title: Giardiasis in North West England: faecal specimen requesting rates by GP practice.
abstract: Many cases of giardiasis in the UK are undiagnosed and among other things, diagnosis is dependent upon the readiness of GPs to request a specimen. The aim of this study is to assess the rate of specimens requested per GP practice in Central Lancashire, to examine the differences between GP practices and to estimate the pattern of unexplained spatial variation in the practice rate of specimens after adjustment for deprivation. To achieve this, we fitted a set of binomial and Poisson regression models, with random effects for GP practice. Our analysis suggests that there were differences in the rate of specimens by GP practices (P < 0·001) for a single year, but no difference in the proportion of positive tests per specimen submitted or in the rate of positive specimens per practice population. There was a difference in the cumulative rate of positive specimens per practice population over a 9-year period (P < 0·001). Neither the specimen rate per practice for a single year nor the cumulative rate of positive specimens over multiple years demonstrated significant spatial correlation. Hence, spatial variation in the incidence of giardiasis is unlikely to be confounded by variation in GP rate of specimens.
authors.affiliation: CHICAS,Lancaster Medical School,Lancaster University,Lancaster,UK.
authors.forename: N F
authors.initials: NF
authors.lastname: Reeve
authors.affiliation: Department of Primary Care Health Sciences,Oxford University,Oxford,UK.
authors.forename: T R
authors.initials: TR
authors.lastname: Fanshawe
authors.affiliation: Cumbria and Lancashire Public Health England Centre,Chorley,UK.
authors.forename: K
authors.initials: K
authors.lastname: Lamden
authors.affiliation: CHICAS,Lancaster Medical School,Lancaster University,Lancaster,UK.
authors.forename: P J
authors.initials: PJ
authors.lastname: Diggle
authors.affiliation: Royal Preston Hospital,Sharoe Green Lane,Preston,UK.
authors.forename: J
authors.initials: J
authors.lastname: Cheesbrough
authors.affiliation: CHICAS,Lancaster Medical School,Lancaster University,Lancaster,UK.
authors.forename: T J
authors.initials: TJ
authors.lastname: Keegan
mesh_terms: D004739:England / Q000453:epidemiology; D005243:Feces / Q000469:parasitology*; D058006:General Practice / Q000706:statistics & numerical data*; D005873:Giardiasis / Q000175:diagnosis* / Q000453:epidemiology; D006801:Humans; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D012044:Regression Analysis; D012959:Socioeconomic Factors; D013048:Specimen Handling / Q000706:statistics & numerical data*
keywords: water-borne infections