Prospective Matched Cohort Study Research Articles

Risk of contrast induced nephropathy in the critically ill: a prospective, case matched study

IntroductionComputerized tomography is frequently employed in the critically ill, often using intravenous radiocontrast material. Many of these patients have clinical features that are considered risk factors for contrast induced nephropathy, but are simultaneously at risk for renal injury from other factors related to their acute illnesses. The attributable risk for renal dysfunction from radiocontrast exposure has not been well quantified in this population.MethodsA prospective matched cohort study was conducted of patients scanned with or without radiocontrast enhancement while receiving intensive care in a Veterans Affairs Medical Center. Patients were matched for pre-scan measured creatinine clearance, diabetes, mechanical ventilation, and vasopressor use. Measured clearance was followed for three days after scanning. Evolution of nephropathy, as determined by change in measured clearance, was compared within matched pairs.ResultsFifty-three pairs of patients satisfied matching criteria. Unmatched characteristics were similar among the pairs, including serum creatinine variability during the week preceding scanning (67 ± 85% among contrast recipients, 63 ± 62% among others) and clinical risk factors for renal failure. In 29 pairs, pre-scan measured clearances were less than 60 mL/minute/1.73 m2. Following scanning, measured clearance declined by at least 33% in 14 contrast and 19 non-contrast patients (95% confidence interval for contrast associated difference in nephropathy rates -27% to 9%), while a 50% reduction in clearance persisted three days after scanning in three contrast and nine non-contrast patients (95% confidence interval for difference in rates -25% to 2%).ConclusionsAmong established intensive care unit patients declines in glomerular filtration following contrast-enhanced scanning are common, but these changes are far more likely to be attributable to factors other than the contrast exposure itself. The upper bound for the incidence of contrast induced renal injury lasting even three days was 2% in the population studied.

Outcomes in Nonagenarians after Hemiarthroplasty for Femoral Neck Fracture. A Prospective Matched Cohort Study

A prospective cohort of 33 nonagenarians with hemiartroplasty for femoral neck fracture was matched with 33 patients aged between 70 and 89, using preoperative and postoperative data, and the following were studied; epidemiological data, physical dependence, and SF-12 and WOMAC questionnaires. The mortality rate at one year was 24.2%, influenced by the presence of 3 or more comorbidities, dementia, and previous dependence. The perioperative period was the most vulnerable time, and in some cases delaying surgery should be considered to stabilise the patient's medical condition in very elderly patients. Mortality and functional outcomes were worse than in younger patients, but the surgical complication rate was similar. Prognostic factors for a decline in quality of life were dementia and previous dependence.

Childhood appendectomy, tonsillectomy, and risk for premature acute myocardial infarction--a nationwide population-based cohort study

Although inflammation contributes to cardiovascular disease, the associations of appendectomy and tonsillectomy, which remove mucosa-associated lymphoid tissue, with risk of acute myocardial infarction (AMI) are unknown. Our aim was to assess the association between these operations performed in childhood and AMI risk later in life. We conducted a prospective matched cohort study among all Swedish residents born between 1955 and 1970. A national register identified all appendectomies and tonsillectomies. For each patient undergoing appendectomy or tonsillectomy, we randomly selected five controls without the history of the respective operation, matched on sex, age, and county of residence. Participants were followed for fatal and non-fatal AMI for an average of 23.5 years. Because appendiceal and tonsillar tissues have reduced function after adolescence, our primary analyses were restricted to individuals below age 20 at the time of surgery (54 449 appendectomies and 27 284 tonsillectomies). We derived hazard ratios (HRs) from proportional hazard models adjusted for parental occupation and parental history of AMI. Operations before 20 years of age were associated with an increased risk for AMI (417 and 216 events in the appendectomy and tonsillectomy datasets, respectively), with adjusted HRs of 1.33 [95% confidence interval (CI), 1.05-1.70] for appendectomy and 1.44 (95% CI, 1.04-2.01) for tonsillectomy. This association was graded, with the highest risk among those undergoing both procedures, and generally similar among both males and females. Appendectomy and tonsillectomy performed at or above 20 years of age were not associated with the risk of AMI. We found a higher risk of AMI related to surgical removal of the tonsils and appendix before age 20. These results are consistent with the hypothesis that subtle alterations in immune function following these operations may alter the subsequent cardiovascular risk, but further studies are needed to confirm these findings and to explore possible mechanisms.

Androgen deprivation therapy for prostate cancer: not so simple

Androgen deprivation therapy for prostate cancer: not so simple

Transoral Robotic Surgery using the Thulium‐YAG Laser: A Prospective Study

Objective To compare thulium:YAG laser–assisted transoral robotic surgery (TY:TORS) and conventional electrocautery-equipped TORS (EC:TORS) in patients undergoing transoral resection of upper aerodigestive tract malignant neoplasms. Design Prospective matched cohort study. Setting Tertiary academic referral center. Patients Fifteen patients undergoing TY:TORS were matched on the basis of tumor site, clinical T stage, sex, and age with 30 control subjects undergoing EC:TORS. Main Outcome Measures The primary outcome was a comparison between the feasibility of TY:TORS compared with EC:TORS. The secondary outcome was a comparison between the safety and functional outcome of TY:TORS compared with EC:TORS in patients undergoing resection of upper aerodigestive tract malignant neoplasms. Results All the tumors underwent complete excision with negative margins. Estimated blood loss was minimal ( Conclusions Compared with EC:TORS, TY:TORS seems feasible and safe. In addition, TY:TORS resulted in fewer intraoperative pharyngotomies and less postoperative pain than did EC:TORS, which may be because of decreased collateral thermal damage, improved visualization, and finer cutting using the thulium laser.

Effects of caesarean section on maternal health in low risk nulliparous women: a prospective matched cohort study in Shanghai, China.

BackgroundRates of caesarean section are progressively increasing in many parts of the world. As a result of psychosocial factors there has been an increasing tendency for pregnant women without justifiable medical indications for caesarean section to ask for this procedure in China. A critical examination of this issue in relation to maternal outcomes is important. At present there are no clinical trials to help assess the risks and benefits of caesarean section in low risk women. To fill the gap left by trials, this indication-matched cohort study was carried out to examine prospectively the outcomes of caesarean section on women with no absolute obstetric indication compared with similar women who had vaginal delivery.MethodsAn indication-matched cohort study was undertaken to compare maternal outcomes following caesarean section with those undergoing vaginal delivery, in which the two groups were matched for non-absolute indications. 301 nulliparous women with caesarean section were matched successfully with 301 women who delivered vaginally in the Maternal and Children's Hospitals (MCHs) in Shanghai, China. Logistic regression model or binomial regression model was used to estimate the relative risk (RR) directly. Adjusted RRs were calculated adjusting for propensity score and medical indications.ResultsThe incidence of total complications was 2.2 times higher in the caesarean section group during hospitalization post-partum, compared with the vaginal delivery group (RR = 2.2; 95% CI: 1.1-4.4). The risk of haemorrhage from the start of labour until 2 hours post-partum was significantly higher in the caesarean group (RR = 5.6; 95% CI: 1.2-26.9). The risk of chronic abdominal pain was significantly higher for the caesarean section group (RR = 3.6; 95% CI: 1.2-10.9) than for the vaginal delivery group within 12 months post-partum. The two groups had similar incidences of anaemia and complicating infections such as wound complications or urinary tract infection.ConclusionsIn nulliparous women who were at low risk, caesarean section was associated with a higher rate of post-partum morbidity. Those requesting the surgical procedure with no conventional medical indication, should be advised of the potential risks.

Expressive vocabulary of children with hearing loss in the first 2 years of life: impact of early intervention

The aim of this study was to determine the expressive vocabulary of children with hearing loss (HL) enrolled in early intervention (EI) ≤ 3 vs >3 months in the first 24 months and to compare with hearing controls. It was hypothesized that the number of words produced would be higher for children with HL enrolled in EI ≤ 3 vs >3 months. This is a prospective longitudinal matched cohort study. The children with HL produced fewer words than the children with hearing. In addition, children with HL enrolled in EI ≤ 3 months had a larger expressive vocabulary percentile score compared with children with HL enrolled >3 months. Children with mild HL enrolled in EI ≤ 3 months had the greatest growth in vocabulary between 12 to 16 and 18 to 24 months. Although multiple factors are associated with expressive vocabulary growth of children with HL, enrollment in EI ≤ 3 months has sustained beneficial effects on expressive vocabulary at 18 to 24 months.

Declines in physical function from androgen deprivation therapy (ADT) in men with nonmetastatic prostate cancer: A matched cohort study

9526 Background: Although prolonged use of ADT is hypothesized to adversely affect physical function, few studies have examined this relationship longitudinally using objective measures of physical function. Methods: Men age 50+ with non-metastatic prostate cancer (PC) starting continuous ADT were enrolled in this prospective longitudinal matched cohort study. Physical function was assessed with the six-minute walk test (6MWT), grip strength, and the Timed Up and Go (TUG) test, representing endurance, upper extremity strength, and lower extremity strength, respectively. Self-reported physical function was measured with the Medical Outcomes Study SF-36. Assessments were done at baseline, 3 months, 6 months, and 12 months. Two control groups, matched on age, education, and baseline function were also enrolled. One control group had PC but did not receive ADT, and the other group did not have PC. Linear mixed effects regression models were fitted adjusting for baseline covariates. Results: 85 patients on ADT, 86 PC controls, and 86 healthy controls were enrolled. All 3 groups were similar in age (mean age 69.1 y, range 50–87) and physical function (all ANOVA p>0.05). The 6MWT distance improved in both control groups (p=0.05 and 0.05 for PC and healthy controls, respectively) but remained stable in the ADT group (p=0.96)). Grip strength declined in the ADT group (p=0.04), remained stable in the PC control group (p=0.31), and improved in the healthy control group (p=0.008). TUG scores remained stable over time and across groups (p>0.10). SF-36 physical function declined in the ADT group (p<0.001) but increased in both control groups (p<0.001). Negative effects on outcomes were noted within 3–6 months of starting ADT and were larger with older age. Conclusions: Endurance, upper extremity strength, and self-reported physical function are affected within 3–6 months of starting ADT, particularly in older men. Declines persist at 12 months after adjustment for baseline function and covariates. Exercise intervention studies to counteract these losses are warranted. No significant financial relationships to disclose.

Gender as a Moderator of Cognitive and Affective Outcome After Traumatic Brain Injury

Gender as a Moderator of Cognitive and Affective Outcome After Traumatic Brain Injury

Mortality Attributable to Hospital-Acquired Infections Among Surgical Patients

We performed a multicenter prospective matched cohort study to evaluate the mortality attributable to hospital-acquired infections among 12,791 patients admitted to surgical departments. We were able to match 731 patients with 1 or more hospital-acquired infections (ie, case patients) with 731 patients without a hospital-acquired infection (ie, control patients) at a 1:1 ratio. Of the 731 case patients, 42 (5.7%) died; of the 731 control patients, 23 (3.1%) died--a significant difference of 2.6%.

Long-Term Cognitive Outcome of Delirium in Elderly Hip Surgery Patients

Objective: To study the outcome of delirium in elderly hip surgery patients. Design: Prospective matched controlled cohort study. Hip surgery patients (n = 112) aged 70 years and older, who participated in a controlled clinical trial of haloperidol prophylaxis for delirium, were followed for an average of 30 months after discharge. Patients with a diagnosis of dementia or mild cognitive impairment (MCI) were identified using psychiatric interviews. Proportions of patients with dementia/MCI were compared across patients who had postoperative delirium and selected control patients matched for preoperatively assessed risk factors who had not developed delirium during index hospitalization. Other outcomes were mortality rate and rate of institutionalization. Results: During the follow-up period, 54.9% of delirium patients had died compared to 34.1% of the controls (relative risk = 1.6, 95% CI = 1.0–2.6). Dementia or MCI was diagnosed in 77.8% of the surviving patients with postoperative delirium and in 40.9% of control patients (relative risk = 1.9, 95% CI = 1.1–3.3). Half of the patients with delirium were institutionalized at follow-up compared to 28.6% of the controls (relative risk = 1.8, 95% CI = 0.9–3.4). Conclusion: The risk of dementia or MCI at follow-up is almost doubled in elderly hip surgery patients with postoperative delirium compared with at-risk patients without delirium. Delirium may indicate underlying dementia.

Increased carotid intima media thickness and cardiac biomarkers in HIV infected children

To assess carotid intima media thickness (IMT) and cardiac biomarkers in HIV infected children on antiretroviral therapy (ART). This was a single site, cross sectional, controlled observational study. We assessed carotid IMT, homocysteine, high-sensitivity C-reactive protein and myeloperoxidase levels in HIV infected children on stable ART for >or= 6 months. Carotid IMT was reported as internal carotid artery (ICA) and common carotid artery (CCA) thickness; left and right sides were measured separately. Groups were compared using appropriate two-sample tests. Of the 62 subjects enrolled, 31 were HIV positive (50%), 66% were female, and 69% were African-American. Median CD4% was 32% and 26 patients (84%) had HIV-1 RNA< 400 copies/ml. Sixteen patients had been taking protease inhibitors for a median duration of 27 months. None had hypertension or smoked. HIV infected children had higher HOMA-IR, waist-to-hip ratio, cholesterol, triglycerides, myeloperoxidase and lower homocysteine levels. Left and right CCA IMT, and left and right ICA IMT were significantly higher in the HIV infected group. Significant predictors of carotid IMT measurements in uninfected controls were body mass index and homocysteine, but only the duration of ARV therapy was predictive of IMT in the HIV infected group. Higher levels of carotid IMT and some cardiac markers were found in ART treated HIV infected children when compared to matched uninfected controls. These results suggest that HIV infected children receiving ART may be at increased risk of cardiovascular disease.

Bilateral total knee replacement under a single anaesthetic, using a cementless implant is not unsafe

Bilateral knee replacement under single anaesthetic is not a common procedure. There is a general agreement that this is associated with greater morbidity and mortality. However, there is a suggestion in literature that using a cementless implant could reduce this risk. We wanted to make a prospective comparison of safety and clinical results, between unilateral and bilateral cementless knee replacements performed under a single anaesthetic. A prospective non-randomised matched cohort study on 87 consecutive patients who had bilateral simultaneous/sequential knee replacement and 174 consecutive patients who had unilateral knee replacement between the period of 1997 and 2002 were included in this study. All patients had a cementless mobile-bearing implant. All patients had an independent objective assessment at follow-up. There was no significant difference between the two groups in terms of age, sex, primary diagnosis (osteoarthritis or rheumatoid arthritis), co-morbidity, ASA grade, average range of motion and average American knee society score and post-operative surgical complications. There was one early death in the bilateral group, and three in the unilateral group. The clinical results of bilateral group were as good as the unilateral group. Our study showed that in terms of postoperative medical and surgical complications, bilateral simultaneous/sequential knee replacement using a cementless mobile-bearing implant is as safe as a unilateral knee replacement. With careful patient selection, bilateral knee replacement under a single anaesthetic would be a suitable option for patients who present with bilateral symptomatic arthritis of the knee.

Outcome of Older Critically lIl Patients: A Matched Cohort Study

Background: Admission of older patients to intensive care units is a controversial issue. Objective: To estimate age-associated mortality of critically ill patients. Methods: A prospective matched cohort study in the Medical-Surgical Intensive Care Unit of a tertiary hospital was conducted. We included 100 consecutive patients older than 70 years admitted to the intensive care unit (cases) and 100 patients younger than 70 years (controls). The matching criterion was the severity of illness at admission to the intensive care unit as estimated by the simplified acute physiological score (SAPS II) without including age in its calculation. Results: Mortality in the intensive care unit was higher, but not statistically significant, in the older group: 26% vs. 19% (p = 0.23). Patients older than 70 years had a longer duration of mechanical ventilation (median 7 vs. 3 days) and longer stay in the intensive care unit (median 8 vs. 5 days). There were no differences in organ dysfunctions, except for a higher incidence of respiratory failure in the older group (p < 0.001). The use of invasive procedures was similar in both groups. There were more orders for the withholding/withdrawal of treatment in patients older than 70 years (9 vs. 3%, p = 0.07). Conclusion: In our study, age was not related with a significant higher mortality. In the older patients included in our study the survival was greater than 70% with a similar resource utilization except for a longer stay in the intensive care unit.

Coronary artery bypass grafting and sensorineural hearing loss, a cohort study.

BackgroundSudden sensorineural hearing loss is routinely encountered by the otologist. The etiology is varied and often identifiable. One of the relatively less frequent causes is surgery. Apart from being an established entity with otological surgeries, sensorineural hearing loss has also been known to occur after non-otological procedures under general anesthesia. Commonest amongst these procedures is cardiopulmonary bypass, an association that has long been recognized. However, despite the proposition of diverse hypotheses in the past, the pathophysiology remains unclear.MethodsThe study is a prospective matched cohort study that will be carried out in Aga Khan University Hospital, Karachi, Pakistan. Participants among exposed would include all those patients who would be undergoing coronary artery bypass surgery in the hospital who fall under the criteria for inclusion. Unexposed group would comprise of patients undergoing a non-bypass procedure of similar duration under the same type of anesthesia who meet the selection criteria. Both these groups will undergo audiometric testing at our hospital on three different occasions during the course of this study. Initially before the procedure to test the baseline hearing capacity; then one week after the procedure to assess any changes in hearing ability following the surgery; and finally a third audiogram at six weeks follow-up to assess further changes in any hearing deficits noted during the second phase of testing. Certain variables including the subjects' demographics and those concerning the procedure itself will be noted and used later for risk factors analysis. A detailed past medical and surgical history will also be obtained. Data analysis would include calculation of relative risk and significance of the results, by running the chi-square test. Other statistical tests like Fisher exact test may then be employed to facilitate data interpretation. Continuous scale may then be employed and multivariate linear regression used.DiscussionThis study is planned to obtain a better understanding of the correlation between sudden sensorineural hearing loss and cardiopulmonary bypass. Being the first major cohort trial in this line of investigation, the project is designed to identify the existence of any significant relationship between cardiopulmonary bypass and sensorineural hearing deficit.

Carotid artery intima–media thickness and HIV infection: traditional risk factors overshadow impact of protease inhibitor exposure

The impact of HIV infection and exposure to antiretroviral therapy on the development of subclinical atherosclerosis is incompletely understood. To compare intima-media thickness (IMT) of the carotid artery between HIV-infected subjects receiving protease inhibitor-containing regimens and subjects not receiving these regimens and to compare differences in the IMT of the carotid artery between HIV-infected subjects and HIV-uninfected subjects. A prospective matched cohort study in university-based outpatient clinics. Groups of three individuals (triads) matched on the following characteristics were enrolled: age, sex, race/ethnicity, smoking status, blood pressure and menopausal status. Group 1, HIV-infected subjects with continuous use of protease inhibitor (PI) therapy for > or = 2 years; group 2, HIV-infected subjects without prior PI use; and group 3: HIV-uninfected. Ultrasonographers at six sites sent standardized ultrasound images to a central reading site for carotid IMT measurements. Carotid IMT was compared within the HIV-infected groups (1 and 2) and between the HIV-infected and uninfected groups in a matched analysis. One hundred and thirty-four individuals were enrolled in 45 triads. The median IMT in groups 1, 2 and 3 was 0.690, 0.712 and 0.698 mm, respectively. There were no statistically significant differences in IMT between groups 1 and 2, or in the combined HIV groups compared with the HIV uninfected group. Significant predictors of carotid IMT in a multivariate model included high-density lipoprotein (HDL) cholesterol, the interaction of HDL cholesterol and triglycerides, age and body mass index. We found no association between PI inhibitor exposure or HIV infection and carotid IMT.

The Effects of Long-term Heparin Therapy During Pregnancy on Bone Density

We performed a prospective matched cohort study to investigate the effects of long-term (> 1 month) heparin therapy on lumbar spine bone density. Twenty-five women who received heparin during pregnancy, and 25 matched controls underwent dual photon absorptiometry of the lumbar spine in the post-partum period. Zero of 25 heparin-treated patients developed fractures. Heparin-treated patients had a 0.082 g/cm2 lower bone density compared to untreated controls, which is clinically and statistically significant (p = 0.0077). There were 6 matched pairs in which only the heparin-treated patient had a bone density below 1.0 g/cm2, compared to only one pair in which only the control patient had a bone density below this level (p = 0.089). The correlation coefficients of the difference in bone density in each matched pair, and the duration of heparin therapy, the mean daily dose, and the total dose of heparin were 0.042, - 0.015, and 0.021, respectively; none of these values is statistically significant. We conclude: 1) long-term heparin therapy was associated with a significant reduction in bone density, although fractures are uncommon, 2) there was no significant correlation between lumbar bone density and the dose or duration of heparin.