ARIZONA study: is the risk of post-herpetic neuralgia and its burden increased in the most elderly patients?

BACKGROUND: In a context of change in the demographic profile of the older population, to identify an age threshold for increased risk and burden of herpes zoster (HZ) in 70+ patients. METHODS: Post hoc analysis of the 12-month French nationwide prospective observational ARIZONA cohort study. HZ was assessed by means of the following validated questionnaires: Neuropathic Pain Symptom Inventory (NPSI), Zoster Brief Pain Inventory (ZBPI), Short-Form health survey (SF-12), and Hospital Anxiety and Depression Scale (HADS). RESULTS: 644 general practitioners included 1,358 volunteer patients with acute HZ in the ARIZONA study; 609 patients (45%) were 70+. In 70+ patients, age did not increase rash severity or HZ-related pain intensity at diagnosis, but increased by 64% the frequency of ophthalmic zoster (from 5.5% in 70–74 years age-group to 9.0% in 85+ patients, p = NS). Age was significantly associated with low physical health as assessed by the SF-12 Physical Component Summary (SF-12 PCS) score and bad mood as assessed by the HADS depression score (p < 0.001). Within the year following HZ, post-herpetic neuralgia (PHN) was systematically but not significantly more frequent in 85+ patients than in the 70–74, 75–79, or 80–84 years age-groups (19.0% vs. 13.3%/15.3%/11.6% at month 3; 15.1% vs. 7.3%/11.0%/12.2% at month 6; 15.2% vs. 6.0%/8.0%/6.0% at month12, respectively). SF-12 PCS and HADS depression scores improved from day 0 to month 12 in all patients (p < 0.001). 85+ patients were more impaired than younger patients (p < 0.001), but without clear difference according to PHN. CONCLUSIONS: This study did not show in 70+ patients a clear and significant age threshold at which disease burden increased, although for some domains the impact seemed higher among the oldest patients; the cut-off of 70 years remains thus relevant for clinical and epidemiological studies. However, at individual level, assessment of the burden of HZ and HZ-related pain appears necessary to improve management and prevent functional decline in the most vulnerable 70+ patients. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1471-2334-14-529) contains supplementary material, which is available to authorized users.