Polymyalgia rheumatica following infective triggers or vaccinations: a different subset of disease?

Polymyalgia rheumatica (PMR) is the commonest inflammatory disorder of the elderly; an association with environmental triggers and a deregulated immune response have been described. The aim of this study was to investigate the association of environmental triggers before the onset of PMR.

The database of 58 consecutive PMR patients recruited from a single rheumatology secondary care setting was retrospectively analyzed to investigate the frequency of environmental triggers and correlations with clinical characteristics, ultrasound and laboratory data.

Fifteen PMR patients (26%) described a connection with environmental agents: six PMR patients reported a vaccination, 4 reported a respiratory tract infection, 5 reported seasonal influenza before the onset of the disease. The model of multivariate linear regression which better predicted a shorter time to normalize inflammatory reactants (R ² = 27.46%, p = 0.0042) comprised the presence of an environmental trigger and a higher PCR. A linear regression analysis confirmed an inverse correlation between PCR at onset and time to normalize inflammatory reactant (r = -0.3031, p = 0.0208). A significant correlation was demonstrated between presence of environmental trigger and shorter time to normalize inflammation (r = -0.5215, p< 0.0001), and lesser frequency of gleno-humeral synovitis on US (r = -0.3774, p = 0.0038).

Our work describes a correlation between environmental triggers in PMR and higher CRP at diagnosis, faster response to therapy, and milder shoulder synovitis. We may suppose that these patients belong to a more specific subtype of PMR, in whom external stimuli, such as vaccination or infection, may lead to a deregulated response within the context of an impaired senescent immuno-endocrine system.