A literature review of de qi in clinical studies.

OBJECTIVES: De qi is a sensation experienced by a patient or an acupuncturist during acupuncture treatment. Although de qi is considered to be important in acupuncture treatment, there are not many studies about de qi and its character. The purpose of this study is to review de qi questionnaires and evaluate the relationship between de qi and acupuncture points, stimulation and treatment effects.
METHODS: A search was conducted using three English-language databases (PubMed, Cochrane and ScienceDirect) and seven Korean databases with the keywords 'de qi' and 'needle sensation'. The included studies were then categorised as following: (1) de qi measurement tools, (2) the relationship between de qi and acupuncture points, (3) the relationship between de qi and stimulation, (4) the relationship between de qi and treatment effects and (5) attitudes and opinions toward de qi.
RESULTS: Several questionnaires have been developed to evaluate de qi, and the most frequent sensation in those questionnaires was 'heavy' and 'numb'. Although a few studies showed specificity to acupuncture points, information is still lacking to be able to draw a clear conclusion about the relationship between de qi and acupuncture points. Also, greater de qi was elicited in real acupuncture than placebo acupuncture in many studies. The relationship between de qi and treatment effects was controversial.
CONCLUSIONS: It seems that real acupuncture induced greater de qi than sham acupuncture, and the relationship between de qi, acupuncture points and treatment effects was controversial. However, the current literature evaluating de qi is not sufficient to derive clear conclusions. Further studies with more objective indices and rigorous methodologies are needed.

Introduction

Acupuncture is a treatment method that has been used in East Asia for thousands of years, and in recent years has been increasingly adopted worldwide.1 2 Acupuncture has proven to be effective for several diseases and symptoms, including osteoarthritis3 and vomiting.4 5 The mechanism of acupuncture may involve a form of ‘energetic’ phenomenon, such as the flow of energy through channels known as ‘meridians’.

The term ‘de qi’ means ‘arrival of qi’. De qi is a sensation experienced by a patient or an acupuncturist during acupuncture treatment.6 Typically, de qi is described as suan (aching or soreness), ma (numbness or tingling), zhong (heaviness) and zhang (fullness/distension or pressure).7 However, many sensations have been used to describe de qi in previous questionnaires, and it is still difficult to describe de qi clearly. For example, sharp pain is sometimes viewed as an abnormal reaction to acupuncture treatment and sometimes as a part of de qi.

De qi is considered to be an important variable in acupuncture, because there is a belief that achieving de qi is associated with positive outcomes in acupuncture treatment.8 9 However, a relationship between de qi and the positive effects of acupuncture treatment remains unproven in clinical trials,10–13 and the mechanisms underlying this sensation are largely unknown. Additionally, there is a lack of adequate experimental data indicating de qi and related factors including acupuncture points, needling techniques and nerve fibre systems.14

In this study, we reviewed de qi related literature: (1) to investigate which sensations are used in de qi questionnaires, (2) to determine the relationship between de qi and acupuncture points, (3) to determine the relationship between de qi and stimulation, (4) to determine the relationship between de qi and treatment effects and (5) to learn the attitudes and opinions toward de qi.

Materials and methods

A search was conducted using English-language (PubMed, Cochrane and ScienceDirect) and Korean (Research Information Sharing Service, Korean Studies Information Service System, Korean Medical Database, DBPIA, the Korean Oriental Medical Society, the Korean Acupuncture & Moxibustion Society, Society of Meridian & Acupoint) databases with the keywords ‘de qi’ and ‘needle sensation’. Additional searches were performed on the references of the obtained studies. Only the human studies from the search results were included. The included studies were then categorised by the following criteria: (1) de qi measurement tools, (2) the relationship between de qi and acupuncture points, (3) the relationship between de qi and stimulation, (4) the relationship between de qi and treatment effects and (5) attitudes and opinions toward de qi.

With regard to the tools for assessing needle sensations or de qi, only those studies in which the researchers developed a questionnaire using a qualitative or quantitative method were included. The studies that extracted the corresponding items from the existing literature or that did not describe the development method of the questionnaire were excluded.

The ‘de qi and acupuncture points’ category included studies evaluating the differences in de qi associated with acupuncture points and non-acupuncture points, and the ‘de qi and stimulation’ category included studies dealing with the differences in de qi originating from different types of stimulation, such as real needles and sham needles. The ‘de qi and treatment effects’ category included studies addressing the relationship between de qi and the treatment effects of acupuncture treatment, and the final category addressed the attitudes of the patient and the practitioner toward de qi.

Results

Questionnaires on needle sensations or de qi

The first attempt to measure needle sensation was the Acupuncture Sensation Scale (ASS) developed by Vincent et al.15 McGill developed a pain questionnaire16 and Vincent subsequently developed the ASS based on McGill's questionnaire after consulting with 10 acupuncturists. The ASS included 20 items for acupuncture sensation: sharp, pulling, electric, tingling, heavy, pulsing, spreading, pricking, aching, hot, dull, radiating, numb, shocking, hurting, burning, stinging, penetrating, intense and throbbing.

The ASS was translated into Korean to compare the patients’ expectations of needle sensation with their actual experience. According to this study, more than 60% of 38 patients expected painful, penetrating, sharp, tingling, pricking and stinging sensations but actually frequently experienced aching, spreading, radiating, pricking and stinging.17 In a later study conducted by the same authors to examine whether the past treatment experience affected the expectation of needle sensation, the most common sensation that subjects experienced were sharp, intense, radiating and heavy.18

As a part of an effort to develop a sham acupuncture device, Park et al19 assessed de qi using 25 questions derived from Vincent's survey. In addition to the 20 ASS items, this questionnaire included pressure, boring, pinching, tender and flickering sensations. Macpherson and Asghar20 divided the 25 needle-sensation items in this questionnaire into de qi-related sensations and pain-related sensations using feedback from 20 experts. The seven sensations related to de qi were aching, dull, heavy, numb, radiating, spreading and tingling, and the nine sensations related to acute pain were burning, hot, hurting, pinching, pricking, sharp, shocking, stinging and tender.

To assess needle sensation, Kong et al11 developed the Subjective Acupuncture Sensation Scale (SASS). This scale consisted of nine items selected based on the literature and experience (tingling, heavy, aching, numb, burning, throbbing, stabbing, fullness and soreness), one freeform patient sensation item and another item measuring anxiety. This scale was later revised into the Massachusetts General Hospital Acupuncture Sensation Scale (MASS) for more scientific application.21 The MASS consists of 12 de qi-related sensations (soreness, aching, deep pressure, heaviness, fullness/distension, tingling, numbness, sharp pain, dull pain, warmth, cold and throbbing) and a freeform patient sensation item. The degree of anxiety before, during and after the acupuncture treatment was also included via a mood scale. In addition, the extent of needle sensation spread, which had not appeared in previous scales, was included an accessory measure.

Qualitative methods, such as interviews or surveys, were also used to develop de qi questionnaires. Leung et al22 interviewed 15 subjects and investigated the 16 sensations most frequently felt by patients. Also, a Chinese study developed a de qi survey consisting of 12 items by survey of 200 subjects.23 The most common needle sensations in this study were distension, soreness, electrical sensations and numbness.

White et al24 developed the Southampton Needling Sensation Questionnaire using patient interviews, expert consensus and a combination of clinical experience and knowledge of the literature. After this survey was developed, the data from 227 patient surveys were analysed. Of 17 items, 14 sensations were classified into ‘aching de qi’ and ‘tingling de qi’. Deep ache, dull ache, discomfort, heaviness, pressure, bruising and stinging were classified as ‘aching de qi’, and tingling, warmth, spreading, fading, numbness, twinges and throbbing were classified as ‘tingling de qi’. Whereas ‘aching de qi’ was significantly correlated with the overall pain of acupuncture, ‘tingling de qi’ was not. Of the other three items, ‘sharp’ is related solely to pain, and ‘cold’ and ‘itchy’ did not load into any factor.

Recently, a de qi questionnaire considering the phase of acupuncture treatment was developed.25 The Acupuncture Sensation Questionnaire (ASQ) did not use the conventional method of a single time-independent assessment; instead, it assessed sensations experienced during needle insertion, manual stimulation and needle retention. The ASQ includes 19 items: 3 for needle insertion, 9 for manual stimulation and 7 for needle retention. The three needle-insertion items are refreshing or relieving, dullness and numbness. The manual stimulation items are spreading out, refreshing or relieving, warm, dull, activated digestion with bowel moving, relieving sensation of tense or tight muscles, heavy, numb and gentle touch. The needle-retention items are warm, refreshing or relieving, surging opening flow of stuffed or choked feeling, spreading out, heavy, activated blood circulation and compressing or pressuring.

As a result of reviewing de qi questionnaires, 8 questionnaires were included with 46 sensations. Among those sensations, heavy and numb were included in all eight questionnaires. Also, sharp, tingling, dull, throbbing sensations were included in more than five questionnaires (table 1).

Table 1

The sensations described in acupuncture sensation questionnaires

	Vincent et al15	Park et al19	Kong et al11	Kong et al21	Leung et al22	Mao et al23	White et al24	Kim et al25	N*
Sharp	X	X		X	X	X	X		6
Pulling	X	X				X			3
Electric	X	X				X	X		4
Tingling	X	X	X	X	X	X	X		7
Heavy	X	X	X	X	X	X	X	X	8
Pulsing	X	X			X				3
Spreading	X	X					X	X	4
Pricking	X	X					X		3
Aching	X	X	X	X	X				5
Hot	X	X							2
Dull	X	X		X	X	X	X	X	7
Radiating	X	X							2
Numb	X	X	X	X	X	X	X	X	8
Shocking	X	X							2
Painful	X	X							2
Burning	X	X	X		X	X			5
Stinging	X	X					X		3
Penetrating	X	X							2
Intense	X	X							2
Throbbing	X	X	X	X	X	X	X		7
Pressing		X		X	X		X		4
Boring		X							1
Pinching		X							1
Tender		X							1
Flickering		X							1
Cool/cold				X	X				2
Stabbing			X						1
Fullness/distension			X	X		X			3
Soreness			X	X		X			3
Warmth				X	X	X	X	X	5
Twitching					X				1
Muscle contraction					X				1
Tapping					X				1
Pecking					X				1
Bruising							X		1
Twinge							X		1
Uncomfortable							X		1
Fading							X		1
Deep ache							X		1
Refreshing or relieving/activated digestion with bowel movements/relieving sensation of tense or tight muscle/gentle touch/surging opening flow of stuffed or choked feeling/activated blood circulation/compressing or pressing								X	1

N*, Number of being used in de qi questionnaire of each sensation

The relationship between de qi and acupuncture points

In a study by Vincent et al,15 patients assessed needle sensations after acupuncture needles were applied to acupuncture points and non-acupuncture points of the hands, feet and legs. In that study, there were no significant differences in needle sensations between acupuncture points and non-acupuncture points for any locations. However, Roth et al26 reported that needle sensation was significantly stronger with traditional needling than sham acupuncture using a non-acupuncture point.

Park et al27 applied needles at acupuncture and non-acupuncture points with four different depths (the epidermis, corium, fascia and muscle), and the needle sensations for each stimulation were assessed using the Southampton needle sensation questionnaire. The results showed that there were no statistically significant differences between acupuncture point and non-acupuncture point needle sensations at the epidermis, corium and fascia levels, although there were differences at the muscle level. Another recent study reported that soreness, numbness, distension and heaviness are felt when a needle is applied to the SJ5 acupuncture point, whereas a tingling sensation is mostly felt when a needle is applied to non-acupuncture points.28

As well as the difference between acupuncture points and non-acupuncture points, the peculiarity of each acupuncture point has also been studied. A Chinese study investigated needle sensations after needles were applied to pairs of acupuncture points with different meridians, nerves, or tissues. Although there was no significant difference in the prevalence of needing sensations between the two paired acupuncture points, significant intensity differences were seen for soreness, fullness and heaviness. Also, the tingling sensation was stronger than heaviness and pressure at acupuncture points PC6, PC7 and ST36 compared to CV4 (table 2).29

Table 2

Characteristics of studies including the relationship between de qi and acupuncture point

Lead author (year)	Participants	Sample size	Intervention	Outcome	Results
Vincent et al (1989)15	Healthy volunteers	65	(A) Acupuncture points	Questionnaire including 20 sensations	De qi was not significantly different between (A) and (B)
			(B) Non-acupuncture points
Roth et al (1997)26	Healthy volunteers	20	(A) Acupuncture points	Questionnaire including more than four sensations	De qi was significantly stronger in (A) than (B)
			(B) Non-acupuncture points
Park et al (2011)27	Healthy volunteers	5	(A) Acupuncture points	Southampton needle sensation questionnaire (including 17 sensations and 1 pain VAS)	Groups (A) and (B) were not significantly different at epidermis, corium and fascia, although there was a significant different at muscle level
			(B) Non-acupuncture points with four different depths (epidermis, corium, fascia, muscle)
Zhang et al (2011)28	Healthy volunteers	18	(A) Acupuncture point (SJ6)	Questionnaire including four sensations	Group (A) showed soreness, numbness, distension, heaviness
			(B) Non-acupuncture point		Group (B) showed tingling sensation
Zhou et al (2011)29	Healthy volunteers	21	Electroacupuncture was applied at paired acupuncture points with different meridian, nerves, or tissues	Questionnaire including nine de qi sensations, sharp pain, and any other sensations	Two paired points were not significantly different in prevalence of needling sensation, but several paired acupuncture points showed significant intensity differences in soreness, fullness, heaviness

VAS, visual analogue scale.

The relationship between de qi and stimulation

Kong et al11 compared needle sensations before and after manual acupuncture, electroacupuncture and sham acupuncture stimulations. The results showed that the de qi from manual acupuncture was not significantly different from that of electroacupuncture, but that the de qi from sham acupuncture was significantly lower than that of manual acupuncture or electroacupuncture. In another study of the effects of three different stimulation types (electrode, manual acupuncture and electroacupuncture), the de qi from electroacupuncture was greater than that of manual acupuncture or electrode acupuncture.22 Additionally, whereas tingling was the most common sensation for electric stimulations resulting from electrodes or electroacupuncture, aching was the most common sensation for manual acupuncture. Chae et al30 assessed and compared the de qi when using real acupuncture, blunted-tip sham acupuncture and round-tip sham acupuncture; the real acupuncture group exhibited significantly higher needle sensation index scores than did the blunted-tip and round-tip sham acupuncture groups. With deep penetration and needle rotation, real needles produced statistically significantly greater de qi than did sham acupuncture with no penetration13 31 or sham acupuncture with superficial needling only.32

There are studies that show the difference in de qi aspect depends on the kind of acupuncture or stimulation. Comparing the needle sensations from pharmacopuncture and placebo acupuncture, the results showed that there were statistically significant differences between normal saline placebo acupuncture and Hwangryunhaedoktang herbal acupuncture in seven items: aching, pricking, stinging, heaviness, dullness, numbness and pulsing. There were also significant differences between normal saline acupuncture and Hominis Placenta herbal acupuncture in dullness and coolness.33 In Hui et al's14 comparison of the de qi from tactile stimulation and acupuncture, acupuncture showed significantly higher frequency and intensity of sensation than did tactile stimulation in aching, soreness and pressure. Kou et al34 also conducted acupuncture treatment with real needles or placebos and used five visual analogue scale items (numbness, pressure, heaviness, warmth and radiating paraesthesia) to evaluate de qi. The results showed that acupuncture produced significantly higher numbness, pressure, warmth and radiating paraesthesia sensations, but not heaviness, than the placebo needle did.

One recent study reported that superficial penetration produces prominent pricking and sharp sensations, whereas deep penetration produces a high degree of deep, dull, heavy, spreading and electric shock sensations.27 Deep, dull and heavy sensations were more prominent when needle rotation was used than when simple needle insertion was employed.

In contrast to the studies discussed above, however, several studies have reported no difference between real needles and sham needles. Salih et al35 conducted a study comparing de qi after real and sham-laser acupunctures and found that spreading, radiating, tingling, tugging, pulsing, warm and dull were the sensations most frequently experienced by both groups. The results also indicated that real acupuncture and sham-laser acupuncture produced de qi that was similar in terms of frequency, intensity and quality. The study found that de qi can be felt even with no tactile skin stimulation, which suggests that such de qi results from the overall treatment process and not necessarily from a particular aspect of it (table 3).

Table 3

Characteristics of studies including the relationship between de qi and stimulation

Lead author (year)	Participants	Sample size	Intervention	Outcome	Results
De qi intensity
Kong et al (2005)11	Healthy subjects	31	(A) Manual acupuncture	SASS (nine sensation and one freeform, anxiety measure)	Groups (A) and (B) were not significantly different
			(B) Electroacupuncture
			(C) Sham manual		Group (C) was lower than (A) or (B)
Leung et al (2006)22	Healthy subjects	15	(A) Electrode	Questionnaire including 16 sensations	Group (C) was greater than (A) or (B)
			(B) Manual acupuncture		In (B), aching was the most common sensation
			(C) Electroacupuncture		In (A) and (C), tingling was the most common sensation
Chae et al (2006)30	Healthy volunteers	94	(A) Real acupuncture	ASS (including 20 sensations)	Group (A) was higher than (B) and (C)
			(B) Blunted-tip sham acupuncture
			(C) Round-tip sham acupuncture
White et al (2010)13	Patients with osteoarthritis	147	(A) Real acupuncture with deep penetration and needle rotation	Questionnaire including 25 sensations	Group (A) produced significantly greater de qi than (B)
			(B) Sham acupuncture with no penetration
Benham et al (2010)32	Healthy volunteers	15	(A) Real acupuncture with deep penetration and needle rotation	Needle sensation VAS and SASS (nine sensation and one freeform, anxiety measure)	Group (A) was significantly greater than (B)
			(B) Sham acupuncture with superficial needling
Chen et al (2012)31	Healthy volunteers	24	(A) Acupuncture at acupuncture points	Questionnaire including six sensations	Group (A) produced de qi, (B) produced de qi or sharp pain. Group (C) showed sharp pain and (D) showed nothing.
			(B) Acupuncture at sham acupuncture points
			(C) Sham acupuncture at acupuncture points
			(D) Sham acupuncture at sham acupuncture points
De qi aspect
Yoon et al (2004)33	Healthy volunteers	63	(A) Hwangryunhaedoktang herbal acupuncture	Questionnaire including 21 acupuncture sensations	Groups (A) and (C) were significantly different for seven sensations (aching, pricking, stinging, heaviness, dullness, numbness, pulsing)
			(B) Hominis placental herbal acupuncture		Groups (B) and (C) were significantly different for two sensations (dullness and coolness)
			(C) Normal saline placebo acupuncture
Hui et al (2007)14	Healthy volunteers	42	(A) Acupuncture	Questionnaire including 10 sensations and sharp pain	Group (A) showed significantly higher frequency and intensity of sensation than (B) in aching, soreness and pressure
			(B) Tactile stimulation
Kou et al (2007)34	Healthy volunteers	11	(A) Real acupuncture	Questionnaire including five sensations	Group (A) showed higher VAS values for numbness, pressure and warmth, radiating paraesthesia than (B)
			(B) Placebo acupuncture (superficial, non-acupuncture points without manipulation)
Park et al (2011)27	Healthy volunteers	5	(A) Superficial penetration	Southampton needle sensation questionnaire (including 17 sensations and one pain VAS)	Group (A) produced greater sensation in pricking and sharp sensation, and (B) showed greater sensation in deep, dull, heavy, spreading and electric shock sensation
			(B) Deep penetration		Needle rotation in (B) increased deep, dull and heavy sensations
Salih et al (2010)35	Healthy volunteers	34	(A) Real laser acupuncture	Questionnaire including 17 sensations	Groups (A) and (B) resulted in similar de qi sensations with regard to frequency, intensity and quality.
			(B) Sham laser acupuncture

ASS, acupuncture sensation scale, SASS, subjective acupuncture sensation scale, VAS, visual analogue scale.

The relationship between de qi and treatment effects

Kong et al11 compared the degree of pain and needle sensations before and after acupuncture. The results showed statistically significant correlations between the pain-relieving effect and two of the nine SASS items (soreness and numbness). Chae et al10 also investigated the degree of acupuncture analgesia before and after acupuncture treatment and compared that with the ASS. Significant correlations between the analgesic effect of real acupuncture and the degree of acupuncture sensation were found with respect to burning, intense, pulsating and stinging sensations.

A Japanese study treated osteoarthritis with real and sham needles and found that patients who felt de qi experienced better treatment results than those who did not.12 However, another two clinical studies comparing the de qi and pain relief of patients with osteoarthritis found no significant difference in pain relief between those who felt de qi and those who did not (table 4).13 36

Table 4

Characteristics of studies including the relationship between de qi and treatment effects

Lead author (year)	Participants	Sample size	Condition	Intervention	Outcome	Results
Kong et al (2005)11	Healthy participants+experimental pain	31	Pain (heat stimuli)	Acupuncture	SASS (nine sensations and one freeform, anxiety measure)	Significant correlations of analgesia with the two sensations (soreness and numbness)
Chae et al (2007)10	Healthy volunteers+experimental pain	92	Pain	(A) Real acupuncture	Questionnaire including 20 sensations	In (A), there was a correlation between the analgesic effect of real acupuncture and the sensation (burning, intense, pulsating, stinging)
				(B) Sham acupuncture (non-penetrating needle)
Takeda and Wessel (1994)12	Patients with osteoarthritis	40	Pain	(A) Real acupuncture	McGill pain questionnaire including 75 sensations	Patients who felt de qi experienced better treatment results than those who did not
				(B) Sham acupuncture
White et al (2010)13	Patients with osteoarthritis	147	Pain	(A) Real acupuncture	Questionnaire including 25 sensations	No significant correlation between the strength of de qi and improvement in pain
				(B) Sham acupuncture (Streitberger needle)
Foster et al (2007)36	Patients with osteoarthritis	352	Pain and function	(A) Advice and exercise	Therapists recorded the sensations that participants reported	No significant differences in change scores for pain or function between participants reporting de qi during more than 50% of treatment sessions compared with those who reported de qi less often
				(B) Advice and exercise plus true acupuncture
				(C) Advice and exercise plus non-penetrating acupuncture

SASS, subjective acupuncture sensation scale, VAS, visual analogue scale.

Attitudes and opinions toward de qi

In a Chinese study that investigated the sensations and faith of patients in acupuncture, 89% of the patients reported that the needle sensations spread from the applied acupuncture points, and 82% considered the needle sensation to be an important element of acupuncture treatment.24 In addition, 68% of the patients thought that stronger needle sensations led to better treatment results, and 81% felt comfortable during the acupuncture treatment process.

In a survey of acupuncture practitioners in China and the USA, 47 of 86 practitioners agreed that dull pain was de qi, and over half agreed that de qi was beneficial, but sharp pain was harmful.37 Of them, 73% believed that the there was a correlation between de qi and treatment results. The patient attitudes toward de qi in China and the USA were found to follow different patterns; only 2 of the 17 practitioners who responded that patients approved of de qi were from the USA, and the remainder were from China.

Discussion

Most clinical studies of de qi assessed patient de qi by asking patients to record the sensations they feel or by making practitioners assess patient de qi based on patients’ reactions.19 However, many acupuncturists thought that the de qi felt by the practitioner was as important as the de qi felt by the patient.37 Kim38 also reported that the practitioner's needle sensations are more objective than those of patients and are necessary for obtaining treatment results. Even though there have been many attempts to assess the needle sensations experienced by the practitioner,19 39 a validated de qi questionnaire has not been confirmed. Further studies to develop tools assessing de qi based on the practitioner's feeling or senses should be conducted, and for that, various approaches considering the interaction between practitioners and patients and the historical meaning of de qi should be used.

A recent Austrian study used ultrasonic waves to measure the distance to nerve tissue when a needle was inserted at an acupuncture point and assessed whether de qi was felt when nerve tissue was contacted.40 Similarly, studies to investigate the reactions to acupuncture points are currently being conducted using fMRI. A Chinese study has found that fMRI results were different when the HT7 or SI6 acupuncture point was stimulated.41 Another recent study found that acupuncture at different acupuncture points could induce neural responses in different brain areas.42 Fang et al43 reported that rotating the needle strengthened the effect of acupuncture on cortical neuronal activity using fMRI. When objective indexes and de qi are assessed together, the relationships among tissue, activated brain areas and de qi will be clarified. These results could help to find out how de qi is elicited and the role of de qi in acupuncture treatment.

Even in situations of similar acupuncture or similar stimulation, the degree of de qi that the patients felt differed by individual.30 34 44 A study verifying the effects of acupuncture on emotions and cognition reported that soreness, a major element of de qi, was correlated with the degree of deactivation of the angular gyrus in women but not in men.45 Thus, de qi is not uniformly manifested in all patients but can differ by individual or gender. The reason that patients feel different de qi even with similar acupuncture treatments might be related to why people show different treatment effects or which factors elicit de qi. Therefore, it is important to investigate why the magnitude and the type of de qi that people feel is different. An assessment of de qi that considers individual characteristics and circumstances is also a future research goal.

Current de qi assessment tools confound all kinds of sensations related to needle. Just as the early ASS versions were based on the McGill pain survey, many early studies quantitatively assessed the sensation. However, one study reported that the acupuncture needle sensations of de qi and sharp pain are associated with different patterns of activations and deactivations in the brain.31 Also, in the previous studies, the analgesic effect of acupuncture showed correlation with several sensations including soreness, numbness,11 burning, intense, pulsating and stinging.10 Even though there was an attempt to classify needle sensations into de qi cluster and acute pain cluster,20 the sensation related to acupuncture effect is still not clear. In the future, additional studies should be conducted to elucidate which sensation is related to the therapeutic effect of acupuncture.

Conclusions

Several questionnaires have been developed to assess de qi, and most of those are based on patients’ experience. Also, the most frequent sensations in those questionnaires were ‘heavy’ and ‘numb’. Even though a clear relationship between de qi and acupuncture point was not shown, the level of de qi is usually greater in real acupuncture compared to sham acupuncture according to previous studies. The relationship between de qi and treatment effects is controversial. It is difficult to form a clear conclusion because of the lack of research on de qi. Further studies using more objective indexes and considering individual characteristics should be conducted.

We explored the literature on de qi.

It is largely inconclusive on many aspects.

De qi may be more easily elicited by EA than manual, and at some acupuncture points than non-points.