Cochrane for Clinicians

Putting Evidence into Practice

Are Oral Betamimetics Effective Maintenance Therapies After Threatened Preterm Labor?

GLENN GRIFFIN, M.D., Ontario, Canada

The Cochrane Abstract is a summary of a review from the Cochrane Library. It is accompanied by an interpretation that will help clinicians put evidence into practice. Dr. Griffin presents a clinical scenario and question based on the Cochrane Abstract, followed by an evidence-based answer and a critique of the review. The practice recommendations in this activity are available at http://www.cochrane.org/reviews/ en/ab003927.html.

Clinical Scenario

A pregnant patient presents to the hospital at 31 weeks' gestation with preterm contractions. After the patient receives hydration and terbutaline (Brethine), the contractions stop.

Clinical Question

Should an oral betamimetic be used as maintenance therapy to prevent preterm delivery after treatment for threatened preterm labor?

Evidence-Based Answer

There is no evidence to support the use of oral betamimetics for maintenance therapy after treatment for threatened preterm labor, and there is a risk of adverse effects with these drugs.1

Practice Pointers

Despite the lack of evidence of their effectiveness and the potential for adverse effects, many physicians continue to use betamimetics. This Cochrane review included 11 randomized controlled trials (RCTs) with a total of 1,238 women. Eight of the RCTs compared an oral betamimetic with placebo or no treatment, one compared an oral betamimetic with the nonsteroidal anti-inflammatory drug indomethacin (Indocin), one compared two betamimetics, and three compared an oral betamimetic with magnesium (some trials had more than two arms). The precision of the results is somewhat low because serious outcomes were uncommon; however, the consistency of the results lends weight to their validity.

The American College of Obstetricians and Gynecologists (ACOG) guideline on the management of preterm labor states that there is good and consistent evidence that "neither maintenance treatment with tocolytics [such as betamimetics] nor repeated acute tocolysis improves perinatal outcomes, so neither should be undertaken as a general practice." Instead, ACOG recommends that tocolytic drugs be used once (probably given intravenously in the hospital) to prolong the pregnancy for two to seven days. This may allow the physician to administer steroids to improve fetal lung maturity and to consider transporting the mother to a tertiary care facility.2

Address correspondence to Glenn Griffin, M.D., at ghgriffin@hotmail.com Reprints are not available from the author.

Author disclosure. Nothing to disclose.

REFERENCES

1. Dodd JM, Crowther CA, Dare MR, Middleton P. Oral betamimetics for maintenance therapy after threatened preterm labour. Cochrane Database Syst Rev 2006;(1):CD003927.

2. American College of Obstetricians and Gynecologists. ACOG practice bulletin. Management of preterm labor. No. 43, May 2003. Obstet Gynecol 2003;101 (5 pt 1):1039-47.

Cochrane Briefs

Effectiveness of Dressings for Healing Venous Leg Ulcers

Clinical Question

Is one dressing superior to others when used for healing venous leg ulcers?

Evidence-Based Answer

No single dressing or type of dressing appears to be superior to others in the complete healing of ulcers or in healing rate.

Practice Pointers

Family physicians commonly encounter patients with venous leg ulcerations. A previous Cochrane review on the management of these ulcers noted that compression bandages or stockings improve ulcer healing.1 However, the best dressing to place directly on the ulcer before applying a compression dressing is unclear. The ideal dressing would keep the wound moist, allowing cells to proliferate and migrate while excess drainage is absorbed. Many types of dressings are available. This Cochrane review evaluated whether one dressing provides superior healing compared with others.

The analysis included 42 prospective randomized controlled trials with 3,001 total patients. The dressings (Table 1) included hydrocolloids, hydrogels, alginates, foam dressings, bead dressings, and dry gauze. Most trials were small, ranging from 13 to 200 participants. The length of trials ranged from four to 40 weeks, with an average of 14 weeks of follow-up. The small sample size and short duration may have limited the ability of the studies to detect clinically important differences.

table 1 Dressings Commonly Used for Healing Venous Leg Ulcers
Dressing	Description
Alginates	Fibrous dressing, derived from seaweed, that absorbs fluid; creates gel to keep wound moist; allows gas exchange; prevents contamination (e.g., Kaltostat, Sorbsan)
Bead dressings	Absorbs wound exudates, debris, and bacteria; a separate dressing is required to hold beads in place (e.g., Debrisan)
Foam dressings	Absorbs exudates into foam, keeping the wound moist (e.g., Lyofoam, Allevyn, Cavicare)
Hydrocolloids	Occlusive dressing that absorbs wound exudates and liquefies to keep the wound moist; impervious to gas, bacteria, and liquid (e.g., Coloplast, Duoderm)
Hydrogels	Flat sheets of starch polymer that absorb wound exudates or rehydrate the wound based on wound moisture levels (e.g., Geliperm, Intrasite Gel, Vigilon)
Semipermeable film dressings	Transparent film that keeps the wound moist; allows some gas exchange; impervious to bacteria (e.g., Bioclusive, Opsite, Tegaderm)
Wound dressing pads	Includes simple nonadherent dressings, knitted viscose dressings, and medicated or nonmedicated dressings (e.g., Adaptec, Silvadene, and Betadine impregnated gauze; sterile gauze; Tricotex)

Thirty-one trials (74 percent) used the total number of healed ulcers as the primary outcome; the remaining studies used rate of healing as the primary outcome. However, healing rates may not correspond with complete healing of the ulcer.

Trials comparing hydrocolloids with low-adherent dressings included the most participants (n = 792). These trials showed that hydrocolloids were not superior to simple, low-adherent dressings. Other dressing comparisons also demonstrated no superiority.

The authors note a number of limitations in many of the studies that may limit the strength of their conclusions: small sample size and limited study duration, unspecified randomization techniques, and researchers who were unblinded to the treatment group. Only five studies were deemed to be of high methodologic quality.

There is insufficient evidence to recommend one type of dressing over another. The need for large, high-quality trials on this topic is evident because a lack of evidence does not necessarily equal a lack of effectiveness.

PABLO LOPEZ, M.D.

ROBERT DACHS, M.D.

Source: Palfreyman SJ, et al. Dressings for healing venous leg ulcers. Cochrane Database Syst Rev 2006;(3):CD001103.

REFERENCE

1. Cullum N, Nelson EA, Fletcher AW, Sheldon TA. Compression for venous leg ulcers. Cochrane Database Syst Rev 2001;(2):CD000265.

Telephone Counseling Improves Smoking Cessation Rates

Clinical Question

Does telephone counseling help smokers quit?

Evidence-Based Answer

Telephone counseling can improve long-term smoking cessation rates. Multiple proactive calls are more effective than a single reactive call.

Practice Pointers

Telephone counseling services (called quitlines, helplines, or hotlines) may offer counseling for smoking cessation. Telephone counseling can be a single session in response to a smoker's call (i.e., reactive), multiple sessions initiated by a counselor (i.e., proactive), or a combination of these types. Telephone counseling services are readily available to smokers who are planning a quit attempt or to former smokers trying to avoid a relapse. These services reach an estimated 1 to 6 percent of adult smokers each year, and some target specific at-risk populations such as pregnant, adolescent, or low-income smokers.1

This Cochrane review identified 48 randomized or quasirandomized trials evaluating telephone counseling for smokers or for those who have recently quit smoking. All trials measured abstinence from smoking for at least six months. Comparison groups generally received brief advice from a physician during an office visit and/or printed self-help materials. Reactive interventions showed no significant effect (two trials; n = 1,804; pooled odds ratio [OR] = 1.12; 95% confidence interval [CI], 0.84 to 1.50). Proactive interventions showed a modest benefit (29 trials; n = 17,467; pooled OR = 1.33; 95% CI, 1.21 to 1.47). Multiple proactive callback sessions after contact was initiated by a motivated quitter were most successful (eight trials; n = 18,468; pooled OR = 1.41; 95% CI, 1.27 to 1.57).

The intensity of telephone counseling also improved its effectiveness. In this Cochrane review, the frequency of calls ranged from one to 12 calls over six months. Regression analysis provided significant evidence that higher calling intensity had a greater effect on quit rates. Seven trials of low-intensity interventions with one or two calls showed no significant effect (seven trials; n = 4,225; OR = 1.00; 95% CI, 0.80 to 1.24). Medium-intensity interventions with three to six calls showed a modest benefit (19 trials; n = 11,877; pooled OR = 1.38; CI, 1.23 to 1.55).

Proactive telephone counseling for smoking cessation helps motivated quitters stay abstinent. Three or more calls significantly increase the odds of smoking cessation compared with standard self-help materials or brief physician advice. Clinicians should identify proactive telephone counseling services for smoking cessation and provide this information to patients who want to quit smoking.

ELISSA MEITES, M.D., M.P.H.

DAVID H. THOM, M.D., PH.D.

Source: Stead LF, et al. Telephone counseling for smoking cessation. Cochrane Database Syst Rev 2006;(3):CD002850.

REFERENCE

1. Ossip-Klein DJ, McIntosh S. Quitlines in North America: evidence base and applications. Am J Med Sci 2003;326:201-5.

This clinical content conforms to AAFP criteria for evidence-based continuing medical education (EB CME). See Clinical Quiz on page 619.

The series coordinator for AFP is Clarissa Kripke, M.D., Department of Family and Community Medicine, University of California, San Francisco.

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