Oral herbal medicine for treatment of postherpetic neuralgia: A systematic review and meta-analysis

Abstract Title: Oral herbal medicine for treatment of postherpetic neuralgia: A systematic review and meta-analysis

Background: Postherpetic neuralgia (PHN) is the most common complication of shingles. Herbal medicines for PHN are clinically used to improve chronic pain and other symptoms that reduce quality of life (QoL), such as sleep disturbances and emotional problems.

Purpose/Objectives: This study aims to evaluate the effect and safety of oral herbal medicine for PHN.

Method: Randomized controlled trials(RCTs) for patients diagnosed with PHN and suffered from sustained pain for 3 months or more after were included in this review. Electronic databases, such as PUBMED, EMBASE, Cochrane library, CINAHL (English DB), CNKI, Wanfang (Chinese DB), KoreaMed, RISS, KISS, DBpia, OASIS, and KCI (Korean DB) were searched without language limitation from their inception to September 2022. The intervention group included patients who have received any type of oral herbal medicine for PHN. The control group included individuals with no treatment, placebo treatment, western treatment such as pharmacotherapy and surgical procedure when the intervention group takes oral herbal medicine alone. If the intervention group takes another treatment in addition to oral herbal medicine. The primary outcome is the pain severity of PHN in each study. Quality assessment was performed using the Cochrane risk of bias tool. A meta-analysis was performed to pool the estimated effect.

Results: Nine RCTs involving 767 participants were included with low to moderate quality based on risk of bias assessment. Oral herbal medicine an add-on intervention to western medicine improved visual analogue scale (VAS) pain score (MD -1.46 cm [-1.95 to -0.96], =95%), patients’ Global Impression of change (PGIC) (RR=1.30, [ 1.16 to 1.47] =50%), quality of life(QoL) score (MD = -3.81 points [ -5.11 to -2.51], =93%), and sleep disorder score (MD -1.80 points [-2.30 to -1.31], =50%) compared with western medicine alone. Significant changes from baseline were seen for all groups. No severe adverse events were reported.

Conclusions: Evidence from this review showed that oral herbal medicine alone or as add-on therapy to western medicine was more effective in reducing pain than western medicine alone, and it is safe. In addition, oral herbal medicine plus western medicine can also improve the PGIC, QoL, and sleep disorder. However, considering the low evidence-based qualities of the included RCTs, well designed RCTs with large-scale, and a low risk of bias are needed.

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