1,721,019 research outputs found
Web-based resources to assist the statistical analysis and presentation of data.
No full textThe intention of this article is to highlight sources of web-based reference material, courses and software that will aid statisticians and researchers. The article includes websites that: assist in writing a protocol or proposal; link to online statistical textbooks; and provide statistical calculators or links to free statistical software and other guidance documents
Does lithium therapy protect against the onset of dementia
No full textLithium compounds might theoretically play a role in preventing dementia by inhibiting formation both of beta amyloid and hyper phosphorylated tau protein. We carried out a case-control study to assess any possible clinical effects of lithium therapy on the diagnosis of dementia, using data from the General Practice Research Database, which collects routine data from primary care patients in the UK. Patients who received lithium had a higher risk of a diagnosis of dementia compared with those who did not (adjusted odds ratio 1.8, 95% CI 1.1-2.8). There was a trend toward increasing risk with increasing numbers of lithium prescriptions. This evidence does not support the use of lithium for preventing dementia
Issues with using baseline in last observation carried forward analysis
No full textThe topic of this paper was prompted by a study for which one of us was the statistician. It was submitted to Annals of Internal Medicine. The paper had positive reviewer comment; however, the statistical reviewer stated that for the analysis to be acceptable for publication, the missing data had to be accounted for in the analysis through the use of baseline in a last observation carried forward imputation. We discuss the issues associated with this form of imputation and recommend that it should not be undertaken as a primary analysis
Consultations for middle ear disease, antibiotic prescribing and risk factors for reattendance: a case-linked cohort study
No full textBackground
Otitis media is the most common reason for children to receive antibiotics, but there is no evidence about the effect of prescribing on reattendance.Aim
To evaluate the changing workload of middle ear disease in general practice, and the impact on surgery reattendance of prescribing antibiotics at first attendance.Design of study
A case-linked cohort analysis for antibiotic prescribing versus no prescribing at first consultation event.Setting
Two hundred and ninety-one practices spread throughout the UK recording for the General Practice Research Database (GPRD) and incorporating individual patient data records for 2 265 574 patients.Method
All middle ear disease coded events that can be classed within acute otitis media (AOM) or glue ear sub-categories (and excluding chronic suppurative otitis media) were selected for analysis when the first event was from 1991–2001. The effect of antibiotic prescription on the risk of reattendance using Cox proportional hazards regression was analysed.Results
Total consultations for AOM have fallen markedly over this decade, and glue ear consultations have risen but by a much smaller extent (26 000 decrease versus 4000 increase in consultations per year), which makes re-labelling an unlikely explanation of the fall in AOM consultations. In the 2–10 years age range, consultations for AOM fell from 105.3 to 34.7 per 1000 per year, with glue ear consultations unaltered (15.2 to 16.7 per 1000 per year). Antibiotic prescribing for AOM has stayed remarkably constant (80–84% of consultations), but antibiotic prescribing for glue ear has risen sharply (13 to 62%). Prescribing antibiotics increased the risk of reattendance for AOM (hazard ratio [HR] = 1.09, 95% confidence interval [CI] = 1.07 to 1.10) and has reduced the risk of reattendance for glue ear (HR = 0.92, 95% CI = 0.88 to 0.96).Conclusion
Prescribing antibiotics for AOM probably increased reattendance, but the opposite effect has been noted for glue ear, which suggests a treatment effect of antibiotics in glue ear. Further research is needed to clarify whether this possible benefit is worth the known harms, and if so in which subgroups of children
Association between dementia and infectious disease: evidence from a case-control study
No full textInflammation plays a part in the etiology of dementia. Whether this is the primary pathogenesis, or a secondary reaction is unclear. We postulate that since systemic infection can provoke the enhanced synthesis of inflammatory mediators in the brain, such diseases may promote the onset of dementia.We carried out a nested case-control study using the General Practice Research Database. Cases were patients with incident dementia, and controls without such a diagnosis. Infectious episodes in the four years preceding diagnosis were counted using diagnostic codes, or prescription codes for anti-infective drugs. We considered age, sex, smoking, diabetes mellitus, and frequency of consultation as potential confounders.There were 9954 valid cases, and 9374 valid controls. Cases were on average older, more likely to be female, to smoke and to have diabetes, than the controls. There was an increased risk of diagnosis of dementia in those patients older than 84 with infections (OR for 2 or more infections compared with 0 or 1 = 1.4, 95% CI 1.2 to 1.7). Smoking and diabetes mellitus were also shown to markedly increase the risk of diagnosis of dementia.We have shown a positive association between episodes of infection and increased likelihood of diagnosis of dementia in the very elderly. Smoking and diabetes mellitus are associated with onset of dementia in the elderly. The evidence from this study may represent cause and effect, since there is a credible biologic explanation
EQ-5D versus SF-6D in an older, chronically ill patient group
No full textChoosing between preference-based instruments of health-related quality of life (HR-QOL) in particular situations is an important area for research. Even where instruments can be assumed to be measuring the same thing, they may not be interchangeable. The study presented investigates the extent to which EQ-5D and SF-6D instruments are interchangeable in an older, chronically ill patient group undergoing haemodialysis. Head-to-head comparisons were made using ‘practicality’, ‘descriptive validity’, ‘empirical validity’, mean utilities and associated distributions. Overall it was difficult to choose between instruments on the basis of descriptive or empirical validity, since both performed similarly. Important differences were, however, found relating to practicality: a significantly higher response rate in favour of EQ-5D; and lower levels of missing data to derive health states. Non-response was significantly associated with age and co-morbidity of respondents. We suggest that in patients undergoing haemodialysis, and potentially other older chronically ill patient groups, EQ-5D is the primary preference-based generic HR-QOL instrument
A population-based study of the incidence and outcomes of diagnosed chronic kidney disease
No full textBackground: This study aims to determine the incidence rate and prognosis of detected chronic kidney disease (CKD) in a defined population.Methods: This is a retrospective cohort study of all new cases of CKD from Southampton and South-West Hampshire Health Authority (population base, 405,000) determined by a persistently increased serum creatinine (SCr) level (?1.7 mg/dL [?150 µmol/L] for 6 months) identified from chemical pathology records. Follow-up was for a mean of 5.5 years for survival, cause of death, and acceptance to renal replacement therapy (RRT).Results: The annual incidence rate of detected CKD was 1,701 per million population (pmp; 95% confidence interval [CI], 1,613 to 1,793) and 1,071 pmp (95% CI, 1,001 to 1,147) in those younger than 80 years. There was a steep age gradient; median age was 77 years. The man-woman rate ratio was 1.6 (95% CI, 1.4 to 1.8), with a male excess in all age groups older than 40 years. Incidence increased in areas with greater socioeconomic deprivation. Median survival was 35 months. Age, SCr level, and deprivation index were all significantly associated with survival. Standardized mortality ratios were 36-fold in those aged 16 to 49 years, 12-fold in those aged 50 to 64 years, and more than 2-fold in those older than 65 years. Cardiovascular disease (CVD) was the most common cause of death (46%). Only 4% of patients were accepted to RRT.Conclusion: The incidence of diagnosed CKD is common, especially in the elderly, and is greater in more deprived areas. Prognosis is poor, with CVD prominent. More research is needed to assess the effectiveness and costs of increasing referral to nephrologists of patients with CKD
Frequency and impact of nonadherence to immunosuppressants after renal transplantation: a systematic review
No full textNonadherence to immunosuppressants is recognized to occur after renal transplantation, but the size of its impact on transplant survival is not known. A systematic literature search identified 325 studies (in 324 articles) published from 1980 to 2001 reporting the frequency and impact of nonadherence in adult renal transplant recipients. Thirty-six studies meeting the inclusion criteria for further review were grouped into cross-sectional and cohort studies and case series. Meta-analysis was used to estimate the size of the impact of nonadherence on graft failure. Only two studies measured adherence using electronic monitoring, which is currently thought to be the most accurate measure. Cross-sectional studies (n=15) tended to rely on self-report questionnaires, but these were poorly described; a median (interquartile range) of 22% (18%-26%) of recipients were nonadherent. Cohort studies (n=10) indicated that nonadherence contributes substantially to graft loss; a median (interquartile range) of 36% (14%-65%) of graft losses were associated with prior nonadherence. Meta-analysis of these studies showed that the odds of graft failure increased sevenfold (95% confidence interval, 4%-12%) in nonadherent subjects compared with adherent subjects. Standardized methods of assessing adherence in clinical populations need to be developed, and future studies should attempt to identify the level of adherence that increases the risk of graft failure. However, this review shows nonadherence to be common and to have a large impact on transplant survival. Therefore, significant improvements in graft survival could be expected from effective interventions to improve adherence
Technical and measurement report. Simple anatomical information improves the accuracy of locating specific spinous processes during manual examination of the low back
No full textThe objective of the study was to test whether a teaching protocol including simple anatomical information on the surface anatomy of spinous processes, improves physiotherapy students' ability to accurately locate selected thoracic and lumbar spinal segments - T12 and L3. First year physiotherapy students were allocated to Group 1 (n=35) and Group 2 (n=34). Both groups were taught to identify spinous processes by counting up from the sacrum, but Group 2 received supplementary anatomical information on the shapes and vertical length of the tips of L5 to T12 spinous processes. The spinous processes of L3 and T12 were located by two experienced physiotherapists and marked on a model using an invisible skin marker. Volunteer students were asked to locate these spinous processes and accuracy was confirmed using an ultraviolet lamp. Students with supplementary anatomical information (Group 2) were significantly better at locating T12 (difference in proportions 36% (95% confidence interval 14 to 51%)) and both T12 and L3 (difference in proportions 33% (11 to 48%)). Group 2 students were also better than Group 1 students at locating L3 (difference in proportions 28% (4 to 48%)), but the difference was not significant. Including simple anatomical information when teaching manual examination skills improved the accuracy of locating specific low back spinal levels
Correlation between upper limb functional ability and structural hand impairment in an early rheumatoid population
No full textObjective: To explore the relationship in individuals with early rheumatoid arthritis (RA) between self-report upper limb function, therapist-assessed upper limb function and therapist-assessed measures of structural impairment (handgrip, active hand motion and metacarpophalangeal (MCP) joint ulnar deviation). Design: Thirty-six patients with early RA were recruited across seven outpatient occupational therapy departments. Outcome measures: Upper limb functional activity and ability was measured using the Disability of the Arm, Shoulder and Hand (DASH) questionnaire and the Grip Ability Test (GAT). Upper limb impairment was assessed by bilateral power handgrip using the MIE Digital Grip Analyser, goniometry measures of bilateral metacarpophalangeal (MCP) joint ulnar deviation and bilateral active motion of the wrist. Results: Strong correlations (> 0.7) were seen between the self-report DASH questionnaire and the therapist-rated GAT assessment. Bilateral power handgrips were also strongly correlated with both functional assessments. Dominant ulnar deviation at the MCP joints demonstrated a weak correlation (0.3–0.4) with both self-report and therapist-rated functional ability and a weak to moderate. (0.1 – 0.5) correlation on the nondominant side. Conclusion: In this early RA population handgrip strength is an accurate indicator of upper limb ability. Ulnar deviation at the MCP joints shows only a weak to moderate association with upper limb functional activity and ability. Although the DASH and the GAT were strongly correlated, the DASH was a more discriminating measure than the GAT in assessing upper limb ability in this sample population. <br/
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