A Study of Risk Factors in Postherpetic Neuralgia

Abstract

A Study of Risk Factors in Postherpetic Neuralgia

Kanchana          Sermswan          MD

Department of Medicine, BMA Medical College and Vajira Hospital

Objective: To determine general risk factors in postherpetic neuralgia.

Study design: Retrospective descriptive study.

Subjects: During one year period between January and December of 2001, 208 patients who were diagnosed herpes zoster attended as out patient of dermatological clinic were reviewed.

Methods: All medical records of patients who were diagnosed as herpes zoster and attended at least one month period were reviewed. Epidemiological data, immunological starts, anitviral prescription and PHN were assessed. All suspected risk factors and PHN were compared using Chi-square test.

Main outcome measures: Risk factors (age, sex, site of lesions, immunocompromised patients and antiviral therapy) of postherpetic neuralgia and efficacy of antiviral therapy in decreasing postherpetic neuralgia.

Results: Prevalence of herpes zoster was highest in 31-40 years. Prevalence of PHN was 37 cases (17.79%), highest in 61-70 years (48.28%). Eight cases (21.05%) of PHN found in systemic immune-compromised patients compared with 17.06% in normal immunity persons (p =0.561). Odd ratio of PHN in facial zoster found 1.32 to zoster in trunk (p=0.493). Odd ratio of antiviral therapy was 0.43 to non-antiviral therapy groups (p = 0.017). Patients older than 50 years had odd ratio of 0.40 to younger patients (p = 0.023).Female with antiviral therapy had PHN odd ratio for 0.31 to female not treated with antivirus (p = 0.011). Younger age group, 21-50 years, treated with antivirus had odd ratio 0.51 to untreated group (p = 0.286)

Conclusion: All 208 medical records of herpes zoster were reviewed. Prevalence of herpes zoster was highest in 31-40 years, PHN was hightest in 61-70 years. Antiviral therapy decreased PHN significantly in all age groups with better benefit in patients over 50 years, female. Immunocompromised patients, facial zoster and younger patients had tendency to benefit from antiviral therapy.

Key words: herpes zoster, postherpetic neuralgia, antiviral therapy.

Vajira Med J 2002 ; 46 : 205 - 212