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PubMed2004

Ecological measures of socioeconomic status and hospital readmissions for asthma among Canadian adults.

BACKGROUND: Lack of an association between area-based socioeconomic status (SES) and readmission for asthma was investigated in a country with a universal health care system. METHODS: Data linkage analysis was conducted based on hospitalization data from Statistics Canada's Person-oriented Information Database and area-based SES data from the 1996 Census. Hospital records for 8333 asthma patients aged 20-64 years in all Canadian provinces except Quebec who were admitted in 1995/1996 were linked to determine the number of patients who were rehospitalized within the same fiscal year. The area-based SES of the patients was defined according to the average personal income and proportion of residents with a university degree in an enumeration area (EA). Incidence rates of readmission for asthma were calculated based on the total years at risk. Cox's proportional hazard model was used to adjust for age, sex, province, and length of stay for first admission. RESULTS: The incidence rate of asthma rehospitalization was 31.6 per 100 person-years for men and 37.2 per 100 person-years for women. Neither average EA income or education level was significantly associated with rehospitalization for asthma. Women living in poor areas tended to have an increased incidence of asthma rehospitalization, but the difference was not significant after adjustment for covariates using the Cox regression model. CONCLUSION: Socioeconomic status measured at the neighborhood level has no significant impact on rehospitalization for asthma among Canadian adults.

Adult↗
PubMed2006

A survey of data mining methods for linkage disequilibrium mapping.

Data mining methods are gaining more interest as potential tools in mapping and identification of complex disease loci. The methods are well suited to large numbers of genetic marker loci produced by high-throughput laboratory analyses, but also might be useful for clarifying the phenotype definitions prior to more traditional mapping analyses. Here, the current data mining-based methods for linkage disequilibrium mapping and phenotype analyses are reviewed.

Chromosome Mapping↗
PubMed1999

No evidence of linkage disequilibrium between a CAG repeat in the SCA1 gene and schizophrenia in Caucasian and Chinese schizophrenic subjects.

Several recent studies have reported evidence for a schizophrenia locus on chromosome 6p, with a variety of linked markers spanning a approximately 40 cM region between D6S470 and D6S291. However because of the wide region implicated and the difficulty of inferring phenotype from genotype in complex disorders, it is difficult to define its location precisely using linkage data. An alternative approach is to search for linkage disequilibrium. On chromosome 6p, allelic association with a (CAG)29 allele of a triplet repeat marker in the SCA1 gene has been reported, and we have attempted to replicate this finding using a Caucasian case-control sample of 211 affected subjects and 204 controls, and a Han Chinese sample of 100 affected family trios. In the case-control sample, the frequency of the (CAG)29 allele was similar in cases and controls (35%), and no other alleles provided evidence for allelic association. Likewise, there was no evidence for preferential transmission of the (CAG)29 allele to affected offspring in the Chinese sample, although a different allele, (CAG)26, was more often transmitted to the affected offspring. However this data did not reach statistical significance (P = 0.1). We conclude that our data does not support the notion that there is a locus for schizophrenia close to the SCA1 gene. However, since linkage disequilibrium will vary between distinct populations, we cannot exclude this possibility.

Asian People↗
PubMed1997

The potential of using billing data for emergency department injury surveillance.

OBJECTIVE: To determine the availability of and sample statewide ED injury information obtained from hospital billing data for the purpose of demonstrating the feasibility of information acquisition for subsequent data linkage. METHODS: A retrospective, database investigation was conducted to obtain data describing a statewide stratified sample of ED patients. The aim was to collect a computerized billing summary record for each injured ED patient seen at each sampled hospital over a 1-year period. All 215 Pennsylvania acute care hospitals in 1991 were eligible for sample selection. Data collection for the project was conducted in 1993. Participants included directors of hospital medical records and billing departments. RESULTS: Twenty-four hospitals contributed data sets from the original target goal of 31 strata. The final combined data set contained 187,404 records with injury diagnoses from approximately 616,000 ED patient visits, representing a 12% sample of all annual statewide ED visits. Age, sex, date of visit, and primary diagnosis fields were completed from the retrieved data > 99% of the time. More than two-thirds of the sampled records had a social security number, and total charges were recorded > 90% of the time. Other variables such as name and address were contained in < 50% of the records submitted. E-codes were usually not available. CONCLUSIONS: Retrospective compilation of multihospital ED billing data to create a statewide ED data sample-with the potential for injury research and probabilistic database linkage-can be accomplished; there are, however, important limitations.

Data Collection↗
PubMed2006

Modelling changes in the determinants of PHI utilisation in Western Australia across five health care policy eras between 1981 and 2001.

OBJECTIVE: In this study of the Western Australian population we analysed changes in the demographic determinants of PHI use across health policy eras. Specifically, we aimed to predict the probability that an individual, defined by a pre-determined set of characteristics, would utilise PHI for in-patient hospitalisation in WA in each of five health policy eras spanning 1981-2001. METHODS: The WA Data Linkage System was used to extract hospital morbidity data from 1 January 1981 to 31 December 2001. Random effects logistic regression analysis was used to estimate the likelihood of utilising private health insurance in each of five health policy eras based on the timing and composition of changes in federal health care policy. RESULTS: The use of PHI for in-patient hospitalisation fell significantly from 1981 to 1997 (61% above to 53% below the odds of being a public patient). From 1999, however, the odds of using PHI substantially increased to 16% above that of being a public patient. The likelihood of using PHI in all age fell approximately exponentially across successive health policy eras compared with that in the oldest (70+ years) age group. From 1997 onwards, the relative probabilities of average and disadvantaged individuals using PHI substantially increased compared with extremely advantaged individuals. CONCLUSION: Our study found that the overall likelihood of utilising PHI versus utilising Medicare for in-patient hospitalisation, adjusted for all demographic characteristics, decreased between 1981 and 1998 but increased precipitously after 1999. We also found that the determinants of using PHI have changed significantly across health policy eras. The most significant changes occurred with respect to age (the probability of PHI use by older individuals increased) and socio-economic status (the probability of PHI use by average and disadvantaged individuals increased). This shift in the effects of determinants of PHI suggests that the introduction of the recent health policies were associated with a change in both the age and socio-economic profile of individuals who utilise PHI.

Adolescent↗
PubMed2005

Confidentiality and spatially explicit data: concerns and challenges.

Recent theoretical, methodological, and technological advances in the spatial sciences create an opportunity for social scientists to address questions about the reciprocal relationship between context (spatial organization, environment, etc.) and individual behavior. This emerging research community has yet to adequately address the new threats to the confidentiality of respondent data in spatially explicit social survey or census data files, however. This paper presents four sometimes conflicting principles for the conduct of ethical and high-quality science using such data: protection of confidentiality, the social-spatial linkage, data sharing, and data preservation. The conflict among these four principles is particularly evident in the display of spatially explicit data through maps combined with the sharing of tabular data files. This paper reviews these two research activities and shows how current practices favor one of the principles over the others and do not satisfactorily resolve the conflict among them. Maps are indispensable for the display of results but also reveal information on the location of respondents and sampling clusters that can then be used in combination with shared data files to identify respondents. The current practice of sharing modified or incomplete data sets or using data enclaves is not ideal for either the advancement of science or the protection of confidentiality. Further basic research and open debate are needed to advance both understanding of and solutions to this dilemma.

Confidentiality↗
PubMed2003

A method for evaluating the results of Bayesian model selection: application to linkage analyses of attributes determined by two or more genes.

OBJECTIVES: We apply and evaluate the intrinsic Bayes factor (IBF) of Berger and Pericchi [J Am Stat Assoc 1996;91:109-122; Bayesian Statistics, Oxford University Press, vol 5, 1996] to linkage analyses done using the stochastic search variable selection (SSVS) method of George and McCulloch [J Am Stat Assoc 1993;88:881-889] as proposed by Suh et al. [Genet Epidemiol 2001;21(suppl 1):S706-S711]. METHODS: We consider 20 simulations of linkage data obtained under two different generating models. The SSVS is applied to a multiple regression extension [Genet Epidemiol 2001;21(suppl 1): S706-S711] of the Haseman-Elston [Behav Genet 1972;2:3-19; Genet Epidemiol 2000;19:1-17] methods. Four prior distributions are considered. We apply the IBF criterion to those samples where different prior distributions result in different top models. RESULTS: In those samples where three different models were obtained using the four priors, application of the IBFs eliminated one of the two wrong models in 4 out of 5 situations. Further elimination using the IBF criterion for situations with two different subsets did not serve as well. CONCLUSIONS: When different priors result in three or more different subsets of markers, one can use the IBF to get this number down to two for consideration. When two subsets result we recommend that both be considered.

Bayes Theorem↗
PubMed1987

Ten families with fragile X syndrome: linkage relationships with four DNA probes from distal Xq.

We present clinical, cytogenetic, and linkage data of four DNA probes from the terminal long arm of the X chromosome in ten new families with fragile X syndrome. A prior/posterior method of multipoint linkage analysis is employed to combine these results with published data to refine the linkage map of terminal Xq. Ten possible probe/disease orderings were tested. The order with the greatest posterior probability (0.78) of the five loci is 52a-F9-fragile X gene-DX13-St14, although the order with reversal of the positions of 52a and F9 has a posterior probability 0.15. The mean estimates of the distances between the probes and the fragile X gene are 38 cM and 33 cM for the proximal probes 52a and F9, and 8 cM and 12 cM for the distal probes DX13 and St14. Although the current method of choice in the prenatal diagnosis and carrier detection of the fragile X syndrome remains detailed cytogenetic analysis, consideration is given to the potential role of these DNA probes, both singly and in pairs.

Chromosome Banding↗
PubMed2005

Oligogenic inheritance in neuroblastoma.

Neuroblastoma (NB), a childhood malignancy affecting neural crest deriving cell lineages, is characterized by great clinical variability and histological heterogeneity. As NB usually occurs as sporadic form, molecular studies were mainly carried out on tumor samples and derived cell lines, leading to the identification of several somatic alterations. Although familial NB is rare, linkage data obtained from different families have provided evidence of linkage to markers mapping to different chromosomal regions, indicating a remarkable genetic heterogeneity of NB. The first evidence of germline mutations in NB pedigrees has been recently reported in the paired-like homeobox 2B (PHOX2B) gene, involved in the development of neural crest deriving cells. Nevertheless, as only a few NB families but not others have been shown to carry PHOX2B mutations, the role of this gene in NB predisposition has still to be clarified. On the basis of the current data, familial NB cannot be modeled as a Mendelian monogenic trait. Instead, an oligogenic mode of inheritance might explain the existence of different NB loci genetically interacting to cause and/or modify the disease-phenotype.

Female↗
PubMed1987

Linkage and genetic counselling for the fragile X using DNA probes 52A, F9, DX13, and ST14.

Linkage data using the markers DXS51, F9, DXS15, and DXS52 are presented from 14 pedigrees segregating with the fragile X. Cytogenetic and DNA data were combined by two- or three-point linkage analysis for estimation of lod scores and carrier probabilities in potential carriers. Recombination frequencies (theta) corresponding to maximum z scores (zeta) were obtained for DXS51 (zeta = 3.45, theta = 0.0), DXS15 (zeta = 0.40, theta = 0.06), F9 (zeta = 3.15, theta = 0.09), and DXS52 (zeta = 3.60, theta = 0.11) with the fragile X. Considerable alterations to carrier probabilities occurred in some cases, especially when flanking markers were informative. The chance of mentally impaired offspring was reduced to 1% for five of eight women with prior carrier probabilities of 32%. Three pedigrees were identified in which mutation had possibly occurred. An alternative explanation for two of these was inheritance of the fragile X from normal males and for the other inheritance from a clinically normal woman. Probabilities were computed for each of these alternatives.

DNA↗
PubMed1987

MAPMAKER: an interactive computer package for constructing primary genetic linkage maps of experimental and natural populations.

With the advent of RFLPs, genetic linkage maps are now being assembled for a number of organisms including both inbred experimental populations such as maize and outbred natural populations such as humans. Accurate construction of such genetic maps requires multipoint linkage analysis of particular types of pedigrees. We describe here a computer package, called MAPMAKER, designed specifically for this purpose. The program uses an efficient algorithm that allows simultaneous multipoint analysis of any number of loci. MAPMAKER also includes an interactive command language that makes it easy for a geneticist to explore linkage data. MAPMAKER has been applied to the construction of linkage maps in a number of organisms, including the human and several plants, and we outline the mapping strategies that have been used.

Chromosome Mapping↗
PubMed2004

Multiple loci are linked with anti-red blood cell antibody production in NZB mice -- comparison with other phenotypes implies complex modes of action.

The New Zealand Black (NZB) mouse strain is a model of autoimmune haemolytic anaemia (AHA) and systemic lupus erythematosus (SLE), characterized by the production of anti-red blood cell (RBC) antibodies and anti-nuclear antibodies (ANA), respectively. A linkage analysis was carried out in an (NZB x BALB/c) F(2) cross in order to identify loci involved in the production of both anti-RBC IgM and IgG antibodies. These regions of linkage were compared with linkage data to ANA from the same cohort and other linkage analyses involving New Zealand mice. Four previously described NZB loci linked to anti-RBC antibodies were confirmed, and eight novel loci linked to this trait were also mapped: five of which were of NZB origin, and three derived from the non-autoimmune BALB/c background. A comparison between loci linked with anti-RBC antibodies and ANA demonstrated many that co-localize, suggesting the presence of genes that result in the general breaking of tolerance to self-antigen. Furthermore, the observation that some loci were associated only with the anti-RBC response suggests an antigen specific mechanism in addition to a general breaking of tolerance. A locus linked with anti-RBC antibodies and ANA on distal chromosome 7 in this cohort is orthologous to one on the q arm of human chromosome 11, a region linked to AHA and ANA in human SLE.

Anemia, Hemolytic, Autoimmune↗
PubMed1993

Incidence and origin of "null" alleles in the (AC)n microsatellite markers.

Twenty-three (AC)n repeat markers from chromosome 16 were typed in the parents of the 40 CEPH (Centre d'Etude du Polymorphisme Humain) families. Where parents were informative, the entire families were then typed. There were seven markers in which null alleles were demonstrated, as recognized by the apparent noninheritance, by a sib, of a parental allele. Four of these markers showed a null allele in a single sibship, while in the other three at least 30% of the CEPH sibships were shown to have a null allele segregating. One null allele was sequenced and shown to be the result of an 8-bp deletion occurring within the priming sequence for PCR amplification of the (AC)n repeats. In gene mapping or in application to diagnosis, the presence of a segregating null allele will not corrupt the linkage data but could result in loss of information. In isolated instances a segregating null allele may be interpreted as nonpaternity. The presence of a null allele may generate misleading data when individuals are haplotyped to determine the presence of linkage disequilibrium with a disease gene.

Alleles↗
PubMed1991

A multipedigree linkage study of X-linked deafness: linkage to Xq13-q21 and evidence for genetic heterogeneity.

A locus for X-linked nonsyndromic deafness has previously been allocated to the Xq13-q21 region based on linkage studies in two separate pedigrees. This has been substantiated by the observation of deafness as a clinical feature of male patients with cytogenetically detectable deletions across this region. The question of a second locus for deafness in this chromosomal region has been raised by the audiologically distinct nature of the deafness in some of the deleted patients compared to that observed in those patients upon whom the linkage data are based. We have performed detailed clinical evaluation and linkage studies on seven pedigrees with nonsyndromic X-linked deafness and conclude that there is evidence for at least two loci for this form of deafness, including one in the Xq13-q21 region. We have observed different radiological features among the pedigrees which map to Xq13-q21, suggesting that even among these pedigrees the deafness is due to different pathological processes. Given these findings, we suggest that the classification of nonsyndromic X-linked deafness based solely on audiological criteria may need to be reviewed.

Chromosome Mapping↗
PubMed2003

Ovarian cancer in Western Australia (1982-1998): trends in surgical intervention and relative survival.

OBJECTIVES: We aimed to review the utilisation and trends in surgical procedures for the primary management of ovarian cancer and the survival outcomes of patients surgically treated in Western Australia. METHODS: The population-based Western Australia Data Linkage System was used to link hospital morbidity and mortality data for all women diagnosed with malignant primary ovarian cancer in the State Cancer Registry in the period 1982-1998. Poisson regression was used to analyse trends in surgical procedure rates. Logistic regression examined the likelihood of having a surgical procedure in the periods 1988-1993 and 1994-1998 compared with 1982-1987. Relative survival was used to adjust survival estimates for other causes of death occurring in the general female population. RESULTS: There were 1,126 women who underwent a primary surgical procedure for ovarian cancer in Western Australia in the period 1982-1998. Women were more likely to undergo surgery in 1994-1998 (87.8%) compared with 1988-1993 (76.8%), but there was no difference when compared to 1982-1987 (89.2%) (P = 0.62). The likelihood of using specific surgical procedures to treat ovarian cancer increased for all but total abdominal hysterectomy. Bilateral salpingo-oophorectomy was 3.7 times more likely to be performed and omentectomy 5 times more likely to be performed in 1994-1998 compared with 1982-1987. The median length of hospital stay decreased from 15 to 12 days and emergency admissions decreased from 26.5 to 15.4% over the three time periods. Thirty-two percent of women were readmitted within 30 days of separation from their primary surgery, 23% of which were for the same-day treatment with either chemotherapy or radiotherapy. A 15% increase in relative survival was observed between the periods 1982-1997 (38.8%) and 1994-1998 (53.5%).Conclusion. CONCLUSION: Surgery remains a cornerstone in the primary management of ovarian cancer. There have been dramatic shifts in surgical practice in Western Australia, with more women undergoing certain surgical procedures today than they were 20 years ago. Coupling the increasing surgical trends are improved outcomes. Fewer women are presenting as an emergency, the length of hospital stay has been reduced, and survival outcomes have shown a significant improvement.

Aged↗
PubMed2005

Association between the neuregulin 1 gene and schizophrenia: a systematic review.

Chromosome 8p22-p11 has been identified as a locus for schizophrenia in several genome-wide scans, which has been confirmed by meta-analysis of published linkage data. It appears to be 1 of the most robust linkage findings in psychosis. Several attempts have been made to identify the underlying genetic variation that gives rise to this linkage peak, including systematic fine mapping using extended Icelandic pedigrees that have identified an associated haplotype (HAP(ICE)) in the gene neuregulin 1, also known as heuregulin, glial growth factor, NDF43, and ARIA. Neuregulin 1 (NRG1) is a plausible susceptibility gene because of its involvement in neurodevelopment, regulation of glutamate and other neurotransmitter receptor expression, and synaptic plasticity. Encouragingly, this finding was quickly and directly replicated in a Scottish case-control sample by the same investigators with the same approximately 300 kb associated haplotype. Although in Caucasian populations subsequent attempts at replication of this finding have been difficult to interpret, and no individual functional or causative genetic variants have yet been identified, a summary of HAP(ICE) association results in about 4,500 subjects is consistent with a small (odds ratio approximately 1.5) but significant effect of this haplotype on schizophrenia risk. In Chinese Han populations, where HAP(ICE) is not found, there is good evidence from several studies of association with other markers in the same region. Overall, there is convincing but not yet compelling evidence for a role for NRG1 in susceptibility to schizophrenia. Other genes from this region have also been implicated in schizophrenia, not by systematic mapping but by positional candidate gene analysis; these include MSTP131, frizzled-3, and the calcineurin A gamma subunit gene. Not only are these alternative explanations for the linkage seen between chromosome 8p and schizophrenia, but it is equally possible that there is more than 1 susceptibility gene at this locus.

Case-Control Studies↗
PubMed2007

X-linked infantile spinal muscular atrophy: clinical definition and molecular mapping.

PURPOSE: X-linked infantile spinal-muscular atrophy (XL-SMA) is a rare disorder, which presents with the clinical characteristics of hypotonia, areflexia, and multiple congenital contractures (arthrogryposis) associated with loss of anterior horn cells and death in infancy. We have previously reported a single family with XL-SMA that mapped to Xp11.3-q11.2. Here we report further clinical description of XL-SMA plus an additional seven unrelated (XL-SMA) families from North America and Europe that show linkage data consistent with the same region. METHODS: We first investigated linkage to the candidate disease gene region using microsatellite repeat markers. We further saturated the candidate disease gene region using polymorphic microsatellite repeat markers and single nucleotide polymorphisms in an effort to narrow the critical region. Two-point and multipoint linkage analysis was performed using the Allegro software package. RESULTS: Linkage analysis of all XL-SMA families displayed linkage consistent with the original XL-SMA region. CONCLUSION: The addition of new families and new markers has narrowed the disease gene interval for a XL-SMA locus between SNP FLJ22843 near marker DXS 8080 and SNP ARHGEF9 which is near DXS7132 (Xp11.3-Xq11.1).

Chromosome Mapping↗
PubMed2006

Pregnancy after breast cancer: population based study.

OBJECTIVES: To identify women who survived breast cancer and subsequently conceived and to determine the rate of pregnancy (proportion), management, outcome of the cancer, and outcome of the first subsequent pregnancy. DESIGN: Population based descriptive study with cases identified from the Western Australian data linkage system and validated by review of medical charts. Supplementary data obtained from hospital and clinician records. SETTING: Western Australia, 1982-2003. PARTICIPANTS: Women aged <45 with a diagnosis of breast cancer who subsequently conceived. MAIN OUTCOME MEASURES: Pregnancy outcome and rate, survival, time from diagnosis to pregnancy. RESULTS: Sixty two (54%) women with a diagnosis of breast cancer who subsequently conceived did so less than two years after their diagnosis: 29 of them had an abortion, 27 had a live birth, and six miscarried. Within a proportional hazards regression model subsequent pregnancy was associated with improved overall survival (hazard ratio 0.59, 95% confidence interval 0.37 to 0.95). When the model was stratified by time from diagnosis subsequent pregnancy was associated with improved overall survival in women who waited at least 24 months to conceive (0.48, 0.27 to 0.83) and a non-significant protective effect was seen for women who waited at least six months to become pregnant. CONCLUSIONS: Our study does not support the current medical advice given to premenopausal women with a diagnosis of with breast cancer to wait two years before attempting to conceive. This recommendation may be valid for women who are receiving treatment or have systemic disease at diagnosis, but for women with localised disease early conception, six months after completing their treatment, is unlikely to reduce survival.

Adolescent↗