Age- and gender-related use of low-dose drug therapy: the need to manufacture low-dose therapy and evaluate the minimum effective dose

OBJECTIVES

Low-dose drug therapy is promoted as a way to maximize benefit and minimize adverse drug effects when prescribing for older adults. This population-based study evaluates the age and sex-related use of two common therapies: thiazide diuretics, where evidence supports the use of low-dose therapy, and beta-blockers, where trials have not evaluated the minimum effective dose.

DESIGN

Using linked administrative databases we identified all of the 120,613 persons dispensed a thiazide diuretic therapy and 12,908 myocardial infarction survivors dispensed beta-blocker therapy in Canada's largest province. We used logistic regression models to study the association of age and sex with dispensing of low-dose thiazide diuretic and beta-blocker therapy at doses lower than evaluated in trials.

RESULTS

Of 120,613 older people dispensed a thiazide diuretic, 32,372 (26.8%) were dispensed a low dose. Patients 85 years of age or older, relative to the youngest group, were 30% more likely to be dispensed low-dose therapy (OR=1.31; 95% CI, 1.27 to 1.36; P < .001). Women were 8% more likely than men to be dispensed a low-dose thiazide diuretic (OR=1.08; 95% CI, 1.05 to 1.11; P < .001). Of 10,991 myocardial infarction survivors dispensed atenolol, metoprolol, propranolol, or timolol, 9458 (86.1%) were dispensed a lower-than-evaluated dose. Patients 85 years of age or older, relative to those in the youngest group, were more than twice as likely to be dispensed a lower-than-evaluated beta-blocker therapy dose (OR=2.28; 95% CI, 1.74 to 3.04; P < .001). No difference was noted in the use of beta-blocker therapy dose by sex (OR=1.0; 95% CI, .89 to 1.15; P = .95).

CONCLUSIONS

Low-dose thiazide diuretic therapy prescribed widely to older people, particularly those of advanced age and women. The vast majority of myocardial infarction survivors were dispensed beta-blocker therapy at lower-than-evaluated doses. These findings highlight the need to manufacture low-dose thiazide diuretic therapy and to evaluate the minimum effective dose of beta-blocker therapy.

Enhanced differential diagnosis of anticonvulsant hypersensitivity reactions by an integrated Bayesian and biochemical approach

OBJECTIVE

The differential diagnosis of hypersensitivity reactions associated with anticonvulsants requires accuracy because of the many implications for patient management. We tested an integrated Bayesian and biochemical diagnostic approach.

METHODS

The patients were analyzed clinically by two tests. One test, the Bayesian Adverse Reaction Diagnostic Instrument (BARDI), calculates the posterior probability of a drug being the cause based on epidemiologic and case data. The other, the lymphocyte toxicity assay, is an in vitro rechallenge that determines the percentage of cell death attributable to a drug's toxic metabolites. The setting for the study was an adverse drug reaction clinic at Sunnybrook Health Science Centre and the Hospital for Sick Children, Toronto, Ontario, Canada. Fifty-one patients who had hypersensitivity reactions after receiving aromatic anticonvulsants were tested. Four of these patients had more than one reaction reported, with different anticonvulsants generating 56 distinct events.

RESULTS

Compared to the lymphocyte toxicity assay, BARDI had 94% sensitivity, 93% accuracy, and 50% specificity. When lymphocyte toxicity assay data were incorporated into BARDI, agreement rose from 93% to 100%. BARDI also identified which drug was a more likely cause for 11 patients receiving multiple anticonvulsants.

CONCLUSION

These findings show that BARDI and the lymphocyte toxicity assay have high concordance and, when used in an integrated approach, these tests can improve the diagnostic accuracy and enhance the management of patients with hypersensitivity reactions.

Serious dermatologic reactions in children

Although serious reactions comprise only a small percentage of total adverse drug reactions, they are important in terms of morbidity and potential mortality. An update on serious dermatologic reactions in children is presented including serum sickness-like reactions due to cefaclor, hypersensitivity syndrome reactions (HSRs), and drug-induced pseudoporphyria. More detailed information on minocycline-induced reactions including drug-induced lupus and HSRs and lamotrigine-induced toxic epidermal necrolysis and Stevens-Johnson syndrome will be discussed.

Improving the diagnosis of hypersensitivity reactions associated with sulfonamides

The differential diagnosis of idiosyncratic adverse drug reactions (ADRs) is difficult because symptoms are seldom pathognomonic. The authors compared the performance of two new diagnostic aids in the differential diagnosis of 27 cases of skin reactions associated with sulfonamide therapy. One test, the Bayesian Adverse Reaction Diagnostic Instrument (BARDI), calculates the posterior probability (PsP) of a drug being the etiology of an idiosyncratic ADR. The other, the lymphocyte toxicity assay (LTA), is a biochemical test that determines the percent of cell death because of toxic metabolites of a drug. Cases were assessed independently and blindly by BARDI and then the LTA. Skin reactions consisted of 19 exanthematous eruptions, 2 vasculitis, 1 erythema multiforme, and 5 urticarial rashes. BARDI indicated that the drug was very likely associated with 20 adverse events (PsP = 0.59 to 0.99); and unlikely to have caused 7 (PsP = 0.02 to 0.38). The LTA showed that 19 patients (70%) were test positive, and 8 were test negative. Comparing BARDI to LTA showed that BARDI had 79% sensitivity and 67% accuracy, but only 38% specificity. However, when the results of the LTA were incorporated into the calculation of the PsP based on this comparison, BARDI indicated that the drug was very likely associated with 18 reactions (PsP = 0.61 to 0.99) and unlikely to have caused 9 reactions (PsP = 0.003 to 0.47). The agreement increased from 67% to 96%. These findings indicate that the accuracy of diagnosis of idiosyncratic ADRs improved when the results of BARDI and LTA were combined. These findings also crossvalidate the results obtained by using BARDI.

Quantifying the costs of serious adverse drug reactions to antiepileptic drugs

PURPOSE

We assessed from an institutional perspective the direct costs of severe adverse cutaneous or hypersensitivity reactions due to antiepileptic drug (AED) therapy that led to hospitalization or prolonged hospital stay.

METHODS

Patients admitted for or developing severe AED-induced cutaneous or hypersensitivity reactions while in hospital from January 1990 through June 1996 were identified by ICD-9 codes E936, E937, E693, E695.1, E995.1, and E995.2. Identified cases were analyzed retrospectively by chart review and were included in the analysis if a causal relationship was determined to be possible, probable, or definite. Clinical outcomes were abstracted and related direct costs of the adverse drug reactions (ADRs) calculated.

RESULTS

A total of 384 cases were identified by ICD-9 codes, of which 13 cases (mean age +/- SD 52.9+/-21.0 years) were included for further analysis. Eight patients (62%) were admitted because of an ADR (median length of stay 9.5 days; range 4-43), five (38%) experienced an ADR during hospitalization (median duration of ADR episodes 8.5 days; range: 7-21 days). The median direct medical costs of the ADRs were Canadian (CDN) $3,128 (range 1,149-21,293) per patient.

CONCLUSIONS

The management of serious cutaneous and hypersensitivity ADRs due to AEDs is associated with considerable direct medical costs. These figures should be considered along with drug acquisition costs and treatment of clinical successes and failures in the overall assessment of the economic impact of pharmacotherapy. Prospective collection of direct costs associated with ADRs in clinical trials would be of value.

Neuroblastoma after prenatal exposure to phenytoin: cause and effect?

We evaluated the causality of the association between intrauterine exposure to phenytoin and postnatal neuroblastoma using an in vitro lymphocyte toxicity assay for phenytoin-induced reactions in an unusual sibship. In addition, we investigated intrauterine phenytoin exposure in a case series of infants and children with neuroblastoma diagnosed over 17 years at our center. The response of lymphocytes from our index case with neuroblastoma exposed in utero to phenytoin was within the normal range, whereas the mother and a sibling with fetal hydantoin syndrome (FHS) exhibited an intermediate toxicity. None of the 188 cases of childhood neuroblastoma diagnosed between 1969 and 1988 had been exposed in utero to phenytoin, indicating that, statistically, the drug cannot be associated with neuroblastoma in more than two cases with this malignancy in our cohort, or in 1.5% of all cases of neuroblastoma. Although our data do not suggest an association between phenytoin in pregnancy and postnatal neuroblastoma, it is still possible that there is an increased risk for neuroblastoma in children with FHS.

Pancreatic insufficiency due to antituberculous therapy

OBJECTIVE

To describe a case of chronic pancreatic insufficiency related to antituberculous therapy.

CASE SUMMARY

A 57-year-old man developed rash, fever, and hepatitis (aspartate aminotransferase 369 IU/L, alanine aminotransferase 506 IU/L), 6 weeks after starting isoniazid, rifampin, ethambutol, and pyrazinamide. He also developed severe metabolic acidosis secondary to diabetic ketoacidosis and lactic acidosis (serum bicarbonate 7 mEq/L, glucose 1778 mg/dL, and lactate 4.0 mEq/L). Acute pancreatitis was diagnosed on the basis of a mildly elevated amylase concentration (392 U/L) and radiologic evidence of pancreatic inflammation. He developed pancreatic insufficiency with steatorrhea and an abnormal secretin test. He continues to require pancreatic enzyme replacement and insulin therapy. Rechallenge was not performed.

DISCUSSION

Hypersensitivity syndromes have been reported for various drug therapies, including antituberculous agents. Hypersensitivity syndrome reactions are characterized by fever, rash, and internal organ involvement. Rifampin has been reported to cause acute pancreatitis in up to 2.7% of patients. Drug-induced chronic pancreatitis, however, is reported to be extremely rare. This is the first reported case of chronic pancreatic insufficiency occurring in the setting of a hypersensitivity syndrome reaction to antituberculous drugs.

CONCLUSIONS

Chronic pancreatic insufficiency should be considered as a possible long-term sequelae of a hypersensitivity syndrome reaction to antituberculous therapy.

Clinical and economic factors in the treatment of onychomycosis

Onychomycosis is a fungal infection of fingernails and toenails, most cases of which are caused by dermatophytes. The disease accounts for 15% of all nail disease, and affects approximately 2 to 3% of people of all ages and both sexes. Topical treatment with tioconazole, amorolfine or ciclopirox has limited effectiveness. Oral griseofulvin 500 to 1000mg daily has been the mainstay of treatment, but prolonged therapy is required and success rates are low. Therapy with itraconazole 200mg daily for 3 to 6 months is more effective (70 to 85% success), although so-called 'pulse' therapy has shown similar success with potentially fewer adverse effects. Terbinafine 250mg daily produces clinical and mycological cure in approximately 80% of patients treated for 6 and 12 weeks for fingernail and toenail infections, respectively. The overall costs of treating onychomycosis are substantial, and it has been estimated that direct costs for Medicare patients with the disease were $US43 million in 1 year. In addition, the disease has a negative impact on quality of life, in the domains of mental functioning, health concern, social functioning, and physical appearance. Few pharmacoeconomic analyses have been published, but all have indicated an advantage of oral terbinafine over griseofulvin and other oral agents. To date, no economic studies have been performed on topical agents, pulse therapy or combination treatments.

Cytokine network in nonresponding chronic hepatitis C patients with genotype 1: role of triple therapy with interferon alpha, ribavirin, and ursodeoxycholate

OBJECTIVE

(i) to characterize the profile of tumor necrosis factor alpha (TNF alpha), interleukin-6 (IL-6), IL 10, Fas-ligand and transforming growth factor beta (TGF beta), chronic hepatitis C (HCV) patients with genotype 1; (ii) to determine the influence of triple therapy (TT) with interferon alpha (IFN alpha) + ribavirin + ursodeoxycholic acid on these cytokines and (iii) to establish the relationship between the pro-inflammatory cytokines and the outcome of treatment.

DESIGN AND METHODS

22 patients infected with HCV-genotype 1 a/b and non responsive to IFN-alpha monotherapy were enrolled in the TT. The controls were 49 HCV naïve patients with genotype 1 a/b. Cytokine levels were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

The baseline TNF alpha values (pg/mL) in the sustained responders (SRs) (63+/-3) were significantly lower than non-responders (NRs) (140+/-16) (p < 0.001). Baseline Fas (ng/mL) levels were also lower in SRs (4.3+/-0.2) than NRs (5.4+/-0.4) (p < 0.05).

CONCLUSIONS

Fas and TNF alpha may be used as serological markers of inflammation and effectiveness of therapy.

The effectiveness of antidepressants in elderly depressed outpatients: a prospective case series study

BACKGROUND

This study examined the effectiveness of antidepressants in a group of elderly depressed outpatients by assessing depression prevalence and recording adverse events over time.

METHOD

A prospective practice-based observational study (1991-1994) included consecutive outpatients at least 65 years of age with a DSM-III-R diagnosis of major affective disorder and who were prescribed antidepressant medications. Depressive symptoms were examined over time (stage 1 = 0 to 2 months; stage 2 = 2 to 6 months; stage 3 = 6 months to 2 years) with the Montgomery-Asberg Depression Rating Scale (MADRS). The cutoff scores of MADRS <18 and MADRS > or =18 were used in survival statistics. Adverse events were recorded systematically.

RESULTS

A total of 213 patients were seen over 2677 visits (mean +/- SD age = 75.5+/-6.1 years). MADRS scores for 85.8% of patients declined to below 18 within the first 2 months of antidepressant treatment. MADRS scores were above 18 for 37.3% of patients after 6 months and for 37.1% after 2 years. The mean time to decline in MADRS scores to below 18 in stage 1 was 36.1 days, and there was a significant difference between the antidepressant classes (log rank = 8.3, df = 3, p = .04), with tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs)/reversible inhibitors of monoamine oxidase A (RIMAs) having shorter times to response. The mean time to reach scores above cutoff during stage 2 was 144.3 days (log rank = 5.7, df = 3, p = .13) and during stage 3, 538.6 days (log rank = 9.8, df = 3, p = .02). Patients receiving TCAs and MAOIs/RIMAs had longer durations of MADRS scores below cutoff during stage 3 than those taking atypical antidepressants and selective serotonin reuptake inhibitors. All antidepressant classes reported similar adverse event profiles.

CONCLUSION

This study systematically examined antidepressant effectiveness in a prospective design. TCAs and MAOIs/RIMAs were shown to be superior in effectiveness during 2 of the 3 treatment stages.