TY - JOUR
T1 - Use of medical care biases associations between Parkinson disease and other medical conditions
AU - Gross, Anat
AU - Racette, Brad A.
AU - Camacho-Soto, Alejandra
AU - Dube, Umber
AU - Nielsen, Susan Searles
N1 - Funding Information:
A. Gross reports no disclosures relevant to the manuscript. B. Racette reports research support from Teva (principal investigator [PI]), US WorldMeds (PI), Allergan (PI), and Vaccinex (PI); government research support from NIH (K24ES017765 [PI], R21ES17504 [PI], R01ES021488 [PI], R01ES021488-02S1 [PI], R01ES025991 [PI]); research support from the Michael J. Fox Foundation; and consultation income from 86 Pillars for legal consultation. A. Camacho-Soto reports government research support from NIH (K12HD00109719 [PI]). U. Dube reports no disclosures relevant to the manuscript. S. Searles Nielsen reports government research support from NIH (R21ES17504 [coinvestigator, co-I], R01ES021488 [co-I], R01ES021488-02S1 [co-I], R01ES025991 [co-I], R01ES026891 [co-I]) and research support from the Michael J. Fox Foundation. Go to Neurology.org/N for full disclosures.
Funding Information:
This study was funded by the Michael J. Fox Foundation, the NIH, and the American PD Association. Dr. Racette reports receiving funding from various pharmaceutical companies and consultation income from 86 Pillars. Go to Neurology.org/N for full disclosures.
Publisher Copyright:
© 2018 American Academy of Neurology.
PY - 2018/6/12
Y1 - 2018/6/12
N2 - Objective To examine how use of medical care biases the well-established associations between Parkinson disease (PD) and smoking, smoking-related cancers, and selected positively associated comorbidities. Methods We conducted a population-based, case-control study of 89,790 incident PD cases and 118,095 randomly selected controls, all Medicare beneficiaries aged 66 to 90 years. We ascertained PD and other medical conditions using ICD-9-CM codes from comprehensive claims data for the 5 years before PD diagnosis/reference. We used logistic regression to estimate age-, sex-, and race-adjusted odds ratios (ORs) between PD and each other medical condition of interest. We then examined the effect of also adjusting for selected geographic-or individual-level indicators of use of care. Results Models without adjustment for use of care and those that adjusted for geographic-level indicators produced similar ORs. However, adjustment for individual-level indicators consistently decreased ORs: Relative to ORs without adjustment for use of care, all ORs were between 8% and 58% lower, depending on the medical condition and the individual-level indicator of use of care added to the model. ORs decreased regardless of whether the established association is known to be positive or inverse. Most notably, smoking and smoking-related cancers were positively associated with PD without adjustment for use of care, but appropriately became inversely associated with PD with adjustment for use of care. Conclusion Use of care should be considered when evaluating associations between PD and other medical conditions to ensure that positive associations are not attributable to bias and that inverse associations are not masked.
AB - Objective To examine how use of medical care biases the well-established associations between Parkinson disease (PD) and smoking, smoking-related cancers, and selected positively associated comorbidities. Methods We conducted a population-based, case-control study of 89,790 incident PD cases and 118,095 randomly selected controls, all Medicare beneficiaries aged 66 to 90 years. We ascertained PD and other medical conditions using ICD-9-CM codes from comprehensive claims data for the 5 years before PD diagnosis/reference. We used logistic regression to estimate age-, sex-, and race-adjusted odds ratios (ORs) between PD and each other medical condition of interest. We then examined the effect of also adjusting for selected geographic-or individual-level indicators of use of care. Results Models without adjustment for use of care and those that adjusted for geographic-level indicators produced similar ORs. However, adjustment for individual-level indicators consistently decreased ORs: Relative to ORs without adjustment for use of care, all ORs were between 8% and 58% lower, depending on the medical condition and the individual-level indicator of use of care added to the model. ORs decreased regardless of whether the established association is known to be positive or inverse. Most notably, smoking and smoking-related cancers were positively associated with PD without adjustment for use of care, but appropriately became inversely associated with PD with adjustment for use of care. Conclusion Use of care should be considered when evaluating associations between PD and other medical conditions to ensure that positive associations are not attributable to bias and that inverse associations are not masked.
UR - http://www.scopus.com/inward/record.url?scp=85053890897&partnerID=8YFLogxK
U2 - 10.1212/WNL.0000000000005678
DO - 10.1212/WNL.0000000000005678
M3 - Article
C2 - 29743207
AN - SCOPUS:85053890897
SN - 0028-3878
VL - 90
SP - e2146-e2154
JO - Neurology
JF - Neurology
IS - 24
ER -