Page 16 - Drug Class Review

Final Report Update 1 Drug Effectiveness Review Project

RESULTS

We identified 1,167 citations from searches and reviews of reference lists; we identified no unpublished

trials from dossiers submitted by pharmaceutical companies. In total we included 46 studies: 31 RCTs, 8
meta-analyses or systematic reviews, and 7 studies of other design. Furthermore, we retrieved 59 articles
for background information. We could not retrieve six articles after multiple attempts. 21-26 For some

studies, the investigators published more than a single article; therefore, numbers of referenced articles
may not always sum to the number of studies (Figure 1, QUORUM Tree).

Reasons for exclusions were based on eligibility criteria or methodological criteria. We excluded nine
studies that met the eligibility criteria but were later rated as poor quality for internal validity from the

analysis (Appendix D). The main reasons for a poor quality rating were high study attrition rates among
RCTs and lack of systematic literature search for meta-analyses. Lack of a systematic literature search
leads to a selected spectrum of trials and biased results.

Of 46 included studies, 74 percent were supported financially by pharmaceutical companies; 17 percent
were funded by governmental agencies or independent funds. We could not determine the funding source

for 9 percent of included studies.

Studies reviewed for this report employed several different instruments for assessing symptoms, health
status, or quality of life. Table 3 summarizes symptom assessment scales and health status or quality-of-
life instruments encountered in this literature and used in this report.

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