http://www.parkinsons.org.uk/pdf/Par...evalenceUK.pdf
since most people who have pd will get medical care, this seems to be a relevant database since they will be in the database, it only counts pd'ers and there is likely very little
duplication. not sure if anyone has studied it for epidemiology.

the prescription database you used imho isn't very useful for epidemiology with the simple caveat that a lot of the dopamine agonists are used for restless leg syndrome and essential tremor. plus with pd, patients often seek out specialists far away or if they move away will continue to have their rx's written by the same doctor even years into the future since you don't always have to go in for a yearly exam if nothing has really changed. you really also have to study the british health care system to figure out their RX filling system to draw any conclusions even about prescribing habits. one doctor moving into or out of an area could make a big difference plus the introduction of a new drug, some doctors might embrace it more quickly than others. my point is statistics don't mean much unless you understand the system you are sampling.