Is indigo naturalis effective in treating patients with chronic plaque psoriasis?
Date of publication of the randomized controlled trial: November 2008
Design
Randomized controlled trial (RCT).
Participants
42 patients (mean age: 34.6 years, male %: 76.2%) with chronic plaque psoriasis, with clinical diagnosis made by 2 dermatologists.
Intervention
Indigo naturalis ointment (1.4% indigo) topically applied to psoriatic plaque lesions for 12 weeks.
Comparator
Comparison: Indigo naturalis ointment versus placebo ointment.
Major Outcomes
Outcome 1: Sum of the scores of scaling, erythema and induration of psoriatic lesions. Higher score indicates more severe psoriasis;
Outcome 2: Percentage of target plaque clearance. Lower percentage indicates better clearance.
Settings
This trial was performed in an outpatient setting.
Comparison    Indigo naturalis ointment versus placebo ointment
Main Results
Compared to placebo ointment, indigo naturalis ointment was significantly more effective in reducing scaling, erythema and induration of psoriatic lesion (p<0.001). It also had significant benefit in promoting clearance (p<0.001) among patients with chronic plaque psoriasis.
Comparison: Indigo naturalis ointment versus placebo ointment among patients with chronic plaque psoriasis
Outcomes No. of studies (Total number of participants) Mean score (SD)/ No. of participants Heterogeneity test ( I2) p value Overall quality of evidence*
Intervention Comparator
1 1 (42) 18.9 (2.97)/ 42 18.7 (3.08)/ 42 Not applicable as there is only 1 study. 0.21 Low
Comparison: Indigo naturalis ointment versus placebo ointment among patients with chronic plaque psoriasis
Outcomes No. of studies (Total number of participants) Mean %/ No. of participants Heterogeneity test (I2) p value Overall quality of evidence*
Intervention Comparator
2 1 (42) 38.5/ 42 90/ 42 Not applicable as there is only 1 study. <0.001 Moderate
Keys: SD = standard deviation.
Comparison    Indigo naturalis ointment versus placebo ointment
Main Results
Compared to placebo ointment, indigo naturalis ointment was significantly more effective in reducing scaling, erythema and induration of psoriatic lesion (p<0.001). It also had significant benefit in promoting clearance (p<0.001) among patients with chronic plaque psoriasis.
Comparison: Indigo naturalis ointment versus placebo ointment among patients with chronic plaque psoriasis
Outcomes 1
No. of studies (Total number of participants) 1 (42)
Mean score (SD)/ No. of participants Intervention 18.9 (2.97)/ 42
Comparator 18.7 (3.08)/ 42
p value 0.21
Overall quality of evidence* Low
Comparison: Indigo naturalis ointment versus placebo ointment among patients with chronic plaque psoriasis
Outcomes 2
No. of studies (Total number of participants) 1 (42)
Mean %/ No. of participants Intervention 38.5/ 42
Comparator 90/ 42
p value <0.001
Overall quality of evidence* Moderate
Keys: SD = standard deviation.
Conclusion
Benefits
Compared to placebo ointment, indigo naturalis ointment is significantly more effective in improving the symptoms of scaling, erythema and induration. It also promotes the clearing of psoriasis better among patients with chronic plaque psoriasis. For Outcome 1, the overall quality of evidence is low. Further research is likely to have an important impact on our confidence in this estimate of effect. For Outcome 2, the overall quality of evidence is moderate. Further research is fairly likely to have an important impact on our confidence in this estimate of effect.
Harms
No serious adverse events were reported. 4 patients reported itching after applying the indigo naturalis ointment, at the beginning of the treatment.
Link to Original Article
https://www.ncbi.nlm.nih.gov/pubmed/19015420
The synopsis is based on the following article:
Lin YK, Chang CJ, Chang YC, Wong WR, Chang SC, Pang JH. Clinical assessment of patients with recalcitrant psoriasis in a randomized, observer-blind, vehicle-controlled trial using indigo naturalis. Archives of Dermatology. 2008 Nov;144(11):1457-64


* Interpretation of quality assessment results:
• Very low: Further research is most likely to have an important impact on our confidence in this estimate of effect.
• Low: Further research is likely to have an important impact on our confidence in this estimate of effect.
• Moderate: Further research is fairly likely to have an important impact on our confidence in this estimate of effect.
• High: Further research is unlikely to have an important impact on our confidence in this estimate of effect.
• Very high: Further research is most unlikely to have an important impact on our confidence in this estimate of effect.

Details of assessment method can be found at Chung VC, Wu XY, Ziea ET, Ng BF, Wong SY, Wu JC. Assessing internal validity of clinical evidence on effectiveness of CHinese and integrative medicine: Proposed framework for a CHinese and Integrative Medicine Evidence RAting System (CHIMERAS). European Journal of Integrative Medicine. 2015 Aug 31;7(4):332-41.