Systematic Reviews of Animal Experiments Demonstrate Poor Human Clinical and Toxicological Utility

The assumption that animal models are reasonably predictive of human outcomes provides the basis for their widespread use in toxicity testing and in biomedical research aimed at developing cures for human diseases. To investigate the validity of this assumption, the comprehensive Scopus biomedical bibliographic databases were searched for published systematic reviews of the human clinical or toxicological utility of animal experiments. In 20 reviews in which clinical utility was examined, the authors concluded that animal models were either significantly useful in contributing to the development of clinical interventions, or were substantially consistent with clinical outcomes, in only two cases, one of which was contentious. These included reviews of the clinical utility of experiments expected by ethics committees to lead to medical advances, of highly-cited experiments published in major journals, and of chimpanzee experiments — those involving the species considered most likely to be predictive of human outcomes. Seven additional reviews failed to clearly demonstrate utility in predicting human toxicological outcomes, such as carcinogenicity and teratogenicity. Consequently, animal data may not generally be assumed to be substantially useful for these purposes. Possible causes include interspecies differences, the distortion of outcomes arising from experimental environments and protocols, and the poor methodological quality of many animal experiments, which was evident in at least 11 reviews. No reviews existed in which the majority of animal experiments were of good methodological quality. Whilst the effects of some of these problems might be minimised with concerted effort (given their widespread prevalence), the limitations resulting from interspecies differences are likely to be technically and theoretically impossible to overcome. Non-animal models are generally required to pass formal scientific validation prior to their regulatory acceptance. In contrast, animal models are simply assumed to be predictive of human outcomes. These results demonstrate the invalidity of such assumptions. The consistent application of formal validation studies to all test models is clearly warranted, regardless of their animal, non-animal, historical, contemporary or possible future status. Likely benefits would include, the greater selection of models truly predictive of human outcomes, increased safety of people exposed to chemicals that have passed toxicity tests, increased efficiency during the development of human pharmaceuticals and other therapeutic interventions, and decreased wastage of animal, personnel and financial resources. The poor human clinical and toxicological utility of most animal models for which data exists, in conjunction with their generally substantial animal welfare and economic costs, justify a ban on animal models lacking scientific data clearly establishing their human predictivity or utility

Intravenous Thrombolysis in Patients With Ischemic Stroke Aged ≥90 Years: A Cohort Study From the TRISP Collaboration

Background: The probability to receive intravenous thrombolysis (IVT) for treatment of acute ischemic stroke declines with increasing age and is consequently the lowest in very elderly patients. Safety concerns likely influence individual IVT treatment decisions. Using data from a large IVT registry, we aimed to provide more evidence on safety of IVT in the very elderly. Methods: In this prospective multicenter study from the TRISP (Thrombolysis in Ischemic Stroke Patients) registry, we compared patients ≥90 years with those <90 years using symptomatic intracranial hemorrhage (ECASS [European Cooperative Acute Stroke Study]-II criteria), death, and poor functional outcome in survivors (modified Rankin Scale score 3-5 for patients with prestroke modified Rankin Scale score ≤2 and modified Rankin Scale score 4-5 for patients prestroke modified Rankin Scale ≥3) at 3 months as outcomes. We calculated adjusted odds ratio with 95% CI using logistic regression models. Results: Of 16 974 eligible patients, 976 (5.7%) were ≥90 years. Patients ≥90 years had higher median National Institutes of Health Stroke Scale on admission (12 versus 8) and were more often dependent prior to the index stroke (prestroke modified Rankin Scale score of ≥3; 45.2% versus 7.4%). Occurrence of symptomatic intracranial hemorrhage (5.7% versus 4.4%, odds ratioadjusted 1.14 [0.83-1.57]) did not differ significantly between both groups. However, the probability of death (odds ratioadjusted 3.77 [3.14-4.53]) and poor functional outcome (odds ratioadjusted 2.63 [2.13-3.25]) was higher in patients aged ≥90 years. Results for the sample of centenarians (n=21) were similar. Conclusions: The probability of symptomatic intracranial hemorrhage after IVT in very elderly patients with stroke did not exceed that of their younger counterparts. The higher probability of death and poor functional outcome during follow-up in the very elderly seems not to be related to IVT treatment. Very high age itself should not be a reason to withhold IVT. © 2022 American Heart Association, Inc