Control of bias in randomized controlled trials published in prosthodontic journals

STATEMENT OF PROBLEM

Randomized controlled trials (RCTs) have become the gold standard for evaluating the effectiveness of treatment interventions. If not properly controlled, bias in the design of trial methodology can affect the validity of the study results.

PURPOSE

The purpose of this investigation was to assess the methodological quality of RCTs published in 3 prosthodontic journals over a 10-year period.

MATERIAL AND METHODS

Issues of The International Journal of Prosthodontics, The Journal of Prosthetic Dentistry, and The Journal of Prosthodontics published between 1988 and 1997 were searched manually to identify RCTs. Specific inclusion and exclusion criteria were established to identify articles about studies that qualified as RCTs. Two independent reviewers evaluated all qualified RCTs on the basis of how potential sources of bias in the trial methodology were controlled. Three areas-control of bias at entry, control of bias in assessment of outcome, and control of bias after entry-were evaluated with a scheme developed through the Cochrane Collaboration. A score of 1 or 0 was assigned for each of the 3 potential sources of bias, with the maximum quality score for an RCT being 3 (good bias control) and the minimum 0 (poor control). Frequencies were calculated for each dimension of trial methodology and overall quality scores of the RCTs.

RESULTS

Sixty-two RCTs were identified from 3631 articles screened. The method of randomization was explicit in only 47% of the RCTs. Forty percent of RCTs incorporated blinding in the assessment of outcome, and 76% accounted for all subjects at the end of the study. Overall quality scores revealed that only 16% of RCTs attempted to control bias in all 3 areas examined. Forty percent were deficient in 1 area, 34% were deficient in 2 areas, and 10% were deficient in all areas examined.

CONCLUSION

The quality of RCTs published in prosthodontic journals may be improved by minimizing potential sources of bias and adequately reporting trial methodology.

Immunization recall: effectiveness and barriers to success in an urban teaching clinic

OBJECTIVE

To examine effectiveness of immunization recall in an urban pediatric teaching clinic and to identify barriers to recall effectiveness.

DESIGN

Randomized, controlled trial. Children aged 5 to 17 months who were not up to date (UTD) with recommended immunizations were identified and assigned to intervention (n = 294) or control groups (n = 309). The intervention consisted of a mailed postcard and up to 4 telephone calls. Two months after intervention, UTD status, visit, and probable missed opportunity rates were assessed.

RESULTS

Of the intervention group, 30% could not be reached. In 12-month-old children in the intervention group compared with those in the control group, there was a trend toward higher UTD rates (51% vs 39%, P =.07) and a higher proportion of UTD children receiving immunizations as opposed to getting more complete documentation (25% vs 10%, P =.005). Similar differences between intervention and control children were not seen in the 7-month and 19-month age categories. More children in the intervention group had a health maintenance visit (17% vs 11%, P =.03). Of children in the intervention group who were seen when not UTD, 17 of 24 (71%) of those seen for an illness visit and 5 of 24 (21%) of those seen for health maintenance probably had missed opportunities to be immunized.

CONCLUSIONS

Recall efforts were partially successful but were undermined by inability to reach the clinic population, poor documentation of immunizations, and missed opportunities.

Treatment of hepatitis C virus and HIV coinfection: the road less traveled

The use of HAART for HIV infection has significantly reduced morbidity and mortality secondary to AIDS-related opportunistic infections. In hepatitis C virus (HCV)-HIV-coinfected patients, progression to AIDS, cirrhosis, and liver failure from HCV infection has become an important issue. Liver disease caused by chronic HCV infection has become the second leading cause of death in some HIV-infected populations. HIV infection is not a contraindication to HCV infection therapy. Several clinical studies have borne out that HCV infection can be safely and successfully treated in HIV-HCV-coinfected patients. These patients should be evaluated and offered anti-HCV treatment as clinically indicated.

Role of iron in estrogen-induced cancer

Redox cycling of catecholestrogen metabolites between quinone and catechol forms is a mechanism of generating potentially mutagenic oxygen radicals in estrogen-induced carcinogenesis. Consistent with this concept, multiple forms of oxygen radical-generated DNA damage are induced by estrogen in cell-free systems, in cells in culture and in rodents prone to estrogen-induced cancer. Metal ions, specifically iron, are necessary for the production of hydroxy radicals. Iron has not received much attention in discussions of estrogen-induced carcinogenesis and human hormone-associated cancer, and is the focus of this review. An elevated dietary iron intake enhances the incidence of carcinogen-induced mammary cancer in rats and estrogen-induced kidney tumors in Syrian hamsters. Estrogen administration increases iron accumulation in hamsters and facilitates iron uptake by cells in culture. In humans, elevated body iron storage has been shown to increase the risk of several cancers including breast cancer. A role of iron in hormone-associated cancer in humans offers attractive routes for cancer prevention by regulating metal ion metabolism and interfering with iron accumulation in tissues.

Effect of thimerosal recommendations on hospitals' neonatal hepatitis B vaccination policies

We describe neonatal hepatitis B virus (HBV) vaccine policies in Colorado before and after thimerosal recommendations, plans for use of thimerosal-free HBV vaccine, and nurses' awareness of high-risk criteria for HBV vaccination. The results suggest that fewer neonates are receiving HBV vaccine at birth hospitals.

Barriers to enrollment in a state child health insurance program

OBJECTIVE

To identify barriers to enrollment into Colorado's Child Health Insurance Plan (CHP+) for non-Hispanic (NH), Hispanic (H), and uninsured families.

DESIGN

Telephone survey of 1) random samples of families who requested an application but did not complete it (N = 273 NH, N = 159 H) and 2) families with uninsured children identified by random-digit-dial statewide surveys (N = 165).

RESULTS

Major reasons for not enrolling included 1) got other insurance (NH 16.5%; H 27.2% P <.01), 2) thought household income was too high to qualify (NH 21.0%; H 11.9% P =.01), and 3) paperwork (NH 13.4%; H 14.7%, P = NS). Of those who thought their income was too high (N = 76, 17.6%), 58.5% appeared eligible based on reported income. Of uninsured families, only 41.7% had heard of CHP+. Of those who had never applied, major remediable reasons included not knowing enough about the program (20.9%) and thinking household income was too high (9.3%).

CONCLUSIONS

Effective marketing and education to increase awareness of CHP+ and ensure understanding of eligibility are critical to the success of the program.

Transcatheter coil closure of a right pulmonary artery to left atrial fistula in an ill neonate

Although rare, a congenital direct fistula connection between the proximal right pulmonary artery and the left atrium can present as cyanosis in the newborn. We report the first case in which catheter-based coil closure of such a fistula in a neonate resulted in rapid clinical improvement, obviating the need for surgical repair.

An unusual case of impalement injury to the urinary bladder

Isolated impalement injury to the urinary bladder is a rare occurrence. We present a case in which the delay in the diagnosis reveals the potential pitfalls in the management of such injuries.

Antenatal dexamethasone and the growth hormone-insulin-like growth factor axis

Dexamethasone administration has marked effects on the growth hormone-insulin-like growth factor axis (GH-IGF) in animal and human studies. During pregnancy in the rat, it is associated with fetal growth restriction due to inhibition of IGF bioactivity. In the human only repeated dosages have been associated with fetal growth restriction. The aim of this study is to test the hypothesis that antenatal dexamethasone administration to pregnant women is associated with reduced activity of the GH-IGF axis. To achieve this blood samples were taken from 12 pregnant women pre- and at 24 h and 48 h after dexamethasone administration. In these samples GH, IGF-I, IGF bioactivity and IGF binding protein (IGFBP)-3 protease activity were measured. In view of the interaction between insulin and the GH-IGF axis, glucose and insulin concentrations were also measured. There were no significant differences between the concentrations of GH, IGF-I, IGF bioactivity and IGFBP-3 protease activity before and after dexamethasone. The concentrations of glucose and insulin were significantly higher at 24 h, but not 48 h post-dexamethasone. It is concluded that a single antenatal course of dexamethasone does not alter the GH-IGF-I axis in pregnant women at the time points studied.

Assessment of MEDLINE search strategies for randomized controlled trials in prosthodontics

PURPOSE

The purpose of this study was to evaluate the sensitivity, specificity, and precision of MEDLINE search strategies for detecting randomized controlled trials (RCTs) in prosthodontics.

MATERIALS AND METHODS

A list of RCTs was obtained by hand-searching the International Journal of Prosthodontics, Journal of Prosthetic Dentistry, and Journal of Prosthodontics published between 1988 and 1997. RCTs identified served as the "gold standard" with which different MEDLINE search strategies were compared. Subject headings, keywords, MEDLINE checktags, publication types, and combinations thereof were used, and their results were compared with the "gold standard".

RESULTS

Sensitivity ranged from 9% to 67%, specificity was at least 96% for all searches, and precision ranged from 22% to 59%. The most productive searches were by publication type clinical trial and publication type randomized controlled trial. Combining search terms did not improve sensitivity for detecting RCTs published in prosthodontic journals (p > .10).

CONCLUSION

These findings support the need for more detailed reporting of trial methodologies to facilitate accurate indexing of prosthodontic articles in MEDLINE.

Dysregulation of the insulin/IGF binding protein-1 axis in transgenic mice is associated with hyperinsulinemia and glucose intolerance

The insulin/IGF binding protein-1 (IGFBP-1) axis is important in coordinating insulin- and IGF-mediated regulation of glucose metabolism and glycemia. Dysregulation of the axis may play a role in the pathophysiology of disorders of insulin deficiency and resistance. We have investigated this hypothesis by generating transgenic mice that overexpress hIGFBP-1. To study the axis in its true physiological context, we used a human (h) IGFBP-1 cosmid clone so that transgene expression is responsive to normal hormonal stimuli. hIGFBP-1 mRNA is expressed in a tissue-specific fashion, and measurement of serum protein levels by specific immunoassay indicates normal physiological regulation in response to fasting/feeding and appropriate post-translational modification as indicated by the detection of phosphorylated and nonphosphorylated isoforms of the protein. The hypoglycemic response to exogenous IGF-I is attenuated in transgenic mice. Transgenic mice exhibit an enhanced insulin secretory response to a glucose challenge, although basal and stimulated blood glucose levels are similar to controls. There is a sexual dimorphism in phenotypic expression: male transgenic mice had higher stimulated glucose and insulin levels than did females. Transgenic mice exhibit fasting hyperglycemia and hyperinsulinemia and glucose intolerance in later life, indicating an age-related decline in glucocompetence. These findings demonstrate the importance of the normal inverse relationship between serum insulin and IGFBP-1 levels in glucoregulation and that sustained dysregulation of the insulin/IGF-I/IGFBP-1 axis is associated with impaired glucose tolerance and abnormalities of insulin action.

Use of recombinatory PCR to insert subtle genetic markers into Moloney murine leukemia virus-based retroviral vectors

As tools to examine template switches and recombination events during the process of reverse transcription, two nearly identical Moloney murine leukemia virus-based (MoMLV) retroviral vectors were constructed using the technique of recombinatory polymerase chain reaction (PCR). The experimental vectors designed for this study were based on the well-characterized LN series vectors. The protein coding regions normally present in the retroviral genome have been replaced by the coding regions for two drug resistance markers, neomycin phosphotransferase (Neo) and hygromycin phosphotransferase (Hyg). With only one functional drug resistance gene in each vector, the individual vectors as well as recombination events between them can be followed by phenotypic selection. Utilization of recombinatory PCR allowed the insertion of very subtle nucleotide changes resulting in a series of restriction site polymorphisms in the two retroviral vectors. The ability to create these subtle mutations in specific locations of these retroviral vectors allowed the utilization of naturally occurring areas of variability in the vectors and avoid regions important for replication.

Paternal hamsters mechanically assist the delivery, consume amniotic fluid and placenta, remove fetal membranes, and provide parental care during the birth process

We report the first description of a male mammal behaviorally participating in the birth of his young. Djungarian hamsters, Phodopus campbelli, are naturally biparental and males contribute to pup survival and growth through direct paternal care and indirect effects on maternal physiology. Males of the closely related Siberian hamster, P. sungorus, have only seasonal opportunities to interact with pups and neither contribute to pup survival and growth nor provide extensive paternal care under laboratory conditions. Male P. campbelli undergo a series of hormonal changes prior to the birth of their first litter which are not shared with P. sungorus males and may "prime" males to express paternal behavior. We hypothesized that P. campbelli males would behave paternally on first contact with pups during the birth process, whereas P. sungorus males would not. In addition to showing paternal behavior toward neonates, male P. campbelli licked amniotic fluid before the birth, mechanically assisted the delivery, opened an airway by clearing the nostrils (so that pups flushed red with oxygenation), licked and sniffed pups in the moments and minutes after birth to clean the pups of membranes, and ate the placenta. None of these behaviors were observed in P. sungorus. We anticipate that P. campbelli will not be the only species with highly developed paternal behavioral repertoires during the birth.

Nasogastric feeding enhances nutritional status in paediatric liver disease but does not alter circulating levels of IGF-I and IGF binding proteins

OBJECTIVE

Complications of childhood cirrhosis include abnormal growth and malnutrition, associated with abnormalities in circulating IGFs and IGFBPs. Controlled studies suggest that intensive enteral feeding enhances nutritional status. The aim was to ascertain whether nasogastric feeding improves nutritional status in clinical practice and to assess the effect of feeding on serum IGF-I and IGFBPs.

PATIENTS

Thirty-three children (median age 0.6 years) with biliary atresia and failure to thrive who were treated with nasogastric feeding.

MEASUREMENTS

Height, weight and triceps skin fold thickness were measured prior to feeding and regularly for 1 year or until feeding was stopped. Serum IGF-I and IGFBPs were measured by immunoassay at the same intervals.

RESULTS

The median duration of feeding was 3.7 months. Twenty-two stopped feeding after liver transplantation, while 10 stopped electively and 1 boy died. Before feeding, the children were losing weight and height centile. Triceps skin fold thickness, weight and height SD scores improved with feeding. Baseline serum IGF-I and IGFBP-3 were low, while IGFBP-1 and IGFBP-2 were raised. IGF-I and IGFBP-1 did not change with feeding. IGFBP-2 fell and reached a nadir by 3 months, while IGFBP-3 rose temporarily for 4-6 weeks.

CONCLUSIONS

Nasogastric feeding improves body composition in paediatric liver disease but circulating IGF-I and IGFBPs remain abnormal and do not play a major role in mediating these changes. This does not exclude a paracrine or autocrine effect of IGF-I.

Developing a register for randomized controlled trials in prosthodontics: results of a search from prosthodontic journals published in the United States

STATEMENT OF PROBLEM

Treatment decisions are often made despite absence of evidence from well-conducted clinical trials. Conclusions about treatment efficacy derived from nonexperimental approaches often overestimate treatment effect. Randomized controlled trials (RCTs) provide the most reliable basis for evaluating effectiveness of treatment interventions.

PURPOSE

This study attempted to identify and catalog RCTs in prosthodontic journals published in the United States as an initial step in creating a register of clinical trials that would be a resource in setting up systemic overviews of prosthodontic literature.

METHODS

The International Journal of Prosthodontics, The Journal of Prosthetic Dentistry, and The Journal of Prosthodontics published between 1988 and 1997 were searched manually to identify clinical trials. Clinical trials had to meet the following criteria for inclusion in the register: the trial must involve human subjects, must include at least 2 treatment groups, and treatment group allocation must be randomized.

RESULTS

A total of 3,631 articles in 196 journal issues were screened. Sixty-two articles (1.7%) met the minimum criteria for inclusion in the RCT register.

CONCLUSION

Given the lack of randomized controlled trials in prosthodontic journals, a concerted effort by the organized prosthodontic community should be made to screen national and international journals and contribute to the development of a register of randomized controlled trials relevant to prosthodontics.

Emergency department presentation of idiopathic intracranial hypertension

Idiopathic intracranial hypertension (IIH), or pseudotumor cerebri, is a syndrome characterized by an elevated intracranial pressure in the absence of a focal lesion, infective process, or hydrocephalus. New onset IIH may present to the emergency department in a variety of ways. To describe the etiologic associations and clinical features in this disorder, we performed a retrospective analysis of consecutive emergency department patients with new onset IIH during the calendar years 1987-1996. A total of 52 patients met all study criteria. The mean patient age was 27+/-8.9 years; the female-to-male ratio was 7:1. An etiologic association could be identified in 85% of cases and included obesity, hypertension, drugs, endocrine, and systemic disorders. Headache was a dominant complaint in most patients (48/52) and associated with dizziness, nausea, and/or visual complaints. Fourteen patients (27%) were not diagnosed on their initial ED visit and were more likely to have atypical clinical features (71% vs. 24%; P = .004). Atypical features included paraesthesias, neck/back pain, unilateral headache, vertigo, and nystagmus. Papilledema, the ophthalmoscopic hallmark of IIH, was not detected initially in 11 patients (21%). These results suggest that IIH is a relatively uncommon neurological illness that may have a variety of causes. The emergency department diagnosis may be complicated by atypical clinical features and a lack of detectable papilledema.