Clinical trials treatment control

Although chemonucleolysis has been used for more than 25 years as an alternative treatment for sciatica, there has always been controversy as to its use, and to date many physicians ore still reluctant to use it. Because or the controversial results, it seems desirable to take a closer look at this important feature. In the first clinical series of 75 patients published, 75% good results were reported, although 39% of patients had severe muscle spasms and an increase in back pain for a few days r92], This phenomenon was also reported by others. In recent clinical trials (properly controlled, double-blind prospective studies), an overall success rate of about 70 85% has been reported [93-95J. 

Finally, it is appropriate to reinforce the general message. Controlled clinical trials demand controlled comparisons. These consist of direct comparisons between treatments, for example, in the form of differences. 

Control. A term which can be used in a number of ways in clinical trials but which is always related to the idea of controlling for various sources of bias. In a controlled (parallel) clinical trial, the control group is a group of patients otherwise presumed similar to the patients given the experimental treatment, but who are given an alternative treatment (for example, a placebo) in order to provide a standard of comparison for the experimental treatment. 

Clinical Trials In controlled clinical trials in patients with asthma, the onset of improvement in pulmonary function, as measured by maximum midexpiratory flow rate (MMEF), was within 30 minutes after a dose of albuterol tablets, with peak improvement occurring between 2 and 3 hours. In controlled clinical trials in which measurements were conducted for 6 hours, clinically significant improvement (defined as maintaining a 15% or more increase in forced expiratory volume in 1 second [FEVj] and a 20% or more increase in MMEF over baseline values) was observed in 60% of patients at 4 hours and in 40% at 6 hours. In other single-dose, controlled clinical trials, clinically significant improvement was observed in at least 40% of the patients at 8 hours. No decrease in the effectiveness of albuterol tablets was reported in patients who received long-term treatment with the drug in uncontrolled studies for periods up to 6 months. 

Several clinical trials have been conducted with streptokinase adrninistered either intravenously or by direct infusion into a catheterized coronary artery. The results from 33 randomized trials conducted between 1959 and 1984 have been examined (75), and show a significant decrease in mortaUty rate (15.4%) in enzyme-treated patients vs matched controls (19.2%). These results correlate well with an ItaUan study encompassing 11,806 patients (76), in which the overall reduction in mortaUty was 19% in the streptokinase-treated group, ie, 1.5 million units adrninistered intravenously, compared with placebo-treated controls. The trial also shows that a delay in the initiation of treatment over six hours after the onset of symptoms nullifies any benefit from this type of thrombolytic therapy. Conversely, patients treated within one hour from the onset of symptoms had a remarkable decrease in mortaUty (47%). The benefits of streptokinase therapy, especially in the latter group of patients, was stiU evident in a one-year foUow-up (77). In addition to reducing mortahty rate, there was an improvement in left ventricular function and a reduction in the size of infarction. Thus early treatment with streptokinase is essential. 

So far, five different protease inhibitors have been approved by the FDA for the treatment of HIV infection [3, 4]. Clinical trials in which protease inhibitors were evaluated in monotherapy demonstrated the potency of this class of inhibitors (decrease in HIV RNA levels, increase in CD4 cell counts). Treatment regimens were subsequently broadened to include reverse transcriptase inhibitors in combination with protease inhibitors. The result of these clinical trials has led to a list of guidelines with recommendations for the optimal treatment options. Prolonged control of the infection with combination therapy (highly active antiretroviral therapy, HAART ) could be shown. 

It has been proposed that the development of the complications of diabetes mellitus may be linked to oxidative stress and therefore might be attenuated by antioxidants such as vitamin E. Furthermore, it is discussed that glucose-induced vascular dysfunction in diabetes can be reduced by vitamin E treatment due to the inactivation of PKC. Cardiovascular complications are among the leading causes of death in diabetics. In addition, a postulated protective effect of vitamin E (antioxidants) on fasting plasma glucose in type 2 diabetic patients is also mentioned but could not be confirmed in a recently published triple-blind, placebo-controlled clinical trial [3]. To our knowledge, up to now no clinical intervention trials have tested directly whether vitamin E can ameliorate the complication of diabetes. 

Kranzler HR, Wesson DR, Billot L Naltrexone depot for treatment of alcohol dependence a multicenter, randomized, placebo-controlled clinical trial. Alcohol Clin... 

Johnson A, Jasinski DR, Galloway GP, et al Ritanserin in the treatment of alcohol dependence a multi-center clinical trial. Psychopharmacol 128 206—215, 1996 Johnson BA, Roache JD, Javors MA, et al. Ondansetron for reduction of drinking among biologically predisposed alcoholic patients a randomized controlled trial. JAMA 284 963-971, 2000... 

Szeimies RM, Gerritsen MJ, Gupta G, Ortonne JP, Serresi S, Bichel J, Lee JH, Fox TL, Alomar A (2004) Imiquimod 5% cream for the treatment of actinic keratosis results from a phase III, randomized, double-blind, vehicle-controlled, clinical trial with histology. J Am Acad Dermatol 51 547-555... 

Figure 27.2 A display that summarizes the duration of treatment (black sqnares) and the timing of serious vascular events (circles) for the subset of patients who withdrew from treatment because of an adverse event. Each line represents a single patient s experience over time in days for the test (left panel) and the control drug (right panel). Patients are sorted by decreased duration of treatment. In this 1 1 randomized clinical trial there were 18 withdrawals due to a severe vascular adverse event with the test drug. This is in contrast with the control drug, with 11 withdrawals. Withdrawals with the test drug occurred sooner than with the control drug.

Randomized, controlled clinical trials reduce bias and variability by a process of selection, randomization and standardization of treatment, and often take place under artificial conditions isolated from those of routine clinical practice (Freemande et al, 1993 Simon et al, 1995b). Yet it is the uncontrolled interactions of a dmg technology with patients, health-care workers and the system of health care that ultimately lead to much of the variability in outcomes and expenditures in clinical practice. Thus the value of RCTs in evaluating cost-effectiveness in clinical practice maybe limited (Reeder, 1995 Simon et al, 1995b Hotopf et al, 1996). 

For any intervention intended to impact favorably upon human health, it is important to evaluate its safety and efficacy in order to demonstrate that it does not cause harm and it does provide the expected benefit. The gold standard method for evaluating any intervention, whether it be a botanical product, dietary supplement, drug, medical device or medical procedure, is the randomized, clinical trial (RCT). A clinical trial is a type of experiment conducted in human subjects where the effects of at least two interventions are compared. Often, the clinical trial takes the form of an active treatment compared to an inactive control or placebo. 

There are two main types of clinical trial design, parallel and cross-over. In a parallel study, subjects are assigned to one of two or more treatments, e.g. active and placebo, and proceed through the trial concurrently. In a cross-over design, subjects act as their own controls, undergoing two or more treatments in sequence (see Fig. 12.1). 

KLIPPEL K F, HiLTL D M, scHipp B (1997) A multicentric placebo controlled double-blind clinical trial of beta-sitosterol for the treatment of benign prostate hyperplacia. British J Urology, 80(3) 427-32. 

In randomized, controlled, clinical trials, calcium channel blockers were as effective as p-blockers at preventing ischemic symptoms. Calcium channel blockers are recommended as initial treatment in IHD when /3-blockers are contraindicated or not tolerated. In addition, CCBs may be used in combination with /3-blockers when initial treatment is unsuccessful. However, the combination of a (1-blocker with either verapamil or diltiazem should be used with extreme caution since all of these drugs decrease AV nodal conduction, increasing the risk for severe bradycardia or AV block when used together. If combination therapy is warranted, a long-acting dihydropyridine CCB is preferred. (3-Blockers will prevent reflex increases in sympathetic tone and heart rate with the use of calcium channel blockers with potent vasodilatory effects. 

---