Paired Case-control Design Research Articles

Key management practices to reduce the risk of the occurrence of Rumex obtusifolius in productive grasslands

AbstractRumex obtusifolius (broad‐leaved dock) is a problematic weed that reduces yield and nutritional value of forage in grasslands of temperate regions worldwide. We conducted an on‐farm study to identify management practices and environmental factors that influence the risk of the occurrence of R. obtusifolius in high densities in permanent, productive grasslands used for forage production. Following a common protocol, a paired case–control design was implemented in Switzerland (CH), Slovenia (SI), and United Kingdom (UK) to compare parcels with high densities of R. obtusifolius (cases, ≥1 plant m−2) with nearby parcels free of or with very low densities of the species (controls, ≤4 plants 100 m−2). A total of 40, 20, and 18 pairs were recorded in CH, SI, and UK respectively. Parameters measured included data about management practices and history, vegetation cover and composition, and soil nutrients and texture. Across countries, increased vegetation cover reduced the relative risk of R. obtusifolius occurrence. By contrast, increased soil phosphorus and potassium and high soil bulk density raised the relative risk. These effects were consistent across countries, as no interactions between country and any of the factors were observed. The two indicator species for case parcels, Plantago major and Poa annua, were typical species of disturbed areas and fertile soils, while indicators for control parcels were characteristic of grasslands under medium to high management intensity (e.g., Festuca rubra, Cynosorus cristatus, Anthoxantum odoratum). We conclude that the risk for grassland infestation with R. obtusifolius can be significantly affected by management practices. Prevention measures should target phosphorus and potassium fertilisation to the forage plants' requirements, minimise soil compaction, and maintain dense swards.

Can the soil seed bank of Rumex obtusifolius in productive grasslands be explained by management and soil properties?

Rumex obtusifolius is a problematic weed in temperate grasslands worldwide as it decreases yield and nutritional value of forage. Because the species can recruit from the seed bank, we determined the effect of management and soil properties on the soil seed bank of R. obtusifolius in intensively managed, permanent grasslands in Switzerland (CH), Slovenia (SI), and United Kingdom (UK). Following a paired case-control design, soil cores were taken from the topsoil of grassland with a high density of R. obtusifolius plants (cases) and from nearby parcels with very low R. obtusifolius density (controls). Data on grassland management, soil nutrients, pH, soil texture, and density of R. obtusifolius plants were also collected. Seeds in the soil were germinated under optimal conditions in a glasshouse. The number of germinated seeds of R. obtusifolius in case parcels was 866 ±152 m-2 (CH, mean ±SE), 628 ±183 m-2 (SI), and 752 ±183 m-2 (UK), with no significant difference among countries. Densities in individual case parcels ranged from 0 up to approximately 3000 seeds m-2 (each country). Control parcels had significantly fewer seeds, with a mean of 51 ±18, 75 ±52, and 98 ±52 seeds m-2 in CH, SI, and UK, respectively, and a range between 0 and up to 1000 seeds m-2. Across countries, variables explaining variation in the soil seed bank of R. obtusifolius in case parcels were soil pH (negative relation), silt content (negative), land-use intensity (negative), and aboveground R. obtusifolius plant density (positive). Because a large soil seed bank can sustain grassland infestation with R. obtusifolius, management strategies to control the species should target the reduction in the density of mature plants, prevention of the species' seed production and dispersal, as well as the regulation of the soil pH to a range optimal for forage production.

Influence of socio- demographic factors on cerebral palsy among children

Cerebral palsy is a group of disorders that affect movement and muscle tone or posture. It is caused by damagethat occurs to the immature, developing brain, most often before birth. The present study investigated the influence ofsocio-demographic factors like family type, family size, socio-economic status, and religion on cerebral palsy amongchildren in Dharwad taluk during 2021-22. The sample size was 164 children of 6 to 16 years, on which 82 were cerebralpalsy and 82 were typical children matched with cerebral palsy children. A descriptive matched pair case control design wasused. Self- structured questionnaire and Agarwal’s socio-economic status scale was used for data collection. The result ofthe study revealed that, the incidence of cerebral palsy was high among males (67.10%) than females (32.90%) also firstborn (56.10%) had more risk than later born (43.90%). Majority of families were (84.10%) nuclear with medium size(56.90%). The incidence of cerebral palsy was high among low socio-economic status hence, found a strongassociationbetween cerebral palsy and socio-economic status. Risk factors for cerebral palsy among children when compared tomedium and high socio-economic status

Factors associated with care-seeking for low back pain when genetics and the familial environment are considered

BackgroundLow back pain (LBP) is the leading cause of disability worldwide. Care-seekers for LBP cause substantial economic burden to governments and the healthcare system. ObjectiveTo investigate lifestyle and health-related factors associated with care-seeking (including pain medication use) in individuals experiencing LBP, after controlling for important genetic and early environmental confounders through the use of a within-twin pair case-control design. DesignA secondary analysis of observational longitudinal data, derived from the Australian Twin low BACK pain (AUTBACK) study, was performed on 66 twin pairs that presented with similar symptoms of LBP at baseline but became discordant for care-seeking behaviour over one month. MethodsSubjective and objective assessment of pain intensity, disability, depression, sleep quality, physical activity and body mass index were performed. Data was analysed using stepwise conditional logistic regression in two stages: within-pair case–control for monozygotic and dizygotic twins together; and within-pair case–control analysis of monozygotic twins only. Results were expressed as odds ratios (OR) and 95% confidence intervals (CI). ResultsHigher LBP intensity (OR 2.9; 95% CI 1.3–6.8) and poorer sleep quality (OR 10.9; 95% CI 1.5–77.7) were the main factors that increased the likelihood of care-seeking for LBP. These associations remained significant and increased in magnitude after adjusting for genetic confounding. ConclusionsIndividuals with higher LBP intensity and worse sleep quality are more likely to seek care for LBP, and this relationship is likely to be causal after adjustment of familial and genetic confounding.

Cell therapy for posttraumatic shoulder osteonecrosis

This study compared the clinical and radiological results of bone marrow mesenchymal stem cell implantation with traditional simple core decompression (CD) using a matched pair case-control design for osteonecrosis of the humeral head (ONHH) after fracture of the proximal humerus. We retrospectively reviewed 64 patients who had surgery for ONHH. Thirty patients had been treated with cell therapy between 2010 and October 2015, with 18 patients at pre-collapse stage (8 stages-I, 10 stages-II), and 12 patients at post-collapse stages (7 stages-III and 5 stages-IV). Using a matched pair case-control design, these 30 study patients were compared to 34 other patients who were treated with simple core decompression (CD) without cells (control group). The cell therapy group was treated with percutaneous mesenchymal cell (MSCs) injection obtained from bone marrow (BM) concentration. During a mean follow-up duration of 7years (5 to 10years), radiographs performed each year were used to evaluate the radiological results; the Constant score and visual analogue scale were chosen to assess the clinical results. We assessed stage progression, collapse and arthroplasty conversion rate. Survivor rate analysis was performed using these parameters as the primary endpoints. Among the 30 shoulders included in the cell therapy group, three (10%) humeral heads had collapsed at the most recent follow-up, versus 25 (74%) in 34 shoulders after simple core decompression (P<0.0001). As consequence, we observed statistically significant difference (P=0.0001) in the humeral head survival (absence of arthroplasty conversion) rate at the end time point between the cell therapy group (93% survival) and simple core decompression (26% survival). Better results were obtained for early stages (stages I and II) osteonecrosis without collapse at baseline. Core decompression with cell therapy was a safe and effective procedure for treatment in the pre-collapse stages of posttraumatic shoulder osteonecrosis and improved the outcome of the disease as compared with simple core decompression without cells.

Mental disorders and suicide attempt in rural China

The prevalence of various mental disorders and their age and gender specific characteristics among suicide attempters remains unclear in rural China. This study using 1:1 paired case-control design included 409 suicide attempters and 409 paired controls matched on age, gender and place of residence. Mental disorders were assessed using the Structured Clinical Interview for DSM-IV-TR Axis I Disorders. The prevalence of mental disorders was 32.3% for suicide attempters and 4.9% for paired controls. Mental disorder constituted a significant risk factor for suicide attempt with an adjusted odds ratio of 7.16 (95%CI: 3.65–14.04). The prevalence of mental disorders was higher among male than female suicide attempters. Major depressive disorder was most common in female suicide attempters while alcohol use disorder was most common in the males. The prevalence of mental disorders seemed to increase with age. Suicide attempters of higher ages were more prone to have mood disorders, especially a major depression. Suicide attempters with mental disorders differed from those without mental disorders on a number of socio-economic characteristics and suicidal behavior features. These insights should be taken into account in strategies and efforts to improve mental health care and ultimately to reduce suicidal behavior among residents in rural China.

Analysing the effect of multiple sclerosis on vitamin D related biochemical markers of bone remodelling

The Irish population is at risk of vitamin D deficiency during the winter months, but the secular trend over the past 40 years is for marked improvement. Multiple sclerosis (MS) is common in Ireland with a latitudinal pattern favouring highest incidence in northern regions; MS is linked strongly with vitamin D status as a causal factor. We sought firstly to study the relationship between vitamin D status and vitamin D-related bone biochemistry, and secondly to evaluate if MS had an independent effect on vitamin D related markers of bone remodelling. Using a case-control design of 165 pairs (MS patient and matched control) residing in three different geographic regions during winter months, we measured serum 25-hydroxyvitamin D (25OHD), parathyroid hormone (PTH), C-terminal telopeptide of type I collagen (CTX) and total procollagen type I amino-terminal propeptide (PINP). Given the paired case-control design, associations were explored using mixed-effects linear regression analysis with the patient-control pair as a random effect and after log transformation of 25OHD. A two-way interaction effect was tested for vitamin D status (25OHD <30nmol/L) and the presence of MS on PTH, CTX, and PINP. In the total group, just over one-third (34.5%) had 25OHD <30nmol/L. PTH was elevated in 7.6%. CTX was not elevated in any case, and PINP was elevated in 4.5%. On mixed-effects linear regression analysis after adjusting for confounders (age, sex, renal function, and serum albumin), we demonstrated the principal determinant of 25OHD was geographical location (p<0.001), of PTH was 25OHD (p<0.001), of CTX was PTH (p<0.001), and of PINP was PTH (p<0.001). MS did not have an independent effect on PTH (p=0.921), CTX (p=0.912), or PINP (p=0.495). As regards an interaction effect, the presence of MS and 25OHD <30nmol/L was not significant but tended towards having lower PTH (p=0.207). In conclusion, in Ireland in winter only a minority had any abnormality in the secondary indices of vitamin D deficiency, and MS had no independent effect on parathyroid status or bone remodelling activity.

Factors Associated With 7-Day Rehospitalization After Heart Failure Admission.

Rehospitalizations within 7 days after discharge may reflect the quality of hospital care. We examined factors associated with 7-day readmissions after discharge for heart failure (HF). Using a matched pair case-control design, we examined health records for sociodemographic, clinical, and health system factors for patients with a primary diagnosis of HF (ICD-10 I50) discharged alive from all acute care hospitals in Calgary, Alberta, from 2004 to 2012. Logistic regression was used to identify variables associated with 7-day all-cause readmission. We included 382 patients, or 191 in matched pairs, with 41% of readmissions due to HF. Frailty (adjusted odds ratio [aOR], 2.30; 95% confidence interval [CI], 1.41-3.76) and attending physician as specialist (aOR, 2.10; 95% CI, 1.32-3.42) were associated with increased likelihood of readmission. Reduced likelihood of readmission was associated with documented instructions for follow-up with a family physician within 1 week of discharge (aOR, 0.56; 95% CI, 0.36-0.88). All 3 factors were easily abstracted from all patient records, including frailty, which was defined as all 3 of age older than 75 years, 3 or more comorbid conditions, and requiring assistance with activities of daily living. Very early readmission to hospital after HF admission is associated with 3 factors that may be easily identified in patient records.

Active Season Microhabitat and Vegetation Selection by Giant Gartersnakes Associated with a Restored Marsh in California

Abstract Studies of habitat selection can reveal important patterns to guide habitat restoration and management for species of conservation concern. Giant gartersnakes Thamnophis gigas are endemic to the Central Valley of California, where &amp;gt;90% of their historical wetland habitat has been converted to agricultural and other uses. Information about the selection of habitats by individual giant gartersnakes would guide habitat restoration by indicating which habitat features and vegetation types are likely to be selected by these rare snakes. We examined activity patterns and selection of microhabitats and vegetation types by adult female giant gartersnakes with radiotelemetry at a site composed of rice agriculture and restored wetlands using a paired case-control study design. Adult female giant gartersnakes were 14.7 (95% credible interval [CRI] = 9.4–23.7) times more likely to be active (foraging, mating, or moving) when located in aquatic habitats than when located in terrestrial habitats. Microhabitats associated with cover—particularly emergent vegetation, terrestrial vegetation, and litter—were positively selected by giant gartersnakes. Individual giant gartersnakes varied greatly in their selection of rice and rock habitats, but varied little in their selection of open water. Tules Schoenoplectus acutus were the most strongly selected vegetation type, and duckweed Lemna spp., water-primrose Ludwigia spp., forbs, and grasses also were positively selected at the levels of availability observed at our study site. Management practices that promote the interface of water with emergent aquatic and herbaceous terrestrial vegetation will likely benefit giant gartersnakes. Given their strong selection of tules, restoration of native tule marshes will likely provide the greatest benefit to these threatened aquatic snakes.

Acute and longitudinal changes in motor cortex function following mild traumatic brain injury

Primary objective: To evaluate excitability and inhibition of the motor cortex acutely and longitudinally following mild traumatic brain injury (mTBI).Research design: A longitudinal paired case-control design was used to examine cortical excitability and inhibition in 15 adults who had sustained an mTBI (mean age = 20.8 ± 1.2 years) and 15 matched control participants (mean age = 21.1 ± 1.3 years).Methods and procedures: Participants visited the lab within 72 hours of injury and again at 1, 2, 4 and 8 weeks post-injury. During each visit, transcranial magnetic stimulation was used to examine resting motor threshold (RMT), motor evoked potential peak-to-peak amplitude (MEPamp) and cortical silent period (CSP) duration of the first dorsal interosseous muscle.Main outcomes and results: There were no differences between groups in RMT (p = 0.10) or MEPamp (p = 0.22) at 72 hours post-injury or across the 2-month testing period (p ≥ 0.68), indicating similar cortical excitability. However, the CSP duration was higher in individuals with mTBI, indicating greater intra-cortical inhibition compared with the control group at 72 hours post-injury (p = 0.03) and throughout the 2 months of recovery (p = 0.009).Conclusions: mTBI appeared to have little effect on cortical excitability, but an acute and long-lasting effect on intra-cortical inhibition.

Cumulative logit model in the analysis of endometrial cancer under a matched pair case-control design

Background: Binary as well as polytomous logistic models are widely used for estimating odds ratios when the exposure of prime interest assumes unordered multiple levels under matched pairs case-control design. In our previous studies, we have shown that the use of a polytomous logistic model for estimating cumulative odds ratios when the outcome (response) variable is ordinal (in addition to being polytomous) under matched pairs case-control design. The cumulative odds ratios were estimated based on separate fitting of the model at each of the cutpoint level as compared to less than equal to that level. In this paper we propose an alternative method of estimating the cumulative odds ratios and reanalyze the Los Angeles Endometrial Cancer data in the context of dose levels of conjugated oestrogen exposure and development of endometrial cancer under the matched pair case-control design. Methods: In the present study, the cumulative logit model is fitted using a single multinomial logit model for the data. For this, the full maximum likelihood estimation procedure is adopted. A test for equality of the cumulative odds ratios across the exposure levels is proposed. Results: The analysis revealed that there is a strong evidence of risk for developing endometrial cancer due to oestrogen exposure above each of the three dose level as compared to less than equal to that level. The estimated values at the three cutpoint levels were found to be 6.17, 3.60 and 5.16 respectively. Conclusions: The odds of developing endometrial cancer are very high for the users of any amount of oestrogen, even if it is the least dose, as compared to the non-users.

Do brain activation changes persist in athletes with a history of multiple concussions who are asymptomatic?

Primary objective: To evaluate brain activation patterns of asymptomatic athletes with a history of two or more concussions.Research design: A paired case-control design was used to evaluate brain activation patterns during cognitive performance in 14 athletes with a history of two or more concussions and 14 age- and sex-matched controls with no previous concussion.Methods and procedures: Percentage Blood-Oxygen-Level-Dependent (BOLD) change during an N-back working memory task was assessed in all participants. Performance on the Trail-Making Test Form A and B, Symbol-Digit Modalities Test and the Immediate Post-concussion Assessment and Cognitive Test (ImPACT) was also compared between groups.Main results: As expected, brain regions activated during the performance of the N-back were equivalent between groups. The groups performed similarly on the neurocognitive measures. The history of concussion group was less accurate than controls on the 1-, 2- and 3-back conditions of the N-back.Conclusions: Following the complete resolution of symptoms, a history of two or more concussions is not associated with changes in regional brain activation during the performance of working memory task. Compensatory brain activation may only persist during the typically brief time athletes experience symptoms following concussion.

Is Intravenous Iron Useful for Reducing Transfusions in Surgically Treated Colorectal Cancer Patients?

The goal of the present study was to determine whether the intravenous administration of iron in the postoperative period of colon cancer surgical patients suffices to reduce the number of transfusions necessary. The study was designed as a retrospective observational study conducted over a three-year period. A paired case-control design was used to analyze the effect of postoperative iron on patients' blood transfusion needs. Two groups were established (the case group, which received postoperative iron and the control group, which did not) and matched for age (± 3 years), gender, type of operation, tumor stage, and surgical approach. Of 342 patients who underwent operation, 104 paired patients were obtained for inclusion in this study (52 in each group). A second analysis was made to assess the effect of intravenous iron on the evolution of hemoglobin between the first postoperative day and hospital discharge in the subgroup of patients with reduction in hemoglobin, in subjects without preoperative or postoperative transfusions. Finally, a total of 71 patients were paired in two groups: 37 and 31 patients in case and control, respectively. The mean hemoglobin concentration at discharge for the case group was 10 ± 1.1 g/dl, vs. 10.6 ± 1.2 in the controls (P = 0.012). The number of transfusions in the case group was 3 ± 1.6, vs. 3.3 ± 3 in the control group (P = 0.682). Thus, 28.8 % of the patients in the case group received transfusions, versus 30.8 % of those in the control group (P = 0.830). In the second analysis, the decrease in hemoglobin concentration was 0.88 g/dl and 0.82 g/dl in case and control, respectively. Intravenous iron does not appear to reduce the blood transfusion requirements in the postoperative period of colorectal surgery patients with anemia. We consider that further studies are needed to more clearly define the usefulness of intravenous iron in reducing the transfusion needs in such patients.

Exploring Brain Activation Patterns In Asymptomatic Athletes With And Without A History Of Multiple Concussions

The long-term effects of multiple concussions in athletes are unclear. Functional magnetic resonance imaging (fMRI) studies have previously reported compensatory brain activation patterns and brain activation (i.e., engagement) differences in symptomatic athletes with a history of multiple concussions. Interestingly, these fMRI findings have been documented in absence of neurocognitive impairment. No fMRI study has examined brain activation patterns in athletes with a history of concussion who are asymptomatic (i.e., recovered from concussion). PURPOSE: To evaluate neurocognitive performance and compensatory brain activation patterns elicited by a working memory task in asymptomatic athletes with and without a history of two or more concussions. METHODS: A paired case-control design was used for study. Fourteen athletes with a history of two or more concussions were matched (age, sex) to 14 athletes with no history of concussion. All athletes were administered the Trail-Making Test Form A and B, Symbol Digit Modalities Test, and ImPACT prior to fMRI. On a separate testing occasion all athletes performed the N-back working memory during fMRI. RESULTS: Similar performance on the Trail Making Test Form A and B, Symbol Digit Modalities Test, and ImPACT were observed in both groups. The history of concussion group was less accurate than controls on the low (p =.01), moderate (p =.04), and high (p =.02) working memory conditions of the N-back task. No compensatory brain activation patterns were observed between groups, and common brain regions used to perform the task were used to the same degree during low, moderate, and high working memory demands. CONCLUSIONS: Following the resolution of symptoms, a history of two or more concussions is not associated with reduced neurocognitive performance. Functional MRI data revealed no compensatory or engagement differences during a working memory task in these athletes. However, behavioral differences on the N-back are not explained by fMRI and warrants further study.

Risk factors for pneumothorax in very low birth weight infants*

To identify risk factors for pneumothorax in very low birth weight infants. Retrospective case-control study. Neonatal intensive care unit in a pediatric tertiary care center. Very low birth weight infants. All very low birth weight infants with pneumothorax born during the period January 1997 through December 2002 were identified. These infants were matched to infants without pneumothorax for gestational age, birth weight, and gender. Perinatal, neonatal, and treatment variables were collected for all infants. Very low birth weight infants with pneumothorax were compared with those without. Univariate analysis was performed using the paired Student's t-test for continuous variables and the McNemar test for categorical variables. All variables were entered into a stepwise logistic regression model using a paired case-control design. Statistical significance was defined at p < .05. Seventy-four of 679 very low birth weight infants (10.9%) admitted to the neonatal intensive care unit developed a pneumothorax and were matched to 74 control infants. Multivariate analysis showed that only factors present on the day of pneumothorax were associated with pneumothorax. An increased risk of pneumothorax was associated with maximal, peak inspiratory pressure (odds ratio [OR] 1.33, 95% confidence interval [CI] 1.07, 1.66), minimal Fio2 (OR 2.18, 95% CI 1.14, 4.17), pulmonary hemorrhage (OR 27.5, 95% CI 2.3, 337), and maximal arterial CO2 (OR 1.94, 95% CI 1.13, 3.34), while a decreased risk was associated with maximal positive end-expiratory pressure (OR 0.71, 95% CI 0.56, 0.91). Pneumothorax is associated with factors present on day of pneumothorax and not with initial ventilation variables or initial severity of lung disease. Decreasing the risk of pneumothorax requires rigorous control of ventilation, including optimizing positive end-expiratory pressure and minimizing peak inspiratory pressure.

Cumulative logit models for matched pairs case-control design: Studies with covariates

Binary as well as polytomous logistic models have been found useful for estimating odds ratios when the exposure of prime interest assumes unordered multiple levels under matched pair case-control design. In our earlier studies, we have shown the use of a polytomous logistic model for estimating cumulative odds ratios when the exposure of prime interest assumes multiple ordered levels under matched pair case-control design. In this paper, using the above model, we estimate the covariate adjusted cumulative odds ratios, in the case of an ordinal multiple level exposure variable under a pairwise matched case-control retrospective design. An approach, based on asymptotic distributional results, is also described to investigate whether or not the response categories are distinguishable with respect to the cumulative odds ratios after adjusting the effect of covariates. An illustrative example is presented and discussed.

P.1.065 Safety of sertraline in overdose in a 13 years old adolescent — comparative toxicity study of antidepressants among children and adolescents

The prevalence of various mental disorders and their age and gender specific characteristics among suicide attempters remains unclear in rural China. This study using 1:1 paired case-control design included 409 suicide attempters and 409 paired controls matched on age, gender and place of residence. Mental disorders were assessed using the Structured Clinical Interview for DSM-IV-TR Axis I Disorders. The prevalence of mental disorders was 32.3% for suicide attempters and 4.9% for paired controls. Mental disorder constituted a significant risk factor for suicide attempt with an adjusted odds ratio of 7.16 (95%CI: 3.65–14.04). The prevalence of mental disorders was higher among male than female suicide attempters. Major depressive disorder was most common in female suicide attempters while alcohol use disorder was most common in the males. The prevalence of mental disorders seemed to increase with age. Suicide attempters of higher ages were more prone to have mood disorders, especially a major depression. Suicide attempters with mental disorders differed from those without mental disorders on a number of socio-economic characteristics and suicidal behavior features. These insights should be taken into account in strategies and efforts to improve mental health care and ultimately to reduce suicidal behavior among residents in rural China.