You will be provided with the titles and abstracts of a collection of medical RCT reports studying a clinical question -- for instance, the efficacy of an intervention on some medical outcome. Please write a few sentences synthesizing the findings of these reports, which could serve as a conclusion section for a systematic review article. Your response should not include any other text. The RCT reports are below.



Title 1:
NGX-4010, a high-concentration capsaicin patch, for the treatment of postherpetic neuralgia: a randomised, double-blind study.
Abstract 1:
The limitations of current treatments for postherpetic neuralgia (PHN) have led to the investigation of localised, non-systemic alternatives. NGX-4010, a high-concentration (8%) capsaicin dermal patch, was developed to treat patients with neuropathic pain. We report the results of a randomised, double blind, 12-week study of the efficacy and safety of one application of NGX-4010 in patients with PHN.
                In this multicentre, double-blind, parallel-group trial, 402 patients were randomly assigned to one 60-min application of NGX-4010 (640 microg/cm(2) [8% capsaicin]) or a low-concentration capsaicin control patch (3.2 microg/cm(2) [0.04% capsaicin]). Patients were aged 18-90 years, had had postherpetic neuralgia for at least 6 months, and had an average baseline numeric pain rating scale (NPRS) score of 3 to 9. The primary efficacy endpoint was percentage change in NPRS score from baseline to weeks two to eight. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT00115310.
                Patients who were randomly assigned to NGX-4010 (n=206) had a significantly greater reduction in pain during weeks two to eight than did patients who had the control patch (n=196). The mean changes in NPRS score were -29.6%vs -19.9% (difference -9.7%, 95% CI -15.47 to -3.95; p=0.001). 87 (42%) patients who received NGX-4010 and 63 (32%) controls had a 30% or greater reduction in mean NPRS score (odds ratio [OR] 1.56, 95% CI 1.03 to 2.37; p=0.03). The patients who had NGX-4010 had significant improvements in pain during weeks two to 12 (mean change in NPRS score -29.9%vs -20.4%, difference -9.5, -15.39 to -3.61; p=0.002). Transient blood pressure changes associated with changes in pain level were recorded on the day of treatment, and short-lasting erythema and pain at the site of application were common, self-limited, and generally mild to moderate in the NGX-4010 group and less frequent and severe in the controls.
                One 60-min application of NGX-4010 provided rapid and sustained pain relief in patients with postherpetic neuralgia. No adverse events were associated with treatment except for local reactions at the site of application and those related to treatment-associated pain.


Title 2:
Controlled trial of high-concentration capsaicin patch for treatment of painful HIV neuropathy.
Abstract 2:
HIV-associated distal sensory polyneuropathy (HIV-DSP) is a painful condition with limited effective treatment. Capsaicin desensitizes cutaneous nociceptors resulting in reduced pain. We report a placebo-controlled study of a high-concentration capsaicin dermal patch (NGX-4010) for the treatment of painful HIV-DSP.
                This double-blind multicenter study randomized 307 patients with painful HIV-DSP to receive NGX-4010 or control, a low-concentration capsaicin patch. After application of a topical anesthetic, NGX-4010 or control was applied once for 30, 60, or 90 minutes to painful areas on the feet. The primary efficacy endpoint was percent change in Numeric Pain Rating Scale (NPRS) from baseline in mean "average pain for past 24 hours" scores from weeks 2 to 12.
                A single NGX-4010 application resulted in a mean pain reduction of 22.8% during weeks 2 to 12 as compared to a 10.7% reduction for controls (p = 0.0026). Following a transient treatment-related pain increase, pain was reduced; significant improvement was apparent by week 2 and continued throughout the controlled 12-week observation period. Mean pain reductions in the NGX-4010 30-, 60- and 90-minute groups were 27.7%, 15.9%, and 24.7% (p = 0.0007, 0.287, and 0.0046 vs control). One third of NGX-4010-treated patients reported >or=30% pain decrease from baseline as compared to 18% of controls (p = 0.0092). Self-limited, mild-to-moderate local skin reactions were commonly observed.
                A single NGX-4010 application was safe and provided at least 12 weeks of pain reduction in patients with HIV-associated distal sensory polyneuropathy. These results suggest that NGX-4010 could provide a promising new treatment for painful HIV neuropathy.


Title 3:
A multicenter, randomized, double-blind, controlled study of NGX-4010, a high-concentration capsaicin patch, for the treatment of postherpetic neuralgia.
Abstract 3:
To confirm the efficacy, tolerability, and safety of NGX-4010, an 8% capsaicin dermal patch (capsaicin 640 µg/cm(2) ), in patients with postherpetic neuralgia (PHN). PHN is a chronic pain disorder that can be difficult to treat and for which current treatment options are often limited by poor tolerability.
                A total of 418 patients were randomized to receive a single 60-minute application of NGX-4010 or a 0.04% capsaicin control patch (3.2 µg/cm(2) ) in a multicenter, double-blind, confirmatory, phase 3 study.
                Patients were 18-90 years old with a diagnosis of PHN, pain for at least 6 months, and an average baseline Numeric Pain Rating Scale (NPRS) score of 3-9.
                The primary efficacy end point was the percentage change in NPRS score from baseline to weeks 2-8.
                NGX-4010 recipients had a significantly greater mean reduction from baseline in pain during weeks 2-8 compared with the control group (32.0% vs 24.4%; P=0.011). A ≥ 30% reduction in mean NPRS scores was achieved in 46% of NGX-4010 recipients compared with 34% of controls (P=0.02). Pain was significantly lower in NGX-4010 recipients than controls by week 2, and greater pain reduction was maintained throughout the remaining 12-week study period. Most treatment-emergent adverse events were application site specific (notably erythema and pain), transient, and generally mild to moderate in severity.
                In patients with PHN, a single 60-minute application of NGX-4010 produced significant reduction in pain that was maintained over a 12-week period.
                Wiley Periodicals, Inc.


Title 4:
A multicenter, randomized, double-blind, controlled dose finding study of NGX-4010, a high-concentration capsaicin patch, for the treatment of postherpetic neuralgia.
Abstract 4:
Postherpetic neuralgia (PHN) is a painful complication of acute herpes zoster. This multicenter, double-blind, controlled study randomized 299 PHN patients to receive either NGX-4010, a high-concentration capsaicin (8%) patch, or a low-concentration capsaicin (0.04%) control patch for 30, 60, or 90 minutes. The mean percent reductions in NPRS score from baseline to weeks 2 through 8 were significantly greater in the total NGX-4010 group (26.5%, P = .0286) and the 90-minute NGX-4010 group (27.8%, P = .0438) compared to the pooled control group (17.3%). After review of the data suggested a difference between genders in reporting of pain scores and a higher proportion of males (61%) in the 60-minute NGX-4010 group, post hoc gender-stratified analyses were performed and showed that the 60-minute NGX-4010 group also had a significantly larger mean percent reduction in average pain scores (28.0%, P = .0331). Pain reduction in the 30-minute NGX-4010 group, although similar in magnitude to the other doses, was not significantly different from control in either of these analyses. Similar results were observed during weeks 2 through 12. Most treatment-emergent adverse events were application-site specific, transient and mostly mild to moderate in severity.
                This article reports the safety and efficacy of NGX-4010 applied for 3 different durations (30, 60, or 90 minutes) in patients with PHN. The results identified the 60-minute duration as the dose to be evaluated in subsequent studies and identified a gender effect on reported changes in pain.
                Copyright © 2010. Published by Elsevier Inc.


Title 5:
Effect of duration of postherpetic neuralgia on efficacy analyses in a multicenter, randomized, controlled study of NGX-4010, an 8% capsaicin patch evaluated for the treatment of postherpetic neuralgia.
Abstract 5:
Postherpetic neuralgia (PHN) is a painful and difficult to treat complication of acute herpes zoster. Current treatment options provide only partial relief and are often limited by poor tolerability. We evaluated the safety and efficacy of a single 60-minute application of NGX-4010, an 8% capsaicin patch, in patients with PHN.
                This multicenter, double-blind, controlled study randomized 155 patients 2:1 to receive either NGX-4010 or a 0.04% capsaicin control patch. Patients were at least 18 years old with PHN for at least 3 months, and an average Numeric Pain Rating Scale (NPRS) score of 3 to 9. The primary efficacy endpoint was the percentage change in NPRS score from baseline to weeks 2-8.
                The mean percent reduction in "average pain for the past 24 hours" NPRS scores from baseline to weeks 2-8 was greater in the NGX-4010 group (36.5%) compared with control (29.9%) although the difference was not significant (p = 0.296). PGIC analysis demonstrated that more NGX-4010 recipients considered themselves improved (much, or very much) compared with control at weeks 8 and 12, but the differences did not reach statistical significance. Post hoc analyses of patients with PHN for at least 6 months showed significantly greater reductions in "average pain for the past 24 hours" NPRS scores from baseline to weeks 2-8 in NGX-4010 patients compared to controls (37.6% versus 23.4%; p = 0.0291). PGIC analysis in this subgroup demonstrated that significantly more NGX-4010 recipients considered themselves much or very much improved compared with control at week 12 (40% versus 20%; p = 0.0403;).
                Although treatment appeared to be safe and well tolerated, a single 60-minute application of NGX-4010 failed to show efficacy in this study which included patients with PHN for less than 6 months. Large reductions in pain observed among control patients with pain for less than 6 months may have been due to spontaneous resolution of PHN, may have confounded the results of the prespecified analyses, and should be taken into account when designing PHN studies.
                NCT00068081.


Title 6:
A randomized, double-blind, controlled study of NGX-4010, a capsaicin 8% dermal patch, for the treatment of painful HIV-associated distal sensory polyneuropathy.
Abstract 6:
Effective treatment of HIV-associated distal sensory polyneuropathy remains a significant unmet therapeutic need.
                In this randomized, double-blind, controlled study, patients with pain due to HIV-associated distal sensory polyneuropathy received a single 30-minute or 60-minute application of NGX-4010--a capsaicin 8% patch (n = 332)--or a low-dose capsaicin (0.04%) control patch (n = 162). The primary endpoint was the mean percent change from baseline in Numeric Pain Rating Scale score to weeks 2-12. Secondary endpoints included patient global impression of change at week 12.
                Pain reduction was not significantly different between the total NGX-4010 group (-29.5%) and the total control group (-24.5%; P = 0.097). Greater pain reduction in the 60-minute (-30.0%) versus the 30-minute control group (-19.1%) prevented intended pooling of the control groups to test individual NGX-4010 treatment groups. No significant pain reduction was observed for the 30-minute NGX-4010 group compared with 30-minute control (-26.2% vs.-19.1%, respectively, P = 0.103). Pain reductions in the 60-minute NGX-4010 and control groups were comparable (-32.8% vs. -30.0%, respectively; P = 0.488). Posthoc nonparametric testing demonstrated significant differences favoring the total (P = 0.044) and 30-minute NGX-4010 groups (P = 0.035). Significantly, more patients in the total and 30-minute NGX-4010 group felt improved on the patient global impression of change versus control (67% vs. 55%, P = 0.011 and 65% vs. 45%, P = 0.006, respectively). Mild to moderate transient application site pain and erythema were the most common adverse events.
                Although the primary endpoint analyses were not significant, trends toward pain improvement were observed after a single 30-minute NGX-4010 treatment.
High-concentration topical capsaicin used to treat postherpetic neuralgia and HIV-neuropathy generates more participants with high levels of pain relief than does control treatment using a much lower concentration of capsaicin. The additional proportion who benefit over control is not large, but for those who do obtain high levels of pain relief there are additional improvements in sleep, fatigue, depression and an improved quality of life. High-concentration topical capsaicin is therefore similar to other therapies for chronic pain. In this case, the high cost of single and repeated applications suggest that high-concentration topical capsaicin is likely to be used when other available therapies have failed, and that it should probably not be used repeatedly without substantial documented pain relief. Even when efficacy is established, there are unknown risks, especially on epidermal innervation, of repeated application of long periods.