Using linked administrative and census data for migration research.

Migration is a core component of population change and is both a symptom and a cause of major economic and social phenomena. However, data limitations mean that gaps remain in our understanding of the patterns and processes of mobility. This is particularly the case for internal migration, which remains under-researched, despite being quantitatively much more significant than international migration. Using the Scottish Longitudinal Study, this paper evaluates the potential value of General Practitioner administrative health data from the National Health Service that can be linked into census-based longitudinal studies for advancing migration research. Issues relating to data quality are considered and, using the illustrative example of internal migration by country of birth, an argument is developed contending that such approaches can offer novel ways of comprehending internal migration, by shedding additional light on the nature of both movers and the moves that they make.

Risk factors for sporadic Creutzfeldt-Jakob disease.

OBJECTIVE: Although surgical transmission of Creutzfeldt-Jakob disease (CJD) has been demonstrated, these iatrogenic cases account for only a small proportion of all CJD cases. The majority are sporadic CJD (sCJD) cases of unknown cause. This study investigated whether some cases classified as sCJD might have an unrecognized iatrogenic basis through surgical or other medical procedures METHODS: This study compared medical risk factors from 431 sCJD cases referred 1998 to 2006 with 454 population control subjects. Possible geographic and temporal links between neurological and gynecological operations in 857 sCJD cases referred from 1990 to 2006 were investigated RESULTS: A reported history of ever having undergone surgery was associated with increased risk for sCJD (odds ratio, 2.0; 95% confidence interval, 1.3-2.1; p = 0.003). Increased risk was not associated with surgical categories chosen a priori but was confined to the residual category "other surgery," in which the increase in risk appeared most marked for three subcategories: skin stitches, nose/throat operations, and removal of growths/cysts/moles. No convincing evidence was found of links (same hospital, within 2 years) between cases undergoing neurosurgery or gynecological surgery INTERPRETATION: It is unlikely that a high proportion of UK sCJD cases are the result of transmission during surgery, but we cannot exclude the possibility that such transmission occurs occasionally. A study based on accurate surgical histories obtained from medical records is required to determine whether the increased risk associated with reported surgical history reflects a causal association or recall bias.

Risk factors for variant Creutzfeldt-Jakob disease: a case-control study.

OBJECTIVE: To investigate the potential risk factors for variant Creutzfeldt-Jakob disease (VCJD) in the United Kingdom. METHODS: Definite and probable vCJD cases (n = 136) were residing in Great Britain at disease onset, and were referred between May 1995 and November 2003. Control subjects (n = 922) were recruited between 2002 and 2003, from 100 randomly selected geographical clusters sampled to represent the geographical distribution of vCJD. RESULTS: Reported frequent consumption of beef and beef products thought likely to contain mechanically recovered or head meat, or both, including burgers and meat pies, was associated with increased risk for vCJD, as was reported frequent chicken consumption. Surgical operations were generally similarly reported for cases and control subjects, with the exception of a small group of minor operations, possibly attributable to underreporting in control subjects. Cases and control subjects had similar reported occupational histories and exposure to animals. INTERPRETATION: These findings are consistent with dietary exposure to contaminated beef products being the main route of infection of vCJD, but recall bias cannot be excluded. There was no convincing evidence of increased risk through medical, surgical, or occupational exposure or exposure to animals.

The geographical distribution of variant Creutzfeldt-Jakob disease cases in the UK: what can we learn from it?

The causative agents of variant Creutzfeldt-Jakob disease (vCJD) and of bovine spongiform encephalopathy (BSE) are currently indistinguishable. However, the route(s) by which humans became infected remain unknown. The path by which humans were infected with the BSE agent might impact on the geographical distribution of cases and we therefore sought evidence of regional variation and local clustering of vCJD cases. With the notable exception of a group of five cases in Leicestershire, the absence of local clustering of vCJD cases is compatible with most human exposure to the vCJD agent arising through routes that result in the risk of infection being similar over wide geographical areas, rather than through small-scale local events. Infection through the consumption of mechanically recovered meat (MRM) contaminated with the BSE agent was a potential route for such widespread exposure. An ecological analysis relating the regional incidence of vCJD to historical dietary data does not provide a dear evidence that humans became infected through consumption of MRM.

PRNP contains both intronic and upstream regulatory regions that may influence susceptibility to Creutzfeldt-Jakob Disease.

The Prion protein (PrP) plays a central role in Creutzfeldt-Jakob Disease (CJD) and other transmissible spongiform encephalopathies (TSEs). Mutations in the protein coding region of the human PrP gene (PRNP), which have been proposed to alter the stability of the PrP protein, have been linked to a number of forms of TSE. However, the majority of CJD cases are not associated with mutations in the PRNP coding region and alternative mechanisms must therefore underlie susceptibility to these forms of CJD. Transgenic mice, that over- or under-express PrP genes, have shown a correlation between the level of PrP gene expression and the incubation time of disease. Polymorphisms that lead to alterations in human PRNP gene expression, could therefore be candidates for influencing susceptibility of an individual to CJD. In order to investigate this hypothesis, we have defined an upstream and intronic regulatory region of the PRNP gene. Sequencing of these regions in controls, sporadic CJD (sCJD) and variant CJD (vCJD) patients has identified three polymorphisms, all of which are more common in sCJD patients than controls. Our data suggests that polymorphisms in the regulatory region of the PRNP gene may be a risk factor for CJD.