<0.001) and baseline versus 20 minutes after(P<0.001), but no signiﬁcant diﬀerences in the comparisonof immediately after versus 20 minutes after. A similar
analysis limited to patients with LBP in the press needle
group showed signiﬁcant diﬀerences in the comparisons ofbaseline versus immediately after (P = 0.014<0.016) andbaseline versus 20 minutes after (P = 0.004<0.016), but nosigniﬁcant diﬀerences in the comparison of immediately
after versus 20 minutes after.
Table 4 summarizes the number of side eﬀects. Only 1
participant in the press needle group developed a side eﬀect(sleepiness).
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Miyazaki et al

TABLE 3. Variables Concerning Patients’ Pain (Mean ± SD)

VariablePress Needle
Group (n = 42)

Placebo Group(n = 39)Py

0.10 ± 0.43
1.67 ± 5.21
0.05 ± 0.22

0.11 ± 0.51
1.21 ± 2.65
0.03 ± 0.16t(78) = 0.10, NS
t(79) = 0.50, NS
t(79) = 0.52, NS

SF-MPQ*
Total intensity scores
VASw
PPIz

*SF-MPQ, short-form McGill Pain Questionnaire, 15 pain descriptors rated on an intensity scale as
0 = none, 1 = mild, 2 = moderate or 3 = severe; range: 0 to 45.
wRange: 0 to 100.
zRange: 0 to 5.
yTwo sample t test.
NS indicates not signiﬁcant; PPI, present pain intensity; SF-MPQ, short form of the McGill Pain
Questionnaire; VAS, visual analog scale.

Mechanism (Phase 2)
As patients with LBP in the press needle groupexperienced a greater reduction in their subjective evaluation of LBP, we conducted additional analyses using 8 of
the 9 patients who had LBP and received press needle
insertion; we used the LA group as a control (press needle
insertion after LA treatment) and compared it with thepress needle group (press needle insertion without LA treatment; Fig. 4). We found that the VAS scores for LBP weresigniﬁcantly lower in the press needle group than in the LAgroup (paired t test: t = 2.86, P = 0.024 <0.05, 2-tailed).

DISCUSSION
The results indicate that a methodology using the press
needle and a placebo (the same device but lacking theneedle element) is suitable for double-blind testing. In
addition, we conﬁrmed the safety of press needles, as they10

VAS (mm)

0

-10

-20

Press needle (healthy participants) (n=33)
Placebo (healthy participants) (n=34)
Press needle (LBP participants) (n=9)
Placebo (LBP participants) (n=5)
baseline

immediately
after

20 minafter

FIGURE 3. Changes in VAS score for LBP. Verticle bars represent
the mean ± 1 SD. LBP indicates low back pain; VAS, visual analog
scale.

442 | www.clinicalpain.com

did not cause pricking pain among participants (patients)
and resulted in almost no adverse eﬀects. Our ﬁndings arelimited to the BL23 acupoint, so we are unable to conﬁrm
the eﬃcacy of the press needles at other single or multiple
acupoints; further studies may be necessary.
As we showed the eﬃcacy of this methodology in a
double-blind setting, we were able to conﬁrm the speciﬁc
eﬀect of metal (acupuncture) penetration of the skin at the
acupoint site. We only observed this eﬀect among patientswith LBP, and thus the BL23 acupoint seems to have a
speciﬁc eﬀect on LBP. This ﬁnding supports the use of
BL23 as an acupoint in clinical practice. However,acupuncture treatment of BL23 alone may not cure LBP,
and actual clinical treatment may require using a combination of multiple acupoints. Concomitantly, the changes weobserved in VAS values for LBP were not great enough to
be considered clinically eﬀective. In addition, we did not
track the duration of this eﬀect.
The use of topical anesthetic treatment as a control is a
new research methodology, and previous research has
identiﬁed problems such as the absorption characteristics
of anesthetics.30 However, these issues did not aﬀect thisstudy because we used only one acupoint, the depth ofpenetration was as small as 0.6 mm, and the study focusedon short-term eﬀects.
The mechanism for the analgesic eﬀect of acupunctureis thought to involve small-diameter aﬀerent nerves, but
studies have not yielded suﬃcient consistent evidence.31–33
Most studies in this ﬁeld have focused on acupuncture
methods and the resultant de qi, or on electroacupuncture.
Almost all physiologic studies that have been conducted onsuperﬁcial stimulation involve de qi, that is, shallow
needling and contact needling. This study is among theﬁrst to show the lack of an analgesic eﬀect under topicalanesthesia, thereby conﬁrming the involvement of smalldiameter aﬀerent nerves in the mechanism for the analgesic
eﬀect of superﬁcial stimulation that does not achieve de qi.
With respect to the types of small-diameter aﬀerent
nerves, researchers have proposed the possibility of
the induction of ‘‘limbic touch’’ through C ﬁbers,34 andthe possibility that suppression at the posterior horn of the
spinal cord may reduce the pain transmitted from the same
segment of spinal cord through Ab ﬁbers.32 These issues arebeyond the scope of this study. Additionally, it is necessary
to consider the possibility of a ‘‘placebo eﬀect,’’ because
the patients could recognize having received anestheticr 2009 Lippincott Williams & Wilkins

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Applicability of Press Needles to a Double-blind Trial

TABLE 4. Number of Side Effects in the Study

Press Needle Group (n = 42)
Side Eﬀects

20 minAfter

Immediately
After

20 min
After

0
1
0
0
0
0
0
0
0

0
1
0
0
0
0
0
0
0

0
0
0
0
0
0
0
0
3

0
0
0
0
0
0
0
0
2

Fatigue or malaise
Sleepiness
Aggravation of complaint
Itching in the puncture region
Dizziness
Nausea or vomiting
Hemorrhage
Pain in the puncture region
Discomfort in the puncture
regiontreatment. Further study would be necessary to verify thispoint, and we hope to see advances in this research.
In conclusion, this study showed that the press needle
and a placebo were indistinguishable and suggested that thepress needle had a speciﬁc inﬂuence in patients with LBP.
These ﬁndings imply that the use of the press needle
and a placebo can provide an eﬀective means of realizing
a double-blind setting for clinical studies of acupuncture.
Further studies using other acupoints are necessary toverify these ﬁndings and their external applicability.

VAS (mm)

5

0

*
-5

-10
baseline

immediately
after

FIGURE 4. Comparison between the control LA group (press
needles inserted after LA treatment for 30 min) (*), and the press
needle group (press needles inserted without LA treatment) (*).
Participants in the control LA group and press needle group were
those with LBP in phase 1 (n = 8). In the phase 2, after at least a
4-week washout period, a topical anesthetic patch was appliedfor 30 minutes to 8 participants from phase 1, to block the
peripheral nerve fibers before the insertion of the press needles.
Differences in VAS scores at 2 points were compared between
the 2 groups, using a paired t test [t(7) = 2.86, P = 0.024<0.05(2-tailed)]. Vertical bars represent the mean ± 1 SD. *P<0.05.
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Placebo Group (n = 39)

Immediately
After

ACKNOWLEDGMENT
The authors thank Dr Toshihiko Katafuchi from the
Department of Integrative Physiology at the Graduate
School of Medical Sciences, Kyushu University, for advice
about the neurophysiology of acupuncture.
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