Hospitalizations for aplastic anemia and agranulocytosis in Saskatchewan: incidence and associations with antecedent prescription drug use

Agranulocytosis Associated With Use of Sulfamethoxazole/Trimethoprim in a Healthy Adult

Purpose: A case of sulfamethoxazole/trimethoprim-induced agranulocytosis is reported. Summary: A 53-year-old healthy male presented to the emergency room with a fever of 102.7°F and was found to have a white blood cell (WBC) count of 0.6 × 103 cells/μL with an absolute neutrophil count (ANC) of 0.0 x 103 cells/μL. He had recently completed a 10-day course of sulfamethoxazole/trimethoprim for left lower extremity cellulitis. During admission, a bone marrow biopsy was performed which was not concerning for malignancy and no cause for the agranulocytosis other than the sulfamethoxazole/trimethoprim was identified. The agranulocytosis resolved after 6 days of hospitalization with a WBC count of 8.9 × 103 cells/μL and an ANC of 4.1 x 103cells/μL on the day of discharge. Conclusion: A 53-year-old male developed agranulocytosis after 10 days of sulfamethoxazole/trimethoprim therapy for the treatment of a skin and soft tissue infection. His neutropenia resolved after sulfamethoxazole/trimethoprim discontinuation.

Antipsychotic drug-induced neutropenia: results from the AMSP drug surveillance program between 1993 and 2016

Neutropenia and agranulocytosis (N&A) are relatively rare, but potentially fatal adverse drug reactions (ADR). This study presents cases of N&A related to one or more antipsychotic drugs (APDs) in psychiatric inpatients. Data on APD utilization and reports of N&A caused by APDs were analyzed by using data from an observational pharmacovigilance program in German-speaking countries-Arzneimittelsicherheit in der Psychiatrie (AMSP)-from 1993 to 2016. 333,175 psychiatric inpatients were treated with APDs for schizophrenia and other indications during the observation period. A total of 124 cases of APD-induced N&A were documented, 48 of which fulfilled the criteria for agranulocytosis, corresponding to a rate of 0.37, respectively, 0.14 in 1000 inpatients treated with APDs. Neutropenia was more often detected in women, whereas there was no difference regarding sex in cases of agranulocytosis. Clozapine had the highest relative risk for inducing N&A and was imputed alone as a probable cause of N&A in 60 cases (1.57‰ of all patients exposed). Perazine showed the second highest relative risk with 8 cases and an incidence 0.52‰, followed by quetiapine (15 cases resp. 0.23‰ of all patients exposed) and olanzapine (7 cases; 0.13‰ of all patients exposed). N&A most often occurred during the first 3 months of treatment. Overall N&A are severe and potentially fatal complications that can occur during treatment with APDs. The results from this study largely agree with the currently available literature, highlighting the positive effects of alertness and established appropriate monitoring.

Bioisosteric Modification of To042: Synthesis and Evaluation of Promising Use-Dependent Inhibitors of Voltage-Gated Sodium Channels

Three analogues of To042, a tocainide-related lead compound recently reported for the treatment of myotonia, were synthesized and evaluated in vitro as skeletal muscle sodium channel blockers possibly endowed with enhanced use-dependent behavior. Patch-clamp experiments on hNav1.4 expressed in HEK293 cells showed that N-[(naphthalen-1-yl)methyl]-4-[(2,6-dimethyl)phenoxy]butan-2-amine, the aryloxyalkyl bioisostere of To042, exerted a higher use-dependent block than To042 thus being able to preferentially block the channels in over-excited membranes while preserving healthy tissue function. It also showed the lowest active transport across BBB according to the results of P-glycoprotein (P-gp) interacting activity evaluation and the highest cytoprotective effect on HeLa cells. Quantum mechanical calculations and dockings gave insights on the most probable conformation of the aryloxyalkyl bioisostere of To042 in solution and the target residues involved in the binding, respectively. Both approaches indicated the conformations that might be adopted in both the unbound and bound state of the ligand. Overall, N-[(naphthalen-1-yl)methyl]-4-[(2,6-dimethyl)phenoxy]butan-2-amine exhibits an interesting toxico-pharmacological profile and deserves further investigation.

Beta-lactam-induced severe neutropaenia: a descriptive study

The objectives of this study were to describe the characteristics and natural history of beta-lactam-induced severe neutropaenia and to evaluate the risk of recurrences after another beta-lactam readministration. Reports of pure agranulocytosis associated with a beta-lactam exposure within the 10 days preceding the neutropaenia were extracted from the French Pharmacovigilance Database over the year 2010. Cases with another evident cause or more likely attributable to another drug were excluded. Data were analyzed for demographics, clinical and biological features, prognosis factors, granulocyte colony stimulating factors administration and outcome. Sixty-two cases were included (median age: 65 years). The median duration of treatment before neutropaenia was 16 days. In 47% of cases, the diagnosis was made on a systematic blood cell count. The median neutrophil count at nadir was 0.125 × 10⁹ /L, and bone marrow examination evidenced features of neutrophilic maturation arrest or aplasia in 21 patients, hyperplasia of granulopoietic cells in three and normal findings in five. Three patients developed severe sepsis. All but one recovered a normal blood cell count within 2-56 days after beta-lactam discontinuation. The last patient died from recurrent severe septic shock. No significant effect of granulocyte colony stimulating factor on the mean duration of haematological recovery was found. Among the 21 patients who later received another beta-lactam, two experienced recurrence of the neutropaenia after receiving a beta-lactam from another subfamily. Beta-lactam-induced agranulocytosis was usually observed after prolonged treatment, and severe complications are uncommon. In most patients, a subsequent treatment with another beta-lactam was well tolerated.

Nonchemotherapy drug-induced agranulocytosis in children detected by a prospective pharmacovigilance program

OBJECTIVES

A prospective evaluation of nonchemotherapy drug-induced agranulocytosis (DIA) cases, which are infrequent in the pediatric population. We characterize agranulocytosis cases and assess lab test differences between drug- and nondrug-induced agranulocytosis.

METHODS

Through our Prospective Pharmacovigilance Program from Laboratory Signals at Hospital we detected pediatric agranulocytosis cases from July 2007 to December 2010. This program estimates the incidence, drug causality, clinical features, outcomes of DIA pediatric cases, and assesses laboratory differences with respect to non-DIA.

RESULTS

We detected 662 agranulocytosis in 308 pediatric patients, of which 14 were caused by nonchemotherapy drugs. The incidence rate of DIA for 10,000 pediatric patients was 3.92 (Poisson 95% confidence interval 1.09-8.77); 78.6% of DIA cases occurred in patients younger than 3 years. The final outcome was recovery without sequela in all cases. The pharmacologic group most frequently implicated was antimicrobial drugs (11 drugs), 7 of which were beta-lactams. The drugs most frequently suspected were cefotaxime and vancomycin (3 cases each). We found 3 drugs (cloperastine, codeine, and enoxaparin) not previously described to induce DIA. Automatic linear modeling (n = 56, R² = 45.2%) showed a significant inverse association with platelets (R² = 17.5%), hemoglobin, and alanine transaminase, and a direct association with red cell distribution (R² = 16.2%). A generalized linear model (Type III, n = 1188; DIA, n = 86; likelihood ratio chi-squared = 156.16) retained eosinophils (p <.001), platelets (p <.001), total serum proteins (p <.001), and hemoglobin (p =.039).

CONCLUSIONS

We found a higher incidence of DIA in children than previously described. Our findings also suggest an immune-mediated destruction or myeloid toxicity, possibly facilitated by an increase in drug exposure.

Gold nanoparticles: A critical review of therapeutic applications and toxicological aspects

Gold (Au) compounds have been utilized as effective therapeutic agents for the treatment of some inflammatory diseases such as rheumatoid arthritis. However, Au compound use has become limited due to associated high incidence of side effects. Recent development of nanomaterials for therapeutic use with Au-containing drugs is improving the beneficial actions and reducing toxic properties of these agents. Lower toxicity in conjunction with anti-inflammatory and antiangiogenic effects was reported to occur with gold nanoparticles (AuNP) treatment. However, despite this therapeutic potential, safety of AuNP remains to be determined, since the balance between therapeutic properties and development of adverse effects is not well established. Several variables that drive this benefit-risk balance, including physicochemical characteristics of nanoparticles such as size, shape, surface area, and chemistry, are poorly described in the scientific literature. Moreover, therapeutic and toxicological data were obtained employing nonstandardized or poorly described protocols with different experimental settings (animal species/cell type, route and time of exposure). In contrast, effective and safe application of AuNP may be established only after elucidation of various physicochemical properties of each specific AuNP, and determination of respective kinetics and interaction of compound with target tissue. This critical review conveys the state of the art, the therapeutic use, and adverse effects mediated by AuNP, with primary emphasis on anti-inflammatory and antiangiogenic potential, highlighting the limitations/gaps in the scientific literature concerning important points: (i) selection of experimental designs (in vitro and in vivo models) and (ii) consideration of different physicochemical properties of AuNP that are often disregarded in many scientific publications. In addition, prospects and future needs for research in this area are provided.

Non-antiepileptic drugs for trigeminal neuralgia

BACKGROUND

Trigeminal neuralgia was defined by the International Association for the Study of Pain as a sudden, usually unilateral, severe, brief, stabbing recurrent pain in the distribution of one or more branches of the fifth cranial nerve. Standard treatment is with anti-epileptic drugs. Non-antiepileptic drugs have been used in the management of trigeminal neuralgia since the 1970s. This is an update of a review first published in 2006 and previously updated in 2011.

OBJECTIVES

To systematically review the efficacy and tolerability of non-antiepileptic drugs for trigeminal neuralgia.

SEARCH METHODS

On 20 May 2013, for this updated review, we searched the Cochrane Neuromuscular Disease Group Specialized Register, CENTRAL (2013, Issue 4), MEDLINE (January 1966 to May 2013), EMBASE (January 1980 to May 2013), LILACS (January 1982 to May 2013) and the Chinese Biomedical Retrieval System (1978 to May 2013). We searched clinical trials registries for ongoing trials.

SELECTION CRITERIA

We included double-blind, randomised controlled trials in which the active drug was used either alone or in combination with other non-antiepileptic drugs for at least two weeks.

DATA COLLECTION AND ANALYSIS

Two authors decided which trials fitted the inclusion criteria and independently graded risk of bias. We assessed the quality of the evidence according to the GRADE criteria for this update.

MAIN RESULTS

In this 2013 update, we updated the searches, but identified only two new ongoing studies. The review includes four trials involving 139 participants. The primary outcome measure in each was pain relief. Three trials compared one of the oral non-antiepileptic drugs tizanidine, tocainide or pimozide with carbamazepine. The quality of evidence for all outcomes for which data were available was low. In a trial of tizanidine involving 12 participants (one dropped out due to unrelated disease), one of five participants treated with tizanidine and four of six treated with carbamazepine improved (risk ratio (RR) 0.30, 95% confidence interval (CI) 0.05 to 1.89). Few side effects were noted with tizanidine. For pimozide, there was evidence of greater efficacy than carbamazepine at six weeks. Up to 83% of participants reported adverse effects but these did not lead to withdrawal; the report did not provide comparable data for carbamazepine. Limited data meant that we could not assess the effects of tocainide; however, data from non-randomised studies (not included in this review) indicate that serious haematological adverse events can occur. A trial involving 47 participants compared 0.5% proparacaine hydrochloride eyedrops with placebo but did not show any significant benefits, again according to low-quality evidence. The report did not mention adverse events. The proparacaine trial was at low risk of bias; the other trials were at unclear risk of bias overall.

AUTHORS' CONCLUSIONS

There is low-quality evidence that the effect of tizanidine is not significantly different than that of carbamazepine in treating trigeminal neuralgia. Pimozide is more effective than carbamazepine, although the evidence is of low quality and the data did not allow comparison of adverse event rates. There is also low-quality evidence that 0.5% proparacaine hydrochloride eye drops have no benefit over placebo. Limitations in the data for tocainide prevent any conclusions being drawn. There is insufficient evidence from randomised controlled trials to show significant benefit from non-antiepileptic drugs in trigeminal neuralgia. More research is needed.

Incidence, etiology and bone marrow characteristics of non-chemotherapy-induced agranulocytosis

OBJECTIVE

Agranulocytosis is a rare but fatal condition. The majority of cases are associated with drugs. However, in-patient incidences and the relationship between clinical outcomes and bone marrow characteristics have not been established.

METHODS

We conducted a retrospective study in a university hospital. A total of 38 in-patients diagnosed with agranulocytosis were analyzed.

RESULTS

The average incidence of agranulocytosis in Songklanagarind Hospital between 1993 and 2007 was 0·98 cases per 10 000 admissions per year. Antimicrobial agents were the most common etiology (63% of patients) and antithyroid agents were the second most common (13·6%). Two patterns of bone marrow were noted: type I was characterized by a left-shifted granulopoiesis and type II was recognized as having hypocellular bone marrow with markedly reduced granulocyte precursors. A significantly higher mortality was associated with type II.

CONCLUSION

Antimicrobial agents are the most common cause and the rare granulocyte precursors in bone marrow are associated with higher mortality rates.

Non-antiepileptic drugs for trigeminal neuralgia

BACKGROUND

Non-antiepileptic drugs have been used in the management of trigeminal neuralgia since the 1970s.

OBJECTIVES

The objective was to systematically review the efficacy and tolerability of non-antiepileptic drugs for trigeminal neuralgia.

SEARCH STRATEGY

For this updated review we searched the Cochrane Neuromuscular Disease Group Specialized Register (30 April 2010). We also searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2010, Issue 2), MEDLINE (January 1966 to April 2010), EMBASE (January 1980 to April 2010), LILACS (January 1982 to April 2010) and the Chinese Biomedical Retrieval System (1978 to April 2010). We handsearched 10 Chinese journals.

SELECTION CRITERIA

We searched for double-blind randomized or quasi-randomized controlled trials in which the active drug was used for at least two weeks.

DATA COLLECTION AND ANALYSIS

Two authors decided which trials fitted the inclusion criteria and independently graded risk of bias.

MAIN RESULTS

Four trials involving 139 participants were included. The primary outcome measure in each was pain relief. Three trials with an unclear risk of bias compared one of the non-antiepileptic drugs tizanidine, tocainide or pimozide with carbamazepine. In a trial of tizanidine involving 12 participants (one dropped out due to unrelated disease) one of five treated with tizanidine and four of six treated with carbamazepine improved, risk ratio 0.30 (95% CI 0.05 to 1.89). Few side effects were noted with tizanidine. In a study involving 12 participants there was an improvement in mean pain scores with tocainide similar to that with carbamazepine, but significant side effects limited its use. In the pimozide study more participants improved on pimozide (48/48) than with carbamazepine (27/48) (risk ratio 1.76, 95% CI 1.37 to 2.26). Up to 83% of participants reported adverse effects but these did not lead to withdrawal from the study. A trial with low risk of bias involving 47 participants compared 0.5% proparacaine hydrochloride eyedrops with placebo but did not show any significant benefits or side effects.

AUTHORS' CONCLUSIONS

Of the four studies identified, one had low and three an unclear risk of bias. There is insufficient evidence from randomized controlled trials to show significant benefit from non-antiepileptic drugs in trigeminal neuralgia. More research is needed.

Mexiletine is an effective antimyotonia treatment in myotonic dystrophy type 1

OBJECTIVE

To determine if mexiletine is safe and effective in reducing myotonia in myotonic dystrophy type 1 (DM1).

BACKGROUND

Myotonia is an early, prominent symptom in DM1 and contributes to decreased dexterity, gait instability, difficulty with speech/swallowing, and muscle pain. A few preliminary trials have suggested that the antiarrhythmic drug mexiletine is useful, symptomatic treatment for nondystrophic myotonic disorders and DM1.

METHODS

We performed 2 randomized, double-blind, placebo-controlled crossover trials, each involving 20 ambulatory DM1 participants with grip or percussion myotonia on examination. The initial trial compared 150 mg of mexiletine 3 times daily to placebo, and the second trial compared 200 mg of mexiletine 3 times daily to placebo. Treatment periods were 7 weeks in duration separated by a 4- to 8-week washout period. The primary measure of myotonia was time for isometric grip force to relax from 90% to 5% of peak force after a 3-second maximum grip contraction. EKG measurements and adverse events were monitored in both trials.

RESULTS

There was a significant reduction in grip relaxation time with both 150 and 200 mg dosages of mexiletine. Treatment with mexiletine at either dosage was not associated with any serious adverse events, or with prolongation of the PR or QTc intervals or of QRS duration. Mild adverse events were observed with both placebo and mexiletine treatment.

CONCLUSIONS

Mexiletine at dosages of 150 and 200 mg 3 times daily is effective, safe, and well-tolerated over 7 weeks as an antimyotonia treatment in DM1.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that mexiletine at dosages of 150 and 200 mg 3 times daily over 7 weeks is well-tolerated and effective in reducing handgrip relaxation time in DM1.

Access to linked administrative healthcare utilization data for pharmacoepidemiology and pharmacoeconomics research in Canada: anti-viral drugs as an example

PURPOSE

Administrative healthcare utilization data from Canadian provinces have been used for pharmacoepidemiology and pharmacoeconomics research, but limited transparency exists about opportunities for data access, who can access them, and processes to obtain data. An attempt was made to obtain data from all 10 provinces to evaluate access and its complexity.

METHODS

An initial enquiry about the process and requirements to obtain data on individual, anonymized patients dispensed any of four anti-viral drugs in the ambulatory setting, linked with data from hospital and physician service claims, was sent to each province. Where a response was encouraging, a technical description of the data of interest was submitted.

RESULTS

Data were unavailable from the provinces of New Brunswick, Newfoundland and Labrador, and Prince Edward Island, and inaccessible from British Columbia, Manitoba and Ontario due to policies that prohibit collaborative work with pharmaceutical industry researchers. In Nova Scotia, patient-level data were available but only on site. Data were accessible in Alberta, Quebec and Saskatchewan, although variation exists in the currency of the data, time to obtain data, approval requirements and insurance coverage eligibility.

CONCLUSIONS

As Canada moves towards a life-cycle management approach to drug regulation, more post-marketing studies will be required, potentially using administrative data. Linked patient-level drug and healthcare data are presently accessible to pharmaceutical industry researchers in four provinces, although only logistically realistic in three and limited to seniors and low-income individuals in two. Collaborative endeavours to improve access to provincial data and to create other data resources should be encouraged.

Incidence and risk factors of aplastic anemia in Latin American countries: the LATIN case-control study

Background Associations between aplastic anemia and numerous drugs, pesticides and chemicals have been reported. However, at least 50% of the etiology of aplastic anemia remains unexplained.

DESIGN AND METHODS

This was a case-control, multicenter, multinational study, designed to identify risk factors for agranulocytosis and aplastic anemia. The cases were patients with diagnosis of aplastic anemia confirmed through biopsy or bone marrow aspiration, selected through an active search of clinical laboratories, hematology clinics and medical records. The controls did not have either aplastic anemia or chronic diseases. A total of 224 patients with aplastic anemia were included in the study, each case was paired with four controls, according to sex, age group, and hospital where the case was first seen. Information was collected on demographic data, medical history, laboratory tests, medications, and other potential risk factors prior to diagnosis.

RESULTS

The incidence of aplastic anemia was 1.6 cases per million per year. Higher rates of benzene exposure (>/=30 exposures per year) were associated with a greater risk of aplastic anemia (odds ratio, OR: 4.2; 95% confidence interval, CI: 1.82-9.82). Individuals exposed to chloramphenicol in the previous year had an adjusted OR for aplastic anemia of 8.7 (CI: 0.87-87.93) and those exposed to azithromycin had an adjusted OR of 11.02 (CI 1.14-108.02). Conclusions The incidence of aplastic anemia in Latin America countries is low. Although the research study centers had a high coverage of health services, the underreporting of cases of aplastic anemia in selected regions can be discussed. Frequent exposure to benzene-based products increases the risk for aplastic anemia. Few associations with specific drugs were found, and it is likely that some of these were due to chance alone.

[Idiosyncratic drug-induced agranulocytosis]

Idiosyncratic drug-induced agranulocytosis is a potential adverse event of most drugs, rare but life-threatening. Its annual incidence does not exceed 10 cases per million population in Europe and has remained stable over the past two decades. Its pathogenesis is poorly understood. The principal drugs associated with it are antithyroid drugs, antibiotics including trimethoprim, sulfamethoxazole, and beta-lactamines, ticlopidine, sulfasalazine and dipyrone. Clinical presentation is highly variable but a severe infection is observed in more than one third of cases. Poor prognostic factors include a neutrophil count under 100/mm(3), age > 65 years, septicemia or shock, and severe comorbidity. Improvement in the management of infectious complications and the use of hematopoietic growth factors in severe cases helps explain that mortality rate has fallen to less than 5%.

Impact of valproates on haemostasis and blood cell count in children

INTRODUCTION Epilepsy is a highly prevalent disease affecting 0.5-1.5% of the world's population. One of the most frequently used antiepileptics are valproates. These medicines show a negative impact on haemostasis and peripheral blood count. OBJECTIVE The objective of the study was to examine the negative impact of valproates on haemostasis and peripheral blood count in children and to analyse whether these disturbances were dependent on the dosage of valproates and drug level in blood. METHOD A two-year research was conducted. The research included: 35 children using valproates, 12 children using the therapy of both valproates and carbamazepine and 30 healthy children. Complete peripheral blood count, screening tests of haemostasis (bleeding time, prothrombin time, prothrombin ratio, activated partial thromboplastin time, fibrinogen) and capacity of thrombocyte aggregation research were done in all the children. RESULTS We found significantly more common frequency of leukopenia and neutropenia in children using valproates in comparison with the healthy children group. We also found the more common frequency of eosinophilia in comparison with healthy children. The children with the valproate therapy have lower approximate values of the number of platelets, fibrinogen and platelet aggregation in comparison with healthy children, but they have a higher approximate value of bleeding time and prothrombin time. These disturbances are in correlation with the dosage and the level of the medicine in blood. CONCLUSION Valproates have a negative effect on certain blood count parameters and haemostasis in children. Drug dosage and blood drug level are correlated with their negative impact on haemostasis parameters.

Update: new uses for lithium and anticonvulsants

Anticonvulsants are being used clinically as monotherapy and adjuncts in mental illnesses other than affective disorders. This review focuses on the literature for anticonvulsants and lithium in substance use disorders, anxiety disorders, and schizophrenia. Given the abuse potential and other difficulties with prescribing benzodiazepines for alcohol and benzodiazepine withdrawal, anticonvulsants have been considered as an alternative. Promising therapeutic effects have been demonstrated in many of the anxiety disorders, with the greatest number of trials and positive results in posttraumatic stress disorder. Although anticonvulsant and lithium augmentation for schizophrenia is common in practice and has been studied in double-blind, randomized, controlled trials, the sum of the evidence has been inconclusive.

Non-chemotherapy drug-induced agranulocytosis

Acute agranulocytosis is a rare, potentially life-threatening condition, which is attributable to drugs in > 70% of cases. Agranulocytosis is characterised by a peripheral neutrophil count < 0.5 x 10(9)/l. It often manifests with a severe sore throat, but isolated fever, pneumonia or septicaemia are not uncommon. Agranulocytosis may be caused by many drugs. High-risk drugs include antithyroid drugs, clozapine, ticlopidine, sulfasalazine, dipyrone, trimethoprim/sulfamethoxazole, carbamazepine and probably rituximab. Suspect drugs should be stopped immediately. In febrile patients, blood cultures and, where indicated, site-specific cultures should be obtained and treatment with empirical broad spectrum antibiotics started. Haematopoietic growth factors should be considered in patients with poor prognostic factors (e.g., a neutrophil count < 0.1 x 10(9)/l), severe clinical infection or severe underlying disease or comorbidity. Case fatality has decreased to ~ 5% in recent years, probably owing to improved intensive care treatment and increased alertness of physicians to this severe adverse reaction.

Detection and incidence of drug-induced agranulocytosis in hospital: a prospective analysis from laboratory signals

AIMS

Our objectives were to assess the detection and incidence of drug-induced agranulocytosis in two university hospitals using hematology laboratory data.

METHODS

A prospective study was undertaken at Toulouse University Hospital (France) and Navarra University Hospital (Spain) for 1 year (from 1 May 2004 to 30 April 2005). Using a computerized process and hematology laboratory data, all neutrophil counts with a value less than 500/mm(3) were registered, allowing identification of inpatients suffering from agranulocytosis during the period of the study. Medical records of all selected patients were then consulted. Cytostatic drugs were excluded from this study.

RESULTS

During the period of the study, 225,659 neutrophil counts were performed in both hospitals, of which 2,835 (1.26%) had a neutrophil count less than 500/mm(3), corresponding to 739 patients. Seventeen patients were excluded because of lack of data, and 20 cases of infants younger than 3 months were excluded. Among the remaining patients (n = 702), 23 cases of drug-induced agranulocytosis (excluding cytostatic drugs) were suspected. All cases were classified as "serious" since they led to death in 2 cases, hospitalization or prolongation of hospitalization in 19 cases and threatening of vital prognosis in 2 cases. Withdrawal of suspected drugs was done in all cases with regression of neutropenia in 21 cases. According to hospitalization data, the annual incidence of drug-induced agranulocytosis was 1.62 (1.0-2.6) per 10,000 inpatients in Toulouse University hospital (based on 534 cases) and 3.24 (0.9-8.3) per 10,000 inpatients in Navarra University Hospital (based on 168 cases). The involved drugs were mainly antibacterial (30.4%), immunosuppressive (17.4%), antithyroid (13.0%), antiplatelet (8.7%) and nonsteroidal anti-inflammatory (8.7%) ones. Only seven cases from Toulouse University Hospital were spontaneously reported by physicians during the same period. Thus, the underreporting coefficient (U) was 2.71 (63.2%) in France.

CONCLUSION

Our survey allowed us to identify the suspected drug-induced agranulocytosis through a prospective study in a large sample of inpatients using only laboratory data analysis. We also note an important underreporting rate of this serious adverse drug reaction (ADR) to the official French pharmacovigilance system. Laboratory data analysis could be used for identifying serious ADRs.

Drug-Induced Thrombocytopenia

BACKGROUND

Drug-induced immune thrombocytopenia, excluding heparin-induced thrombocytopenia, is a rare adverse drug reaction for which the evidence about frequency, relative risk and risk factors mainly originates from case reports and case studies. This study aims to quantify the risk for thrombocytopenia following exposure to drugs that are most often reported to cause thrombocytopenia in the general population.

METHODS

A retrospective, case-control study was conducted within the PHARMO record linkage system. Cases were defined as patients hospitalised for thrombocytopenia in the period 1 January 1990 to 31 December 2002. For each case, up to four controls were matched based on age, sex and geographical area. Exposure on the index date to anticonvulsants, beta-lactam antibacterials, cinchona alkaloids, disease modifying antirheumatic drugs (DMARDs), diuretics, NSAIDs, sulfonamide antibacterials and tuberculostatics was assessed and categorised into mutually exclusive groups of current, recent, past and non-use. The risk was quantified with multivariate conditional logistic regression analysis.

RESULTS

The study population comprised 705 cases and 2658 controls. Current use of beta-lactam antibacterials was associated with an increased risk for thrombocytopenia (adjusted odds ratio 7.4, 95% CI 1.8, 29.6). Increased risk estimates, although not significant, were found for current exposure to DMARDs and the sulfonamide antibacterial cotrimoxazole (trimethoprim/sulfamethoxazole). No increased risk was found for anticonvulsants, cinchona alkaloids, diuretics, NSAIDs or tuberculostatics.

CONCLUSION

More evidence for an increased risk for thrombocytopenia in current use of beta-lactam antibacterials in the general population was provided. The expected increase in risk could not be confirmed for the other drugs investigated, which is possibly a result of the limited statistical power. Future studies including more patients and with laboratory data should confirm our findings before drawing definite conclusions.

Most severe neutropenia in individuals with no chronic condition did not result in a specific diagnosis

BACKGROUND AND OBJECTIVES

This study estimated the incidence of unexplained severe neutropenia (neutrophil count 500 x 10(6)/L) and hospitalized morbidity in the year after a finding of severe neutropenia in persons 2 years of age or older based on clinical laboratory data.

METHODS

Computer-stored data from the Kaiser Permanente Laboratory Management System/Results Management System were used to identify findings of severe neutropenia in members of Kaiser Permanente Southern California 2 years of age or older during the period January 1, 1997, through December 31, 1999. Computer record linkage and medical record review were used to exclude individuals with chronic disease or treatments with bone marrow toxic drugs known to cause neutropenia.

RESULTS

The incidence of findings of severe neutropenia was 47 per million persons per year (95% CI=42-53). Only 11% of individuals with a finding of severe neutropenia were hospitalized with neutropenia diagnosis. The hospitalization rate for infection occurring within 1 year of severe neutropenia was 3.2% (95% CI=1.5-6.2%).

CONCLUSION

Most laboratory findings of severe neutropenia in individuals with no chronic condition do not result in a specific diagnosis. In a population-based sample of findings of severe neutropenia identified by laboratory testing, hospitalization for infection was rare.

Safety of Calcium Dobesilate in Chronic Venous Disease, Diabetic Retinopathy and Haemorrhoids

The aim of the present review is to consider the adverse effects and the safety profile of calcium dobesilate. Calcium dobesilate (Doxium) is a veno-tonic drug, which is widely prescribed in more than 60 countries from Europe, Latin America, Asia and the Middle East for three main indications: chronic venous disease, diabetic retinopathy and the symptoms of haemorrhoidal attack. Data sources used for this review comprise the international literature (1970-2003), a postmarketing surveillance (PMS) report for calcium dobesilate from OM Pharma (Geneva, Switzerland) covering the period 1974-1998, and periodic safety update reports (PSUR) covering the period 1995-2003 from the French Regulatory authorities pharmacovigilance database and OM Pharma. Data from the PMS report for 1974-1998 indicated that adverse events with calcium dobesilate did not occur very frequently and had the following distribution in terms of frequency: fever (26%), gastrointestinal disorders (12.5%), skin reactions (8.2%), arthralgia (4.3%), and agranulocytosis (4.3%). No deaths were attributed to calcium dobesilate in the PMS report. Using data on product use in the Swiss Compendium we estimated the prevalence of agranulocytosis to be 0.32 cases/million treated patients, i.e. ten times less than the calculated prevalence of agranulocytosis in the general population. Most adverse events are type B, i.e. rare and unrelated to the pharmacological properties of calcium dobesilate. This review concludes that the risk of an adverse effect with calcium dobesilate 500-1500 mg/day is low and constant over time. The recently raised problem of agranulocytosis (a total of 13 known cases drawn from all data sources) appears to be related to methodological bias. Such a review reinforces the need for a strong international pharmacovigilance organisation using similar methods to detect and analyse the adverse effects of drugs.

Neutropenia and agranulocytosis in England and Wales: incidence and risk factors

The objectives of this study were to estimate the incidence of idiosyncratic neutropenia and agranulocytosis in England and Wales and to evaluate their risk factors and outcomes. The study was conducted using data from the General Practice Research Database. All cases of idiosyncratic neutropenia or agranulocytosis were identified and the incidence was estimated. This was followed by a nested case-control study, estimating odds ratios with drug exposure from conditional logistic regression. From 1987 to 1999, 3,224 patients with idiosyncratic neutropenia (50 with agranulocytosis) were identified. The incidences of neutropenia and agranulocytosis were estimated to be 120 and 7 cases per million people per year, respectively. The adjusted odds ratios for neutropenia were 34.7 (95% confidence interval 12.0-99.7) for current users of thyroid inhibitors, 9.5 (4.4-20.8) for users of disease-modifying antirheumatic drugs, and 7.6 (4.9-11.9) for users of aminosalicylates. Other drugs with statistically significantly increased risks of neutropenia included antibacterial drugs, non-opioid analgesics, NSAIDs, antidepressants, ulcer-healing drugs, and anti-epileptics. The increase in risk of neutropenia predominantly occurred during the first months of treatment. For most drugs investigated in this study, there was no relationship to daily dose. The excess 1-year mortality was low among neutropenia and agranulocytosis cases and mostly explained by the underlying disease state. In conclusion, the highest risks of neutropenia were generally found in patients starting treatment. The excess 1-year mortality was low among neutropenia and agranulocytosis cases and can be mostly explained by the underlying disease state.

Adverse effects of observational studies when examining adverse outcomes of drugs: case-control studies with low prevalence of exposure

OBJECTIVES

The case-control study is commonly used to examine adverse drug events, in which prevalence of exposure in the source population is frequently very low. The objective of the current study was to examine the bias inherent in the odds ratio assessing the association between exposure and an adverse outcome when prevalence of exposure in the source population is extremely low.

DESIGN

Monte Carlo simulations examined the effect of sample size, exposure prevalence, and magnitude of the underlying odds ratio on the bias of the estimated risk ratio, and the power to detect a non-zero risk ratio.

RESULTS

Once the underlying odds ratio was at least four, the adverse effects of low prevalence of exposure was minimal. Studies with small sample sizes and low prevalence of exposure, coupled with small to moderate effect sizes, can result in biased estimates of association between exposure and disease status. With a sample size of 200 and an exposure prevalence of 0.5% in the control population, the bias in the estimated odds ratio can be as large as 115%. However, bias becomes negligible as sample size becomes large (n > or = 2000), even when prevalence of exposure is very low. Once the expected number of exposed controls is at least eight, the bias in the estimated odds ratio was no more than 5%.

CONCLUSIONS

Studies with small sample sizes and low prevalence of exposure, coupled with small to moderate effect sizes can result in biased estimates of association between exposure status and adverse drug effects. However, bias becomes negligible as sample size becomes large.

Risk of clinical blood dyscrasia in a cohort of antibiotic users

Blood dyscrasias, although rare, can be fatal. Many drugs, including antibiotics, are associated with these dyscrasias. We conducted a cohort study with a nested case-control analysis using data from the General Practice Research Database to estimate incidence rates of clinical blood dyscrasias in the general population and to examine their association with use of antibiotic drugs. The study population consisted of patients aged 5-69 years receiving at least one antibiotic prescription from January 1994-September 1998. The final cohort consisted of 822,048 persons who received 1,507,307 antibiotic prescriptions during the study period. The main outcome measure was a diagnosis of neutropenia, agranulocytosis, hemolytic anemia, thrombocytopenia, bicytopenia, pancytopenia, or aplastic anemia. We confirmed 122 patients who developed clinical blood dyscrasias. The incidence was 3.3/100,000 person-years in the general population. Patients older than 60 years (relative risk [RR] 2.8, 95% confidence interval [CI] 1.6-5.0) and those who took phenothiazines (RR 49.0, 95% CI 4.9-488.2) had an increased risk of blood dyscrasia. Users of antibiotics had an RR of 4.4 (95% CI 2.6-7.5), and patients taking more than one class of antibiotics had an RR of 29.1 (95% CI 9.1-92.8). Among individual antibiotic classes, the greatest risk was with cephalosporins (RR 13.8, 95% CI 3.6-52.6). Although uncommon, our study supports an association between blood dyscrasias and antibiotics.

Inherited muscle and brain channelopathies

In the past 5 years, advances in the complementary fields of neurogenetics and cellular electrophysiology have resulted in an explosion of knowledge about a group of disorders now known as the neurological channelopathies. These advances have resulted in more accurate DNA-based diagnosis and have increased our understanding of cellular pathophysiology. This is leading to more tailored therapies for patients with these disorders.

Concordance on the recording of cancer in the Saskatchewan Cancer Agency Registry, hospital charts and death registrations

Accurate and complete registries are an important source of knowledge about cancer. The concordance of the recording of neoplasms in the Saskatchewan cancer registry with that in hospital charts and death registrations was evaluated for 368 patients. The agreement between registry and hospital charts or death registrations was excellent (kappa: 0.93; 95% confidence interval: 0.89, 0.97), with 91.3% of those with cancer having the same neoplasm recorded in their chart or death registration as in the registry. There was only one patient whose hospital chart indicated cancer who was not in the registry and one apparent major discrepancy relating to the cancer site, which was due to the recording of the primary site in the registry and a secondary in the hospital chart. Although based on a relatively small number of patients, these results suggest a high degree of consistency between cancer registry, hospital charts and death registrations in Saskatchewan.