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A seasonal pattern in the onset of polymyalgia rheumatica
M A Cimmino1, R Caporali, C M Montecucco
1Department of Rheumatology, Genoa University, Italy.
Abstract:
The seasonal distribution in the onset of polymyalgia rheumatica (PMR) was determined in 58 patients with the disease and compared with that in 44 patients affected by rheumatoid arthritis of elderly onset (EORA). Thirty six (62%) cases of PMR developed during May to August; by contrast, only 14 (31%) cases of EORA developed in the same months, this latter disease failing to show any seasonal clustering. The monthly distribution of PMR correlated with outside temperature and hours of sunshine. These data suggest that PMR might be triggered by such factors as actinic damage of superficial vessels or infective agents with a seasonal cycle. Finally, the summer clustering of PMR may be helpful in the differential diagnosis from EORA.
Insights
Polymyalgia rheumatica (PMR) shows a distinct summer onset, unlike elderly onset rheumatoid arthritis (EORA). This seasonal pattern may be linked to environmental factors like temperature and sunshine, aiding in differential diagnosis.
Area of Science:
- Rheumatology
- Epidemiology
- Environmental Medicine
Background:
- Polymyalgia rheumatica (PMR) is an inflammatory condition primarily affecting individuals over 50.
- Understanding the environmental triggers and seasonal patterns of PMR is crucial for diagnosis and management.
- Elderly onset rheumatoid arthritis (EORA) serves as a comparative condition to identify PMR-specific characteristics.
Purpose of the Study:
- To investigate the seasonal distribution of PMR onset.
- To compare the seasonal patterns of PMR with EORA.
- To explore potential environmental factors influencing PMR incidence.
Main Methods:
- Retrospective analysis of patient data.
- Comparison of onset dates for PMR and EORA cases.
- Correlation analysis with meteorological data (temperature, sunshine hours).
Main Results:
- A significant seasonal clustering of PMR onset was observed during May to August (62% of cases).
- In contrast, EORA showed no significant seasonal clustering (31% of cases in the same period).
- PMR onset distribution correlated positively with outside temperature and sunshine hours.
Conclusions:
- PMR exhibits a clear seasonal predilection for summer onset.
- Environmental factors, potentially including actinic damage or seasonal infections, may trigger PMR.
- The summer clustering of PMR is a valuable feature for differentiating it from EORA.