Anjie Huang

Cardiovascular disease in kidney donors: matched cohort study

Objective To determine whether people who donate a kidney have an increased risk of cardiovascular disease. Design Retrospective population based matched cohort study. Participants All people who were carefully selected to become a living kidney donor in the province of Ontario, Canada, between 1992 and 2009. The information in donor charts was manually reviewed and linked to provincial healthcare databases. Matched non-donors were selected from the healthiest segment of the general population. A total of 2028 donors and 20 280 matched non-donors were followed for a median of 6.5 years (maximum 17.7 years). Median age was 43 at the time of donation (interquartile range 34-50) and 50 at the time of follow-up (42-58). Main outcome measures The primary outcome was a composite of time to death or first major cardiovascular event. The secondary outcome was time to first major cardiovascular event censored for death. Results The risk of the primary outcome of death and major cardiovascular events was lower in donors than in non-donors (2.8 v 4.1 events per 1000 person years; hazard ratio 0.66, 95% confidence interval 0.48 to 0.90). The risk of major cardiovascular events censored for death was no different in donors than in non-donors (1.7 v 2.0 events per 1000 person years; 0.85, 0.57 to 1.27). Results were similar in all sensitivity analyses. Older age and lower income were associated with a higher risk of death and major cardiovascular events in both donors and non-donors when each group was analysed separately. Conclusions The risk of major cardiovascular events in donors is no higher in the first decade after kidney donation compared with a similarly healthy segment of the general population. While we will continue to follow people in this study, these interim results add to the evidence base supporting the safety of the practice among carefully selected donors.

Accepting Kidneys from Older Living Donors: Impact on Transplant Recipient Outcomes

Older living kidney donors are regularly accepted. Better knowledge of recipient outcomes is needed to inform this practice. This retrospective cohort study observed kidney allograft recipients from Ontario, Canada between January 2000 and March 2008. Donors to these recipients were older living (≥60 years), younger living, or standard criteria deceased (SCD). Review of medical records and electronic healthcare data were used to perform survival analysis. Recipients received 73 older living, 1187 younger living and 1400 SCD kidneys. Recipients of older living kidneys were older than recipients of younger living kidneys. Baseline glomerular filtration rate (eGFR) of older kidneys was 13 mL/min per 1.73 m2 lower than younger kidneys. Median follow‐up time was 4 years. The primary outcome of total graft loss was not significantly different between older and younger living kidney recipients [adjusted hazard ratio, HR (95%CI): 1.56 (0.98–2.49)]. This hazard ratio was not proportional and increased with time. Associations were not modified by recipient age or donor eGFR. There was no significant difference in total graft loss comparing older living to SCD kidney recipients [HR: 1.29 (0.80–2.08)]. In light of an observed trend towards potential differences beyond 4 years, uncertainty remains, and extended follow‐up of this and other cohorts is warranted.

Fracture Risk in Living Kidney Donors: A Matched Cohort Study

BACKGROUND Chronic kidney disease increases the risk of bone fragility fractures (osteoporotic fractures). Living kidney donors lose 50% of their renal mass and show changes in calcium homeostasis. We studied whether living kidney donation increases the risk of fragility fracture. DESIGN Retrospective matched-cohort study. SETTING & PARTICIPANTS We reviewed the medical charts of all 2,015 adults in Ontario, Canada, who donated a kidney between 1992 and 2009 (surgeries performed across 5 transplant programs). We linked this information to health care databases and randomly selected 20,150 matched nondonors from the healthiest portion of the general population. Median age was 43 (95% CI, 24-50) years at study enrollment. Donors and nondonors were then followed up for a median of 6.6 years and a maximum of 17.7 years. PREDICTOR Living donor nephrectomy. OUTCOMES The primary outcome was lower- and upper-extremity fragility fractures. Individuals who reached 66 years or older in follow-up had bisphosphonate prescriptions recorded. RESULTS The rate of fragility fracture was no higher in donors compared with nondonors (16.4 vs 18.7 events/10,000 person-years; rate ratio, 0.88; 95% CI, 0.58-1.32). Results were similar in multiple additional analyses. There was little difference in the proportion of older adults in follow-up who received a bisphosphonate prescription (17.1% vs 15.2%; P = 0.4). LIMITATIONS These are interim results. Ongoing surveillance of this and other donor cohorts is warranted to be sure an association does not manifest with longer follow-up. CONCLUSIONS To date, there is no evidence of increased fragility fracture risk in living kidney donors. Our results meet an information need and are reassuring for the safety of the practice.

Acute dialysis risk in living kidney donors

It is crucial to carefully screen donors and essential to resist compromises. If this is respected the survival, the co-morbidity, ESRD or even acute renal failure, as shown by Lam et al. in the current issue of this journal, appear to be similar to those in the general population.

Risk of kidney stones with surgical intervention in living kidney donors.

A kidney stone in a person with a solitary kidney requires urgent attention, which may result in surgical and/or hospital attention. We conducted a matched retrospective cohort study to determine if living kidney donors compared to healthy nondonors have a higher risk of: (i) kidney stones with surgical intervention, and (ii) hospital encounters for kidney stones. We reviewed all predonation charts for living kidney donations from 1992 to 2009 at five major transplant centers in Ontario, Canada, and linked this information to healthcare databases. We selected nondonors from the healthiest segment of the general population and matched 10 nondonors to every donor. Of the 2019 donors and 20 190 nondonors, none had evidence of kidney stones prior to cohort entry. Median follow‐up time was 8.4 years (maximum 19.7 years; loss to follow‐up <7%). There was no difference in the rate of kidney stones with surgical intervention in donors compared to nondonors (8.3 vs. 9.7 events/10 000 person‐years; rate ratio 0.85; 95% confidence interval [CI] 0.47–1.53). Similarly there was no difference in the rate of hospital encounters for kidney stones (12.1 vs. 16.1 events/10 000 person‐years; rate ratio 0.75; 95% CI 0.45–1.24). These interim results are reassuring for the safety of living kidney donation.

Risk of serious gastrointestinal bleeding in living kidney donors

Individuals with moderate‐to‐severe reduced renal function have greater risk of gastrointestinal bleeding than those with normal renal function. We conducted a retrospective matched cohort study to assess whether living kidney donors share a similar risk. We reviewed pre‐donation charts for living kidney donations from 1992 to 2009 in Ontario, Canada, and linked this information to healthcare databases. We selected healthy non‐donors from the general population and matched ten non‐donors to every donor. Of the 2009 donors and 20 090 matched non‐donors, none had evidence of gastrointestinal bleeding prior to cohort entry. The cohort was followed for a median of 8.4 yr (maximum 19.7 yr; loss to follow‐up <7%). There was no significant difference in the rate of hospitalization with gastrointestinal bleeding in donors compared to non‐donors (18.5 vs. 14.9 events per 10 000 person‐years; rate ratio 1.24; 95% confidence interval [CI] 0.85–1.81). Similar results were obtained when we assessed the time to first hospitalization with gastrointestinal bleeding (hazard ratio 1.25, 95% CI 0.87–1.79). In conclusion, we found living kidney donation was not associated with a higher risk of hospitalization with gastrointestinal bleeding. These results are reassuring for the safety of the practice.

Living kidney donor estimated glomerular filtration rate and recipient graft survival

BACKGROUND Kidney transplants from living donors with an estimated glomerular filtration rate (eGFR) < 80 mL/min per 1.73 m(2) may be at risk for increased graft loss compared with a recipient who receives a kidney from a living donor with a higher eGFR. METHODS This retrospective cohort study considered 2057 living kidney donors and their recipients from July 1993 to March 2010 at five centres in Ontario, Canada, and linked them to population-based, universal healthcare databases. Recipients were divided into five groups based on their donors baseline eGFR. The median (inter-quartile range) for the lowest eGFR group was 73 (68-77) mL/min per 1.73 m(2). Subjects were followed for a median of 6 years (IQR: 3-10 years). RESULTS There was no significant difference in the adjusted hazard ratio (HR) for graft loss when comparing recipients in each eGFR category to the referent group (≥110 mL/min per 1.73 m(2)). The adjusted HRs (95% CI) from the lowest (<80 mL/min per 1.73 m(2)) to highest (100-109.9 mL/min per 1.73 m(2)) eGFR categories were 1.27 (0.84-1.92), 1.43 (0.96-2.14), 1.23 (0.86-1.77) and 1.23 (0.85-1.77), respectively. Similar results were observed when dichotomizing the baseline donor eGFR using a cut-point of 80 mL/min per 1.73 m(2)-adjusted HR 1.01 [95% confidence interval (95% CI) (0.76-1.44)]. CONCLUSIONS Further research in this setting should clarify whether additional tests (i.e. measured GFR) should be performed in potential donors whose eGFR is considered borderline, whether eGFR values should be standardized to body surface area, and the outcomes for donors after nephrectomy.

Cardiovascular disease after Escherichia coli O157:H7 gastroenteritis

Background: Escherichia coli O157:H7 is one cause of acute bacterial gastroenteritis, which can be devastating in outbreak situations. We studied the risk of cardiovascular disease following such an outbreak in Walkerton, Ontario, in May 2000. Methods: In this community-based cohort study, we linked data from the Walkerton Health Study (2002–2008) to Ontario’s large healthcare databases. We included 4 groups of adults: 3 groups of Walkerton participants (153 with severe gastroenteritis, 414 with mild gastroenteritis, 331 with no gastroenteritis) and a group of 11 263 residents from the surrounding communities that were unaffected by the outbreak. The primary outcome was a composite of death or first major cardiovascular event (admission to hospital for acute myocardial infarction, stroke or congestive heart failure, or evidence of associated procedures). The secondary outcome was first major cardiovascular event censored for death. Adults were followed for an average of 7.4 years. Results: During the study period, 1174 adults (9.7%) died or experienced a major cardiovascular event. Compared with residents of the surrounding communities, the risk of death or cardiovascular event was not elevated among Walkerton participants with severe or mild gastroenteritis (hazard ratio [HR] for severe gastroenteritis 0.74, 95% confidence interval [CI] 0.38–1.43, mild gastroenteritis HR 0.64, 95% CI 0.42–0.98). Compared with Walkerton participants who had no gastroenteritis, risk of death or cardiovascular event was not elevated among participants with severe or mild gastroenteritis. Interpretation: There was no increase in the risk of cardiovascular disease in the decade following acute infection during a major E. coli O157:H7 outbreak.

Association of Overlapping Surgery With Increased Risk for Complications Following Hip Surgery: A Population-Based, Matched Cohort Study

Importance Overlapping surgery, also known as double-booking, refers to a controversial practice in which a single attending surgeon supervises 2 or more operations, in different operating rooms, at the same time. Objective To determine if overlapping surgery is associated with greater risk for complications following surgical treatment for hip fracture and arthritis. Design, Setting, and Participants This was a retrospective population-based cohort study in Ontario, Canada (population, 13.6 million), for the years 2009 to 2014. There was 1 year of follow-up. This study encompassed 2 large cohorts. The “hip fracture” cohort captured all persons older than 60 years who underwent surgery for a hip fracture during the study period. The “total hip arthroplasty” (THA) cohort captured all primary elective THA recipients for arthritis during the study period. We matched overlapping and nonoverlapping hip fractures by patient age, patient sex, surgical procedure (for the hip fracture cohort), primary surgeon, and hospital. Exposures Procedures were identified as overlapping if they overlapped with another surgical procedure performed by the same primary attending surgeon by more than 30 minutes. Main Outcomes and Measures Complication (infection, revision, dislocation) within 1 year. Results There were 38 008 hip fractures, and of those, 960 (2.5%) were overlapping (mean age of patients, 66 years [interquartile range, 57-74 years]; 503 [52.4%] were female). There were 52 869 THAs and of those, 1560 (3.0%) overlapping (mean age, 84 years [interquartile range, 77-89 years]; 1293 [82.9%] were female). After matching, overlapping hip fracture procedures had a greater risk for a complication (hazard ratio [HR], 1.85; 95% CI, 1.27-2.71; P = .001), as did overlapping THA procedures (HR, 1.79; 95% CI, 1.02-3.14; P = .04). Among overlapping hip fracture operations, increasing duration of operative overlap was associated with increasing risk for complications (adjusted odds ratio, 1.07 per 10-minute increase in overlap; P = .009). Conclusions and Relevance Overlapping surgery was relatively rare but was associated with an increased risk for surgical complications. Furthermore, increasing duration of operative overlap was associated with an increasing risk for complications. These findings support the notion that overlapping provision of surgery should be part of the informed consent process.

Hypertension in pregnancy after Escherichia coli O157:H7 gastroenteritis: a cohort study

Background. Escherichia coli O157:H7 is a common cause of bacterial gastroenteritis and may increase the risk of hypertension. We studied the risk of hypertension in pregnancy following a large E. coli O157:H7 outbreak that occurred in Walkerton, Canada, in the year 2000. Methods: We linked data collected from Walkerton residents to provincial healthcare databases. We studied the pregnancies of three groups of women: two groups from Walkerton (those with and without acute gastroenteritis during outbreak) and a third group from neighboring rural communities unaffected by the outbreak. The primary outcome was a composite of gestational hypertension or preeclampsia. Secondary outcomes were gestational hypertension and preeclampsia examined separately. Results: The median time to pregnancy after cohort entry was five years. The composite outcome was not significantly higher among women with gastroenteritis during the outbreak compared with residents of neighboring communities (8 of 117 (6.8%) versus 96 of 2166 (4.4%) pregnancies, respectively; adjusted relative risk 1.5 (95% confidence interval (CI) 0.8 to 3.2)). When examined separately the risk of preeclampsia was significantly higher among women with gastroenteritis (4 of 117 (3.4%) versus 17 of 2166 (0.8%) pregnancies; adjusted relative risk 3.8 (95% CI 1.3 to 11.6)). However, the risk of preeclampsia was lower than expected in the referent group and overall there were a small number of events in all the groups. Conclusion: There was no significant association between E. coli O157:H7 gastroenteritis and our primary assessment of hypertension in pregnancy.