Arief Lalmohamed

Risk of fracture after bariatric surgery in the United Kingdom: population based, retrospective cohort study

Objectives To estimate fracture risk in patients receiving bariatric surgery versus matched controls. Design Population based, retrospective cohort study. Setting Use of records from the United Kingdom General Practice Research Database, now known as the Clinical Practice Research Datalink (from January 1987 to December 2010). Participants Patients with a body mass index of at least 30, with a record of bariatric surgery (n=2079), and matched controls without a record (n=10 442). Each bariatric surgery patient was matched to up to six controls by age, sex, practice, year, and body mass index. Patients were followed from the date of bariatric surgery for the occurrence of any fracture. We used time dependent Cox regression to calculate relative rates of fracture, adjusted for disease and previous drug treatment, and time-interaction terms to evaluate fracture timing patterns. Main outcome measure Relative rates of any, osteoporotic, and non-osteoporotic fractures. Results Mean follow-up time was 2.2 years. Overall, there was no significantly increased risk of fracture in patients who underwent bariatric surgery, compared with controls (8.8 v 8.2 per 1000 person years; adjusted relative risk 0.89, 95% confidence interval 0.60 to 1.33). Bariatric surgery also did not affect risk of osteoporotic and non-osteoporotic fractures. However, we saw a trend towards an increased fracture risk after three to five years following surgery, as well as in patients who had a greater decrease in body mass index after surgery, but this was not significant. Conclusion Bariatric surgery does not have a significant effect on the risk of fracture. For the first few years after surgery, these results are reassuring for patients undergoing such operations, but do not exclude a more protracted adverse influence on skeletal health in the longer term.

Risk of Hip/Femur Fracture After Stroke: A Population-Based Case-Control Study

Background and Purpose— Stroke increases the risk of hip/femur fracture, as seen in several studies, although the time course of this increased risk remains unclear. Therefore, our purpose is to evaluate this risk and investigate the time course of any elevated risk. Methods— We conducted a case-control study using the Dutch PHARMO Record Linkage System database. Cases (n=6763) were patients with a first hip/femur fracture; controls were matched by age, sex, and region. Odds ratio (OR) for the risk of hip/femur fracture was derived using conditional logistic regression analysis, adjusted for disease and drug history. Results— An increased risk of hip/femur fracture was observed in patients who experienced a stroke at any time before the index date (adjusted OR, 1.96; 95% CI, 1.65–2.33). The fracture risk was highest among patients who sustained a stroke within 3 months before the index date (adjusted OR, 3.35; 95% CI, 1.87–5.97) and among female patients (adjusted OR, 2.12; 95% CI, 1.73–2.59). The risk further increased among patients younger than 71 years (adjusted OR, 5.12; 95% CI, 3.00–8.75). Patients who had experienced a hemorrhagic stroke tended to be at a higher hip/femur fracture risk compared with those who had experienced an ischemic stroke. Conclusions— Stroke is associated with a 2.0-fold increase in the risk of hip/femur fracture. The risk was highest among patients younger than 71 years, females, and those whose stroke was more recent. Fall prevention programs, bone mineral density measurements, and use of bisphosphonates may be necessary to reduce the occurrence of hip/femur fractures during and after stroke rehabilitation.

Causes of death in patients with multiple sclerosis and matched referent subjects: a population-based cohort study

Background and purpose:  Multiple sclerosis (MS) has been associated with increased mortality rates. However, influence of lifestyle parameters remains unknown, and inconsistencies exist regarding findings for causes of death.

Timing of Acute Myocardial Infarction in Patients Undergoing Total Hip or Knee Replacement A Nationwide Cohort Study

BACKGROUND Limited evidence suggests that the risk of acute myocardial infarction (AMI) may be increased shortly after total hip replacement (THR) and total knee replacement (TKR) surgery. However, risk of AMI in these patients has not been compared against matched controls who have not undergone surgery. The objective of this study was to evaluate the timing of AMI in patients undergoing THR or TKR surgery compared with matched controls. METHODS Retrospective, nationwide cohort study within the Danish national registries. All patients who underwent a primary THR or TKR (n = 95,227) surgery from January 1, 1998, through December 31, 2007, were selected and matched to 3 controls (no THR or TKR) by age, sex, and geographic region. All study participants were followed up for AMI, and disease- and medication history-adjusted hazard ratios (HRs) were calculated. RESULTS During the first 2 postoperative weeks, the risk of AMI was substantially increased in THR patients compared with controls (adjusted HR, 25.5; 95% CI, 17.1-37.9). The risk remained elevated for 2 to 6 weeks after surgery (adjusted HR, 5.05; 95% CI, 3.58-7.13) and then decreased to baseline levels. For TKR patients, AMI risk was also increased during the first 2 weeks (adjusted HR, 30.9; 95% CI, 11.1-85.5) but did not differ from controls after the first 2 weeks. The absolute 6-week risk of AMI was 0.51% in THR patients and 0.21% in TKR patients. CONCLUSIONS Risk of AMI is substantially increased in the first 2 weeks after THR (25-fold) and TKR (31-fold) surgery compared with controls. Risk assessment of AMI should be considered during the first 6 weeks after THR surgery and during the first 2 weeks after TKR surgery.

HIV infection and its association with an excess risk of clinical fractures: a nationwide case-control study.

Background:Different studies have reported an association between HIV infection, antiretroviral therapies, and impaired bone metabolism, but data on their impact on fracture risk are scarce. We studied the association between a clinical diagnosis of HIV infection and fracture risk. Methods:We conducted a case–control study using data from the Danish National Health Service registries, including 124,655 fracture cases and 373,962 age- and gender-matched controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression. Results:A total of 50 (0.40/1000) patients in the fracture group and 52 (0.14/1000) controls had an HIV diagnosis. The risk of any fracture was thus significantly increased among HIV-infected patients (age- and gender-matched OR = 2.89, 95% CI: 1.99 to 4.18). Similarly, significant increases in the risk of hip (OR = 8.99, 95% CI: 1.39 to 58.0), forearm (OR = 3.50, 95% CI: 1.26 to 9.72), and spine fractures (OR = 9.00, 95% CI: 1.39 to 58.1) were observed. Conclusions:HIV infection is associated with an almost 3-fold increase in fracture risk compared with that of age- and gender-matched uninfected patients. HIV patients are also at an almost 9-fold higher risk of hip fracture.

Risk of Lactic Acidosis or Elevated Lactate Concentrations in Metformin Users With Renal Impairment: A Population-Based Cohort Study

OBJECTIVE The objective of this study was to determine whether treatment with metformin in patients with renal impairment is associated with a higher risk of lactic acidosis or elevated lactate concentrations compared with users of a noninsulin antidiabetic drug (NIAD) who had never used metformin. RESEARCH DESIGN AND METHODS A cohort of 223,968 metformin users and 34,571 diabetic patients who had never used metformin were identified from the Clinical Practice Research Datalink (CPRD).The primary outcome was defined as either a CPRD READ code lactic acidosis or a record of a plasma lactate concentration >5 mmol/L. The associations between renal impairment, dose of metformin, and the risk of lactic acidosis or elevated lactate concentrations were determined with time-dependent Cox models and expressed as hazard ratios (HRs). RESULTS The crude incidence of lactic acidosis or elevated lactate concentrations in current metformin users was 7.4 per 100,000 person-years (vs. 2.2 per 100,000 person-years in nonusers). Compared with nonusers, risk of lactic acidosis or elevated lactate concentrations in current metformin users was significantly associated with a renal function <60 mL/min/1.73 m2 (adjusted HR 6.37 [95% CI 1.48–27.5]). The increased risk among patients with impaired renal function was further increased in users of ≥730 g of metformin in the preceding year (adjusted HR 11.8 [95% CI 2.27–61.5]) and in users of a recent high daily dose (>2 g) of metformin (adjusted HR 13.0 [95% CI 2.36–72.0]). CONCLUSIONS Our study is consistent with current recommendations that the renal function of metformin users should be adequately monitored and that the dose of metformin should be adjusted, if necessary, if renal function falls below 60 mL/min/1.73 m2.

Use of dipeptidyl peptidase-4 inhibitors for type 2 diabetes mellitus and risk of fracture

INTRODUCTION Although patients with type 2 diabetes mellitus have an increased bone mineral density as compared to healthy patients, their risk of fracture is elevated. Incretins, new anti-diabetic drugs, may have a protective effect on bone mineral density. However, data on the effect of incretins on fracture risk are limited. Therefore the aim of this study was to investigate the association between the use of DPP4-I and the risk of fracture. METHODS A retrospective population based cohort study, using data from the Clinical Practice Research Datalink (CPRD) database (2007-2012), was conducted. Patients (N=216,816) with at least one prescription for a non-insulin anti-diabetic drug (NIAD), aged 18+ during data collection, were matched to one control patient. Cox proportional hazards models were used to estimate the hazard ratio of any fracture in DPP4 inhibitor (DPP4-I) users versus controls and versus other NIAD patients. Time-dependent adjustments were made for age, sex, life style, comorbidity and drug use. RESULTS The actual duration of DPP4-I use was 1.3years. There was no different risk of fracture comparing current DPP4-I users to controls (adjusted hazard ratio (adj. HR) 0.89, 95% confidence interval (CI) 0.71-1.13). There was also no increased risk comparing current DPP4-I users to other NIAD users, adj. HR 1.03 (95% CI 0.92-1.15). CONCLUSIONS DPP4-I use was not associated with fracture risk compared to controls and to other NIAD users. However, the duration of DPP4-I use in our database might have been too short to show an association with fracture risk.

Remission of Type 2 Diabetes Mellitus in Patients After Different Types of Bariatric Surgery: A Population-Based Cohort Study in the United Kingdom.

IMPORTANCE To our knowledge, an observational study on the remission of type 2 diabetes mellitus (T2DM) after different types of bariatric surgery based on data from general practice has not been carried out. OBJECTIVE To assess the effect of different types of bariatric surgery in patients with T2DM on diabetes remission compared with matched control patients, and the effect of the type of bariatric surgery on improvement of glycemic control and related clinical parameters. DESIGN, SETTING, AND PARTICIPANTS A retrospective cohort study conducted from May 2013 to May 2014 within the Clinical Practice Research Datalink involving 2978 patients with a record of bariatric surgery (2005-2012) and a body mass index (calculated as weight in kilograms divided by height in meters squared) of 35 or greater. We identified 569 patients with T2DM and matched them to 1881 patients with diabetes without bariatric surgery. Data on the use of medication and laboratory results were evaluated. EXPOSURES Bariatric surgery, stratified by type of surgery (gastric banding, Roux-en-Y gastric bypass, sleeve gastrectomy, or other/unknown). MAIN OUTCOMES AND MEASURES Remission of T2DM (complete discontinuation of glycemic therapy, accompanied with a subsequently recorded hemoglobin A1c level<6.0%). RESULTS Among patients undergoing bariatric surgery, we found a prevalence of 19.1% for T2DM. Per 1000 person-years, 94.5 diabetes mellitus remissions were found in patients who underwent bariatric surgery compared with 4.9 diabetes mellitus remissions in matched control patients. Patients with diabetes who underwent bariatric surgery had an 18-fold increased chance for T2DM remission (adjusted relative rate [RR], 17.8; 95% CI, 11.2-28.4) compared with matched control patients. The greatest effect size was observed for gastric bypass (adjusted RR, 43.1; 95% CI, 19.7-94.5), followed by sleeve gastrectomy (adjusted RR, 16.6; 95% CI, 4.7-58.4) and gastric banding (adjusted RR, 6.9; 95% CI, 3.1-15.2). Body mass index and triglyceride, blood glucose, and hemoglobin A1c levels sharply decreased during the first 2 years after bariatric surgery. CONCLUSIONS AND RELEVANCE Population-based data show that bariatric surgery strongly increases the chance for remission of T2DM. Gastric bypass and sleeve gastrectomy have a greater effect than gastric banding. Although the risks and possible adverse effects of surgery should be weighed against its benefits, bariatric surgery and, in particular, gastric bypass or sleeve gastrectomy may be considered as new treatment options for T2DM.

Changes in mortality patterns following total hip or knee arthroplasty over the past two decades: A nationwide cohort study

Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are effective procedures for patients with moderate‐to‐severe osteoarthritis. Mortality rates after THA and TKA may have changed because of new surgical techniques, improvement of peri‐ and postoperative care, and performance of surgery in older patients having multiple comorbidities. However, data on secular mortality trends are scarce. We undertook this study to evaluate mortality patterns between 1989 and 2007 in patients undergoing elective THA and TKA.

Timing of Stroke in Patients Undergoing Total Hip Replacement and Matched Controls: A Nationwide Cohort Study

Background and Purpose— Stroke is a potentially fatal complication of total hip replacements (THR). However, timing of stroke in THR patients compared with matched controls and influence of drug use remain unknown. The objective of this study was to determine timing of stroke in patients with THR compared with matched control subjects. Methods— A nationwide cohort study was conducted within the Danish registers (1998–2007). Included patients were those with a primary THR in the study period (n=66 583) and were matched by age, sex, and region to three referent subjects without THR or total knee replacements. Time-dependent Cox models were used to derive hazard ratios and were adjusted for disease history and drug use. Results— A 4.7-fold increased risk of ischemic stroke (adjusted hazard ratio, 4.69; 95% CI, 3.12–7.06), and a 4.4-fold increased risk of hemorrhagic stroke (adjusted hazard ratio, 4.40; 95% CI, 2.01–9.62) were found within 2 weeks following THR, compared with matched controls. The risk remained elevated during the first 6 postoperative weeks for ischemic stroke, and the first 12 weeks for hemorrhagic stroke. Outpatient antiplatelet drug use lowered the 6-week hazard ratios for ischemic stroke by 70%, although not affecting risk of hemorrhagic stroke. Conclusions— This study shows, that THR patients have a 4.7-fold increased risk of ischemic stroke, and a 4.4-fold increased risk of hemorrhagic stroke during the first 2 weeks postsurgery. Risk assessment of stroke in individual patients undergoing THR (ie, evaluate other risk factors for stroke) should be considered during the first 6 to 12 weeks.