I calculated incidence rates (IR) for colorectal cancer using an age-period-cohort model. Is it useful for GPs to use such age, gender and anatomical sub-site specific IRs as a baseline risk, during the assessment of cancer risk in patients who present with lower abdominal symptoms? My concern is that CRC risk is different in the general population and in the primary care population.
Hello and welcome to SE Medical Sciences. I'd recommend not over using acronyms, (you forgot to define 'CRC' as Colorectal Cancer.). It is difficult to know what you mean you mean by 'general population' & 'primary care', regardless could I get some clarification?
As Rodrigo de Azevedo rightfully pointed out, this is not quite an epidemiological question.
Epidemiology - The incidence, distribution, and possible control of diseases and other factors relating to health.
Epidemiology of cancer - Seeks to identify the cause of cancer.
Primary health care - Is generally the first contact a person has with the health care system and therefore present with symptoms.
General population - People that make-up the population of a city, state or country.
If a study uses a representative sample from a population, check their method to see where their statement on 'how' or 'why' they chose that exact sample. It should sate if it is from private practice, the general population or specialist clinic.
"A randomly-selected cohort in the general population recruited by telephone, and patients recruited in the waiting room of 12 primary care clinics"