Validity of clinical psoriatic arthritis diagnoses made by rheumatologists in the Swedish National Patient Register.

OBJECTIVES: : Knowledge of the correspondence between clinical ICD diagnoses and classification criteria fulfilment is crucial to interpret studies identifying cases via ICD codes. We assessed the degree to which patients registered with ICD-10 diagnoses of psoriatic arthritis (PsA) in the Swedish National Patient Register (NPR) fulfil established PsA classification criteria. METHOD: Four hundred patients with at least one outpatient visit to one of five rheumatology or internal medicine departments (three university/two county departments across Sweden) in 2013-2015, with a main ICD-10 diagnosis of PsA (L40.5, M07.0-M07.3), were randomly selected (80 cases/site). Through a structured medical record review, positive predictive values (PPVs) for fulfilment of the following classification criteria were assessed: CASPAR, Moll and Wright, Vasey and Espinoza, and modified ESSG criteria for PsA. A subset analysis regarding CASPAR fulfilment was also performed among cases with available rheumatoid factor and peripheral X-ray status (central CASPAR items; n = 227). RESULTS: Of the 400 patients with a main ICD-10 diagnosis of PsA, 343 (86%) fulfilled at least one of the four PsA classification criteria. PPVs for the different criteria were: CASPAR 69% (82% in the subset analysis), Moll and Wright 51%, Vasey and Espinoza 76%, and modified ESSG 64%. Overall, only 6.5% of the 400 PsA diagnoses were judged as clearly incorrect by the medical record reviewers. CONCLUSION: The validity of rheumatologist-made, clinical ICD-10 diagnoses for PsA in the Swedish NPR is good, with PPVs of 69-82% for CASPAR fulfilment and 86% for meeting any established PsA classification criteria.

Rapid increase in myocardial infarction risk following diagnosis of rheumatoid arthritis amongst patients diagnosed between 1995 and 2006.

UNLABELLED: The risk of ischaemic heart disease (IHD), and in particular myocardial infarction (MI), is increased amongst patients with established rheumatoid arthritis (RA). Few studies have included contemporary patients with RA. We recently reported that the risk of IHD is not elevated before the onset of RA symptoms. However, when, in relation to RA diagnosis, the risk is increased is unknown. OBJECTIVE: To assess the risk of MI and other IHD events amongst patients diagnosed with RA during the last decade and within 18 months following RA symptom onset, compared to the general population, by time since RA diagnosis, year of RA diagnosis and by rheumatoid factor (RF) status. METHODS AND PATIENTS: A Swedish inception cohort of RA (n = 7469) diagnosed between 1995 and 2006 and a matched general population comparator cohort (n = 37,024), was identified and linked to national registers of morbidity and mortality from IHD. Relative risks (RRs) of MI and other IHD events were estimated using Cox regression. RESULTS: During follow-up, 233 patients with RA and 701 controls developed a first MI, corresponding to an overall RR of MI of 1.6 (95% confidence interval 1.4, 1.9). Increased risks of MI were already detected within 1-4 years following RA diagnosis, as well as in patients diagnosed with RA during the last 5 years, in RF-negative patients and for transmural as well as nontransmural MIs. CONCLUSIONS: MI risk increases rapidly following RA diagnosis, suggesting the importance of additional mechanisms other than atherosclerosis. The elevated short-term risk is present amongst patients diagnosed in recent years, underscoring the importance of MI prevention from the time of RA diagnosis.

Common genetic variability in ESR1 and EGF in relation to endometrial cancer risk and survival.

We investigated common genetic variation in the entire ESR1 and EGF genes in relation to endometrial cancer risk, myometrial invasion and endometrial cancer survival. We genotyped a dense set of single-nucleotide polymorphisms (SNPs) in both genes and selected haplotype tagging SNPs (tagSNPs). The tagSNPs were genotyped in 713 Swedish endometrial cancer cases and 1567 population controls and the results incorporated into logistic regression and Cox proportional hazards models. We found five adjacent tagSNPs covering a region of 15 kb at the 5' end of ESR1 that decreased the endometrial cancer risk. The ESR1 variants did not, however, seem to affect myometrial invasion or endometrial cancer survival. For the EGF gene, no association emerged between common genetic variants and endometrial cancer risk or myometrial invasion, but we found a five-tagSNP region that covered 51 kb at the 5' end of the gene where all five tagSNPs seemed to decrease the risk of dying from endometrial cancer. One of the five tagSNPs in this region was in strong linkage disequilibrium (LD) with the untranslated A61G (rs4444903) EGF variant, earlier shown to be associated with risk for other forms of cancer.

Cigarette smoking and breast cancer risk: a population-based study in Sweden.

In a Swedish population-based case-control study, smoking showed no convincing association with risk of postmenopausal breast cancer - regardless of timing or level of smoking exposure - either overall or among subgroups.

Gene expression profiling for prognosis using Cox regression.

Given the promise of rich biological information in microarray data we will expect an increasing demand for a robust, practical and well-tested methodology to provide patient prognosis based on gene expression data. In standard settings, with few clinical predictors, such a methodology has been provided by the Cox proportional hazard model, but no corresponding methodology is available to deal with the full set of genes in microarray data. Furthermore, we want the procedure to be able to deal with the general survival data that include censored information. Conceptually such a procedure can be constructed quite easily, but its implementation will never be straightforward due to computational problems. We have developed an approach that relies on an extension of the Cox proportional likelihood that allows random effects parameters. In this approach, we use the full set of genes in the analysis and deal with survival data in the most general way. We describe the development of the model and the steps in the implementation, including a fast computational formula based on a subsampling of the risk set and the singular value decomposition. Finally, we illustrate the methodology using a data set obtained from a cohort of breast cancer patients.

Breast cancer prognosis in relation to family history of breast and ovarian cancer.

We linked four nationwide Swedish population-based registries to identify first-degree family history of breast and ovarian cancer among breast cancer cases diagnosed between 1991 and 1998 and followed them until death, emigration or end of follow-up in December 1998. The median follow-up was 36 months. Using Cox proportional hazards models, the hazard ratio of death (HR) due to breast cancer was estimated. Women with a family history of breast or ovarian cancer (n=2175, 12.7%) had a nonsignificantly better prognosis than women without any family history, HR 0.86 (95% CI 0.71-1.05); this appeared unrelated to age at diagnosis either in the index case or in relative(s) with breast and/or ovarian cancer. Our study shows that prognostic outlook is not worse among breast cancer patients with family history.

The role of gene-environment interaction in the aetiology of human cancer: examples from cancers of the large bowel, lung and breast.

It has become increasingly clear that cancer can be considered neither purely genetic nor purely environmental. A relatively new area of cancer research has focused on the interaction between genes and environment in the same causal mechanism. Primary candidates for gene-environment interaction studies have been genes that encode enzymes involved in the metabolism of established cancer risk factors. There are common variant forms of these genes (polymorphisms), which may alter metabolism and increase or decrease exposure to carcinogens, thus impacting the risk of cancer. We present an overview of enzymes involved in carcinogen metabolism, present epidemiological tools to evaluate gene-environment interactions, and provide examples from cancers of the breast, lung and large bowel.

Incidence of ovarian cancer among alcoholic women: a cohort study in Sweden.

Linkage of nationwide databases in Sweden allowed us to evaluate the incidence of ovarian cancer among 36,856 women diagnosed with alcoholism between 1965 and 1994. Mean duration of follow-up was 9.6 years, for a total of 317,518 person-years at risk. The expected number of cases of ovarian cancer was calculated by multiplying the number of person-years by 5-year age group and calendar year-specific incidence rates of ovarian cancer in Sweden. The effect measure was the standardized incidence ratio (SIR), with 95% confidence intervals (CIs). Our results indicate an overall deficit of cases of ovarian cancer of about 14% among women with a diagnosis of alcoholism. This deficit is particularly strong and statistically significant among alcoholic women younger than 60 years (SIR = 0.76, 95% CI 0.58-1.00). This deficit is compatible with the reported reduction of gonadotrophin levels among alcoholic women younger than 60 years and with the hypothesis invoking these gonadotrophins in the etiology of ovarian cancer.

Estrogen receptor alpha gene polymorphisms and endometrial cancer risk.

Since the estrogen receptor alpha (ER) is an important mediator of hormonal responses such as proliferation in estrogen-sensitive tissues, we hypothesized that polymorphisms in the ER gene could be functional and associated with endometrial cancer risk. We performed a population-based case-control study in Sweden, focusing on restriction fragment length polymorphisms for XbaI and PvuII and an upstream TA repeat polymorphism. In the main analysis, 154 cases and 205 controls who never used hormone replacement therapy took part and we calculated age-adjusted and multivariate odds ratios (OR) and 95% confidence intervals (CI) using unconditional logistic regression. The XbaI X allele appeared to confer a reduced risk for endometrial cancer. The multivariate OR for the XX genotype was 0.52 (95% CI 0.21-1.29) compared to the xx genotype and there were suggestions of decreasing risk with increasing number of X alleles (P for trend = 0.07). The PvuII PP genotype was also associated with a non-significantly decreased risk for endometrial cancer (multivariate OR 0.70, 95% CI 0.34-1.44) compared with the pp genotype (P for trend = 0.43). The multivariate OR for two short TA (<19 repeats) alleles versus two long alleles was 1.54 (95% CI 0. 73-3.27) and there were suggestions of increasing risk with increasing number of short alleles (P for trend = 0.26). We observed the same pattern of results in an expanded group of subjects, which included women who had used hormone replacement (in total 288 cases and 392 controls). Our data suggest that variants of the ER gene may be associated with an altered risk of endometrial cancer.