Although silver NPs provide many benefits, prolonged exposure to soluble silver-containing compounds may produce an irreversible pigmentation in the skin (argyria) and the eyes (argyrosis) in addition to other toxic effects [10].
Even in the absence of controlled randomized trial, the absence of evidence regarding the benefit of prolonged treatment lead to progressively decrease treatment duration in our population, without increasing failure rate over years (data not shown).
More recently, the CREDO trial suggested an incremental benefit of prolonged (one year) use of clopidogrel in addition to aspirin in 2116 patients undergoing elective PCI. 13 Long term clopidogrel treatment was associated with a 26.9% RRR in the combined risk of death, myocardial infarction, or stroke (95% CI 3.9%too 44.4%; p = 0.02; absolute reduction, 3%).
She cited a 2008 study in the journal Pediatrics, in which the authors concluded there was no "evidence of risks or benefits of prolonged and exclusive breast-feeding for child and maternal behavior".
The benefits of prolonged and early initiated breastfeeding are well documented.
The long-term benefits of prolonged post-exposure prophylaxis against recurrent parasitemia have yet to be determined.
Finally, our study does not compare the cost-effectiveness ratios associated with these treatments since it is obvious that these approved drugs deliver clinical benefits including prolonged survival.
In sockeye salmon, nest destruction is shown to cause strong selection for increased longevity (time from start of breeding until death) among early, but not late breeding females due to the benefits of prolonged nest guarding (Hendry et al. 2004).
In these cases, the investigators' clinical judgment and expectation that patients would benefit from further letrozole treatment was given priority over strict adherence to the protocol schedule, with the result that three of the four patients benefited from prolonged letrozole therapy.
The same pattern was observed for 17HSD type 2 alone, that is, ER-positive patients with low expression benefited from prolonged treatment, whereas those showing higher type 2 levels appeared to have similar recurrence-free survival with 2 and 5 years of treatment (5 vs 2 years, RR=0.60 (95% CI, 0.35 1.04) and RR=1.01 (0.28–3.6), respectively).
