Understanding adverse drug reactions in older adults through drug-drug interactions

AIMS

The aims of this study are to evaluate prevalence and characteristics of adverse drug reactions (ADRs) and to evaluate the potential contribution of specific medications, therapeutic categories and drug-drug interactions (DDIs) in older adults.

METHODS

All ADR reporting forms of persons aged 65+ years collected by the pharmacovigilance of one of the main hospitals in Italy during 2013 were evaluated. DDIs were analysed by a computerized prescription system (INTERCheck) and based on the interactions' database managed by the Istituto di Ricerche Farmacologiche Mario Negri. DDIs were classified according to their clinical relevance as contraindicated, major, and moderate.

RESULTS

Amongst all the ADR reporting forms (n=1014) collected during 2013, 343 affected older adults. The most frequent ADRs were: haemorrhages (n=122, 35.5%), allergic reactions (n=56, 16.3%), and elevated International Normalized Ratio (INR>6, n=54, 15.7%). The specific medications that contributed to ADRs were warfarin (42.5%), acenocumarol (9%), and allopurinol (8.5%); while the therapeutic categories were haematological agents (67%) and proton pump inhibitors (13%). A total of 912 DDIs were found; one third of them were contraindicated or major and 31.5% of them potentially contributed to ADRs; of these, the most frequent were: warfarin and heparin (contraindicated, n=5); warfarin and a statin (major, n=38); warfarin and a proton pump inhibitor (moderate, n=40). At least one DDI contributed to 66 haemorrhages out of 122 (54%) and to 41 elevated INR out of 54 (76%).

CONCLUSION

DDIs significantly contribute to the onset of ADRs in older adults and intervention programmes, e.g., the employment of a computerized system, may reduce the burden of iatrogenic illnesses in the elderly.

Predictors of Clinical Progression among HIV-1–Positive Patients starting HAART with CD4+ T-cell Counts ≥200 cells/mm3

Background

Baseline and follow-up predictors of new AIDS-defining events (ADE) or death among patients who started HAART with CD4+ T-cell counts ≥200 cells/mm3 have rarely been assessed simultaneously.

Methods

A prospective observational cohort study (1996–2002) is reported. HIV-infected patients initiating HAART with a CD4+ T-cell count ≥200 cells/mm3 were studied. Baseline and time-varying factors were tested for the prediction of new ADE/death using Cox regression models.

Results

A total of 896 subjects were studied over a median of 5.1 years. The incidence of a new ADE was 1.6 (95% confidence interval 1.3–2.1) per 100 person-years. Among baseline factors, higher CD4+ T-cell counts before HAART were associated with lower risk of ADE/death, but not after adjustment for time-varying factors. On a multivariable analysis including both baseline and time-varying covariates, longer delay from HIV diagnosis to HAART was an independent predictor of ADE/death (per year, hazard ratio [HR] 1.06; P=0.025) and was independent of CD4+ T-cell count before treatment. Longer time spent with HIV RNA <400 copies/ml (per month, HR 0.96; P=0.003) and higher latest CD4+ T-cell count (per log2 cells/mm3, HR 0.65; P<0.001) were found to be protective.

Conclusions

Patients with higher CD4+ T-cell counts before HAART initiation had a better prognosis. However, except for the delay in starting HAART, viro-immunological evolution outweighed the effect of baseline factors. Moreover, suppressing HIV replication for as long as possible could improve the clinical outcome. Prospective randomized clinical trials to assess the optimal timing of HAART initiation are both feasible and urgently needed.

Assessment of inertial and gravitational inputs to the vestibular system

A new device for the assessment of instantaneous angular and linear accelerations of the head is presented, which is based on four linear tri-axial accelerometers suitably attached to the head by an helmet. A procedure for reproducible helmet placement and calibration is given. A method is also illustrated to work out the different linear accelerations sensed by the vestibular organs in the left and right labyrinths and the components of the angular acceleration sensed by their semicircular canals. The computation is based on few individual parameters describing the helmet position with respect to external landmarks and on the average internal position and orientation of the vestibula. The purpose is to study the components of internal inertial forces, which represent the primary inputs to the vestibular system devoted to equilibrium and oculomotor control. The system is designed to be of easy application during rehabilitation exercises and in clinical environment during diagnostic and therapeutic manoeuvres. The prototype is tested with simple free movements such as "yes", "no", and gait.