Developing a diagnostic checklist of traditional Chinese medicine symptoms and signs for psoriasis: a Delphi study

Psoriasis is a chronic, inflammatory, hyper-proliferative and immunologically mediated skin disease with a genetic basis [1]. It is characterized by erythema, defined as scaly plaques with itching and bleeding [2]. Psoriasis prevalence ranges from 0.6% to 4.8% in all age groups worldwide [3, 4] and psoriatic arthritis (PsA) affects 6–39% of all psoriasis patients [5‐7]. The variation in psoriasis prevalence with geographical and ethnic factors suggests an influence of the physical environment (e.g., climate) patterns or other exposures in the development of psoriasis [8‐10].

In Western medicine, psoriasis treatments can be any one or a combination of the three main modalities: topical treatments with steroids or other agents, UV therapy with or without light-sensitizing medication and systemic medications, such as retinoids, and cytotoxic drugs [11, 12]. Some psoriatic patients (51%) may also opt to use alternative therapies, such as herbal remedies, vitamin supplements, and dietary manipulation [13], and traditional Chinese medicine (TCM) [14].

According to TCM diagnosis [15], psoriasis (白疕, bai bi or white mange) [16] is considered to be due to (1) the invasion of pathogenic wind that incubates in the yin and blood; or (2) the accumulation and stagnation of qi (vital energy) and blood caused by emotional upset. It may also be caused by impairment or disharmony in the functioning of other organs and energy pathway channels [17]. In general, topical treatment, oral medication, and advice on lifestyle and environment are prescribed to relieve the lesions and the impairment or disharmony of the body.

TCM treatment is based on Zheng composition rather than disease definition [18, 19]. For the same disease, there are varieties of syndromes related to different climates and geographical factors [20].

Developing a consensual checklist of TCM symptoms and signs to aid identifying and classifying psoriasis would be useful for TCM clinical practice and scientific research. The Delphi method is a consensus methodology that attempts to assess the extent of agreement (consensus measurement) and to resolve disagreement (consensus development) in medical and health service research [21, 22]. The Delphi technique can be performed in 3 stages. First, the opinions of a group of experts are sought based on an anonymous self-administered questionnaire to eliminate the influence of peer pressure. Second, a feedback system is used to allow the respondents to compare their opinion against a statistical summary of the whole group. Finally, this process is repeated until the opinions are stable [23, 24]. Thus, using the Delphi method, experts can participate without geographic limitations, offer their opinions independently and confidentially without face-to-face meetings and change their opinion based on the systematic feedback from the results of the previous rounds in consecutive stages of the process [25].

This study aims to develop a consensual checklist using the Delphi method for psoriasis classification by TCM symptoms and signs.

Sixteen experts were recruited, seven from Beijing and nine from Yunnan provinces. The rating expectative panel of dermatologists in Beijing consisted of four males and three females, while in Yunnan it comprised five males and four females. Two experts were professors and five were associate professors in Beijing while seven experts were associate professors and two were professors in Yunnan province. The total age (mean ± SD) of the experts was 47.7 ± 4.9 years; 46.6 ± 4.8 years for those in Beijing, and 48.6 ± 5.2 years for those in Yunnan province.

Among 102 reports located in the literature, none was excluded since all mentioned symptoms, signs and Zhengs related to psoriasis. One hundred and thirty items were extracted and grouped into one of the following 8 domains: (1) skin lesion color; (2) type of skin lesion; (3) shape of skin lesion; (4) associated factors; (5) physical expression; (6) tongue and its coating; (7) pulse; and (8) living environment. All domains except the last were present in the initial checklist of the first round of the Delphi study, the 8th domain was added on expert suggestion in the second round.

From the literature and Delphi method, 96 items of TCM symptoms and signs were selected for psoriasis classification. Although the level of agreement among the experts was not perfect, a final checklist was developed.

Type, color and shape of the skin lesion were rated with the highest scores among the 8 domains. This was consistent with the Psoriasis Area Severity Index (PASI), which places strong weight on skin-related items [30].

Smoking and drinking are generally referred to as external pathogenic factors. Both past and current smokers have a higher risk of developing psoriasis and the risk increases with duration, intensity and pack-years of smoking [31]. These factors were included by the experts in our study.

Physical expression items contributed to as many as 30% of all items. Two viscera contributed seven items: Spleen-related items linked to gastrointestinal symptoms [32], and Liver-related items linked to mental health [33]. The Spleen group was not as strong as the Liver group in psoriasis symptoms based on TCM.

Itching is an important symptom in psoriasis that correlates with the severity of disease and is experienced by almost 85% of patients [34, 35]. It causes anxiety, distress and worsens the patients’ mental health [36]. In the final round, the number of itching items was the highest among physical expression items.

Only two orthopedic items, joint and muscle pain and stiffness with bending limitations, were included by the experts. This may be because arthritic complications of psoriasis are often treated by rheumatologists rather than dermatologists [37]. Symptoms of PsA may closely resemble other diseases including rheumatoid arthritis.

Tongue and its coating are often examined in TCM. Up to 8.2% of fissured tongue and 5.6% of geographical tongue were observed in psoriatic patients in Iran [38]. Tongue coating is associated with the depth of skin involvement. Tongue substance reflects excess or deficiency of qi, blood and viscera[39]. The manifestations vary over the long-term course of psoriasis. Seven tongue substances and 8 tongue coatings were included in the final checklist.

Pulse palpation is an important method to classify the syndrome of psoriasis. Slippery or rapid pulse reflects blood heat. Hesitant and deep pulse reflects blood stasis [40]. Seven types of pulse and its manifest frequency were included for psoriatic patients.

Certain types of symptoms and signs retained by the experts in the final checklist coincided with various known psoriasis risk factors, e.g., streptococcal infection, sore throat and female hormones [41, 42].

Environmental factors can influence psoriasis, e.g., coldness and low humidity. Psoriatic patients can recover more quickly in a hot or humid environment [43]. The presence of these four major environmental factors are related to external etiology factors, and are manifest in the symptoms and signs of psoriatic patients.

There was no obvious evidence of clustering of opinions by geographic setting of the experts. However, a strong conclusion of the similarity of their opinions could not be made since there were a limited number of expert informants. This standardized checklist was approved by psoriasis experts in two different regions of China and might be used throughout the whole of China.

The mean weighted Kappa statistics for the same rater in different rounds showed that raters agreed with themselves in the consecutive rounds. For example, a Kappa value of 0.34 between the first and the second rounds and 0.42 between the second and third rounds (Table 3). When the third round was reached, agreement with the second round was very high and stopping the Delphi process was justified since it was unlikely there would be further changes in the experts’ opinion even though it may have differed from that of the others. The low Kappa statistics in the last column of Table 3 and the low ICC values confirmed that experts did not agree with each other for many items. This implies that experts were unlikely to have achieved a high consensus in opinion even if more rounds had been performed [44]. Recommendations have previously been made for the number of rounds of the Delphi technique [45]. Four Delphi rounds were suggested by Sumsion [46]. However, two to three rounds are currently used, to avoid fatigue of the respondents [47]. Our findings confirm that more than three Delphi rounds would probably not be of further benefit. Table 4 shows the non-significant effect of round number on experts’ opinions, and demonstrates that participants did change their ideas a little when they saw the results in the first round but did not change their ideas in the subsequent rounds and overall agreement could not be better as rounds increased.

Even though Delphi is a good study design for achieving consensus among experts, a true consensus might not be met since it is a manipulated consensus based on a compromised position [48]. Even though they had the freedom to make comments, experts were unavoidably forced to follow the structural domains we proposed in the first round. It was also suggested that experts should be selected from a wide spectrum of vested interest [49]. However, we selected only those from Beijing and Yunnan on the basis of convenience and budget constraint. However, the dendrogram (Figure 1) shows that experts’ ideas were independent of their geographical working location. Even though some Delphi studies have recruited very large numbers of participants for the panel, some authorities suggest a panel of 7 to 12 and some suggest up to 10 to 50 at most [45, 50]. As mentioned above, fixation of experts’ idea was reached at the third round, and having too many informants in a panel may not be a good strategy to improve agreement among them.

The development of a checklist from a consensus of well-recognized experts in psoriasis in China, allows further research studies and clinical practice to be standardized. Furthermore, based on a standard list of symptoms and signs, diagnosis and treatment of psoriatic patients may be unified and variations in clinical practice among TCM doctors can be minimized.

A checklist containing 96 items of 8 domains was developed for classifying psoriasis with traditional Chinese medicine symptoms and signs.