Appendectomy and risk of Parkinson's disease: A nationwide cohort study with more than 10 years of follow-up.
The appendix may be a key site for the initiation of Parkinson's disease (PD) pathology. We examined the hypothesis that appendectomy is associated with lower PD risk.



We used Danish medical and administrative registries to construct a cohort of all patients in Denmark with an operation code of appendectomy during 1980-2010 (n = 265,758) and a matched general population comparison cohort (n = 1,328,790). Using Cox regression, we computed hazard ratios and corresponding 95% confidence intervals for PD, adjusting for potential confounders and stratifying on age at appendectomy (≤45 years / > 45 years), sex, and follow-up time.



During follow-up ( > 10 years), PD incidence was 0.19 and 0.15 per 1,000 person-years at risk in the appendectomy cohort and in the general population comparison cohort, respectively, yielding a slightly increased risk of PD (adjusted hazard ratio = 1.14; 95% confidence interval 1.03-1.27). Findings were consistent after more than 20 years of follow-up and when stratified on age of appendectomy and sex.



Appendectomy was associated with a small increase in PD risk 10 or more years after surgery. © 2016 International Parkinson and Movement Disorder Society.
Department of Clinical Epidemiology, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.
Elisabeth
0000-0001-6706-6336
E
Svensson
Department of Clinical Epidemiology, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.
Erzsébet
E
Horváth-Puhó
Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark.
Morten Gersel
MG
Stokholm
Department of Clinical Epidemiology, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.|Department of Health Research & Policy (Epidemiology) and Clinical Excellence Research Center, Stanford University, Stanford, California, USA.
Henrik Toft
HT
Sørensen
Department of Clinical Epidemiology, Institute of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark.|Department of Health Research & Policy (Epidemiology), Stanford University, Stanford, California, USA.|Department of Neurology & Neurological Sciences, Stanford University, Stanford, California, USA.
Victor W
VW
Henderson
Department of Nuclear Medicine & PET Centre, Aarhus University Hospital, Aarhus, Denmark.
Per
P
Borghammer
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001062:Appendectomy / Q000706:statistics & numerical data*; D002648:Child; D002675:Child, Preschool; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000453:epidemiology*; D012042:Registries / Q000706:statistics & numerical data*; D012306:Risk; D055815:Young Adult
Parkinson's disease; appendectomy; risk factor