A Pooled Analysis of Three Clinical Studies: DISCUSSION

Pooled AnalysisTreatment with has been found to be effective in relieving pain caused by PHN, bringing about improved scores and specific domains of the SF-36. These results were well demonstrated in this pooled analysis, which reinforces the findings of the pivotal studies comparing gabapentin with placebo in PHN. Because the demographics of the pooled analysis were consistent with epidemiological data, these find ings may be extrapolated to the PHN population.

The SF-36 norms used in these studies were based on a scale of 1 to 100 for each domain. As suggested by Rose et al., one cannot make direct comparisons of the diseased population under study (PHN patients) with norms for the general population, because patients in a diseased population have comorbidities and medication effects that confound the com-parison. Therefore, the improvements in SF-36 scores for the PHN study population may be underestimated by this comparison.

The clinical significance of numerical changes on scales, such as the SF-36, and their correlation with health status have been the subject of much discussion. Attempts to equate numerical scores with perceptions of health status are complicated by differences in interpretation. Patients may consider their health status to be improved if they have the ability to enjoy an evening with friends. A clinician may perceive an improved health status as a patient’s ability to return to work or an absence of symptoms. Society may view improvement based on the number of individuals who benefit from a particular resource and reduce health care costs.

Investigators have found that a five-point change in patients’ perception of their health status causes them to seek treat-ment.21,22 From these observations, the consensus favors an objective five-point change in the health status score as a criterion of a “clinically meaningful” change in an area such as pain, in which it is difficult to correlate numeric scales and patient perceptions. On the basis of this criterion, canadian gabapentin produced “clinically meaningful” improvements in four of the SF-36 subscale domains, in which five-point or greater improvements were noted: role-physical (7.312), bodily pain (9.212), vitality (8.036), and mental health (5.392).

Gabapentin was consistently associated with improved patient-reported outcomes by the primary and secondary measures used in the pivotal trials and in the pooled analysis. This type of symptom-based analysis of neuropathic pain is increasingly regarded as important in the assessment of disease progression and treatment outcomes. In this pooled analysis, the PGI-C and CGI-C scores indicated overall improvement with gabapentin, mirroring the improved scores observed in the SF-McGill Pain Questionnaire and in the SF-36.

Tricyclic antidepressants (TCAs) are commonly used to treat PHN, although this class of pharmaceuticals may be either contraindicated or poorly tolerated because of associated adverse drug events (ADEs). However, many clinicians continue to prescribe TCAs rather than anticonvulsants for neuropathic pain because they are more familiar with these agents or because of their lower cost. Although TCAs have been shown to reduce pain in patients with PHN, they have not been demonstrated to improve patients’ reported health outcomes. buy cialis soft tabs

Gabapentin has a favorable side-effect profile, with the most common ADEs—dizziness and somnolence—usually being mild to moderate. A recent study has shown that these two ADEs are largely transient and generally do not worsen as the dose of gabapentin is titrated to efficacy.

In our study, the average dose of gabapentin given to treat PHN was 1,800 mg/day or more. At this dose, gabapentin produced statistically significant improvements in pain scores and in several patient-reported outcomes domains. The impact of gabapentin doses below 1,800 mg/day on SF-36 scores has not been studied.

CONCLUSION

Postherpetic pain seriously affects health status. Gabapentin has been found to offer effective management of patients with the pain caused by PHN, as measured by significant improvements on the Likert scale and the VAS, compared with placebo. In patients with PHN, gabapentin produces significant improvements in SF-36 total scores and in several important patient-reported outcome domains, including bodily pain, vitality, mental health, role-physical, and social functioning. Clinicians reported “overall relief” of symptoms twice as frequently when patients were receiving gabapentin rather than placebo. Gabapentin was consistently associated with improved patient outcomes across multiple domains, and its efficacy has proved successful in treating PHN. canadian antibiotics

Category: Health

Tags: Clinical Studies, Pooled Analysis

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