Independent Studies Find DynaMed Fastest at Including New Evidence

DynaMed Weekly Update - Volume 6, Issue 38

Evidence-based clinical references must be regularly updated to provide the best current evidence available, but the approaches used to maintain currency differ among reference databases. A new study prospectively evaluated the rates at which new evidence is added to several of these databases. Researchers in Italy tested Clinical Evidence, DynaMed, EBM Guidelines, eMedicine and UpToDate (BMJ 2011 Sep 23;343:d5856). They identified 128 systematic reviews selected by leading evidence-based collections to represent the most important new evidence and monitored the databases starting two months after publication to see when these reviews would appear in clinical reference content.

At 2 months, DynaMed had evidence summaries of more than 60% of these reviews, increasing to 77% at 3 months and 87% at 9 months. Rates of inclusion for all the other databases were less than 50% of these reviews at 9 months: 4% for Clinical Evidence, 41% for EBM Guidelines, 12% for eMedicine and 29% for UpToDate (p

< 0.05 for each vs. DynaMed). The median time to inclusion of evidence was 7.7 weeks for DynaMed and 42 weeks for EBM Guidelines. Median times to inclusion were not reached (exceeded 1 year) for Clinical Evidence, eMedicine, and UpToDate. In a separate study, another set of clinical references (ACP PIER, BMJ Point of Care, Cline-eguide, DynaMed, Epocrates, Essential Evidence Plus, FirstConsult, and UpToDate) was assessed for the frequency of updates to treatment sections for the top 10 diagnoses (J Med Libr Assoc 2011 Jul;99(3):247). The mean time between updates was 19 days for DynaMed and 199-449 days for the other databases.


Noninvasive Ventilation Reduces Mortality and Need for Intubation in Elderly Patients with Acute Hypercapnic Respiratory Failure

Noninvasive ventilation reduces the need for intubation compared to standard medical care in adults with acute exacerbation of chronic obstructive pulmonary disease (COPD) (Lancet 2000 Jun 3;355(9219):1931, Chin Med J (Engl) 2005 Dec 20;118(24):2034). There is also evidence that noninvasive ventilation may reduce mortality in these patients (Crit Care Med 2002 Mar;30(3):555). Alternatives to intubation are especially important in older patients who may have “do not intubate” (DNI) orders. A new randomized trial evaluated the effects of noninvasive ventilation on mortality and need for intubation in elderly patients with hypercapnic respiratory failure (80% with COPD). Eighty-two patients (mean age 81 years) were randomized to noninvasive ventilation vs. standard medical therapy. Inclusion criteria included pH< 7.35, respiratory rate >20 breaths/minute, and severe dyspnea. Need for intubation was defined as the presence of 1 major factor or 2 minor factors after 1 hour postrandomization. Major factors included no improvement or worsening of pH, deteriorating neurological status, loss of consciousness, and hemodynamic instability with loss of alertness. Minor factors included continued dyspnea, respiratory rate > 35 breaths/minute, and weak cough reflex with accumulation of secretions.

Noninvasive ventilation significantly reduced the need for intubation (7.3% vs. 63.4%, p< 0.001, NNT 2), in-hospital mortality (2.4% vs. 14.6%, p = 0.04, NNT 9), and total mortality at 12 months (39% vs. 61%, p = 0.014, NNT 5) (level 1 [likely reliable] evidence). The mean improvement in dyspnea score at 1 hour was 1 point in the ventilation group vs. 0.4 points in the standard care group (on 0-10 scale, p = 0.05).

Additional analysis of these data suggests that noninvasive ventilation may reduce mortality compared to intubation in patients meeting intubation criteria. Only 6 patients who met the criteria (2 from the ventilation group and 4 from the standard care group) actually received intubation. Due to DNI orders, a total of 22 patients (21 from the standard care group) who met intubation criteria had noninvasive ventilation only as rescue therapy. In observational analysis based on treatment received, the highest mortality at 12 months was in the intubation group (83%). Mortality was 56% in patients who received only standard medical care and 43% in patients receiving ventilation (p< 0.05 comparing ventilation vs. intubation) (level 2 [mid-level] evidence) (Age Ageing 2011 Jul;40(4):444).

For more information, see the Noninvasive positive pressure ventilation (NPPV) in adults topic in DynaMed.

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