Relationship between patient copayments in Medicare Part D and vaccination claim status for herpes zoster and tetanus-diphtheria-acellular pertussis

Objective: To assess the relationship between copay amount and vaccination claim submission status for tetanus-diphtheria-acellular pertussis (Tdap) and herpes zoster (GSK study identifier: HO-14-14319).

Methods: Retrospective analyses were performed using vaccination administrative claims data in patients aged ≥65 years with ≥1 claim for Tdap or zoster vaccines between 2012 and 2014. To avoid confounding by other financial responsibility, analyses were conducted among patients in the copayment phase of insurance. The impact of patient copay amount on vaccination claim status ("canceled" vs. "paid") was evaluated by logistic regression separately for Tdap and zoster, adjusting for patient and provider characteristics.

Results: A total of 81,027 (39.2% with canceled claims) and 346,417 patients (56.8% with canceled claims) were included in the Tdap and zoster analyses, respectively. Mean (standard deviation) copay for canceled vs. paid claims was $37.2 (18.4) vs. $31.1 (20.1) for Tdap and $64.9 (36.9) vs. $53.5 (38.8) for zoster. The adjusted odds ratios (ORs) for a canceled Tdap vaccine claim, compared with $0 copay, were 1.19 ($1-25 copay), 1.76 ($26-50 copay), 2.42 ($51-75 copay) and 2.40 ($76-100 copay), all p < .001. The adjusted ORs for a canceled zoster vaccine claim, compared with $0 copay, were 1.02 ($1-25), 1.39 ($26-50), 1.66 ($51-75), 2.07 ($76-100) and 2.71 (>$100), all p < .001 except for $1-25 (p = .172).

Conclusions: High patient copay is a barrier to Tdap and zoster vaccinations in Medicare Part D patients. Providing vaccines at low or no copay may improve vaccination rates in these adults. GSK study identifier: HO-14-14319.