Estimating sample sizes for binary, ordered categorical, and continuous outcomes in two group comparisons

Sample size calculations are now mandatory for many research protocols and it is a main question before accomplishing a research. This paper outlines the ways of calculating sample sizes in clinical trial studies with two groups: binary, ordered categorical, and continuous outcomes. In each section a table for calculating sample size and working examples are given

[ role of health beliefs in preventive behaviors of individuals at high-risk of type 2 diabetes mellitus]

Diabetes mellitus is an important health problem that leads to severe complications, is the cause of early death, and is showing an increase in frequency. Development of positive health behaviors is extremely important for prevention of diabetes in at high-risk individuals. This study aims to identify the relationship between health beliefs and diabetes preventive behaviors in individuals at high-risk for developing type 2 diabetes mellitus in Taft city. A study using the Health Belief Model [HBM] framework was undertaken with 114 subjects of both genders aged 30 years and above from three urban health centers who were diagnosed as at high risk for type 2 diabetes during the screening program. Research tool was a 66-item questionnaire. Data was analyzed with descriptive statistics, Spearman correlation and Mann-Whitney U-test. Of the total, 29.8% of subjects were male and 70.2% were female. Regarding education, 68.4% of the subjects had not completed high school and 89.4% of them was married. Mean score of knowledge and preventive behaviors was 5.80 +/- 2.87 and 5.41 +/- 2.83, respectively such that subjects scored 30.05% of maximum obtainable score of preventive behaviors. There were significant correlations between preventive behaviors and perceived susceptibility, r=0.243[P<0.009], perceived severity, r=0.312 [P<0.001], perceived barrier, r=0.245 [P<0.006] and perceived self-efficacy, r=0.497 [P<0.001]. Preventive behaviors among the subjects at high-risk for developing type 2 diabetes despite the presence of risk factors was poor due to lack of susceptibility, severity, barriers and self-efficacy perception

Renal scar formation in children with recurrent urinary tract infections

Reports of renal scar formation in children even in the absence of vesicoureteral reflux necessitates studying other causes of this major complication. The present study mainly focuses on the role of recurrent urinary tract infections [UTI] in renal scar formation. The records of 53 patients with recurrent UTI and the data on their regular follow up visits were reviewed. Renal scar formation was confirmed by dimercapto-succinic acid [DMSA] scan. DMSA scan, done at a mean age of 8.31 years, revealed renal scar formation in 12 cases [22.44%]. Seventy-five percent of the patients with scar formation and 80.5% without scar were older than 3 years at the time of the first documented UTI. The etiologic organism was found to be Escherichia coli in 89.2% of the infections in the scar forming versus 78.8% in the non-scar forming group. In the presence of normal urinary tract anatomy, recurrent UTI can be a significant cause of renal scar formation in children

Cost benefit of the routine urinalysis

In the present health care environment, cost-benefit analysis is extremely important. In this screening program, the minimal cost of screening dipstick urinalysis in 1601 asymptomatic school children was determined. The process of screening was similar to all the studies. The minimal cost utilizing 3 general physicians was calculated. Costs were determined by using current charge for supplies ordered to perform tests, charges for tests performed by a commercial laboratory, and the cost of a final evaluation by a pediatric nephrologist. Initial abnormal urinalysis was found in 4.7% [76/1601] of patients. Upon retesting 1.37% [22/1601] of patients were calculated to have a persistent abnormality. The calculated cost was 1/530/000 Rials [164.5 $] to initially screen all 1601 patients with a dipstick urinalysis or 850 Rials [0.09 $] per patient. The calculated cost to evaluate the 22 patients with any persistent abnormality on repeat dipstick urinalysis was 246/840 Rials [26.5 $] or 11.220 Rials [1.2 $] per patient. This is the calculated cost for a single screening of 1601 asymptomatic pediatric patients. Multiple screening dipstick urinalysis in asymptomatic pediatric are costly and should be discontinued. We purpose that a single screening dipstick urinalysis be obtained at school entry age, between 6 and 7 years old, in all asymptomatic children

Study of the effeciency of volcanic rock bed filters in enhanced ammonia and fecal coliform removal from khoy wastewater treatment plant

Ammonia and fecal coliform removal from wastewater is of high necessity because of its inappropriate impact on environment where wastewater accumulates. Aerated lagoons as well as polishing ponds would not be able to decrease ammonia and fecal coliforms in an efficient way. Different procedures are usually applied for the removal of ammonia and fecal coliform in wastewater treatment plants. In this study, effluent of polishing pond in wastewater treatment plant of Khoy in North-West Azerbaijan with three different loading flow rates [0.3, 0.6, 0.9 m[3]/m[3].d] was entered into the rock filter with volcanic rock bed, rock diameter size of which was 50 mm. To determine the efficiency of rock filter in any loading flow rates, 10 samples of influent and effluent were taken. The results showed that mean of effluent ammonia level changed from 16.8 to 4.8 mg/1 and effluent fecal coliform from 1.9xl0[4] MPN/l00ml to SJxl0[3] MPN/lOOml. Rock filter efficiency for Ammonia and fecal coliform removal of pond effluent were 71.4% and 70% respectively. Ammonia and fecal coliform decreased in all loading flow rates but in the first rate changes were more remarkable than the two other rates. As loading flow rate increased, removal efficiency decreased. This is probably due to low hydraulic retention time that resulted in decreasing nitrification. Thus it is concluded that rock filter here presented has better efficiency than what were used in similar studies

Evaluating the characteristics and structure of dentistry graduated students theses in Shahid Sadughi University of Medical Sciences

Theses are considered as one of the main sources of information. The aim of this study was to evaluate the characteristics and structures of students' theses as well as their research methodology. In this descriptive study, all dentistry students' theses from the year 1998 till the year 2004 [176 theses], were investigated based on the aspects of thesis' structure, research methodology, and the results. Thirty seven point five percent of theses were descriptive, 17.6% were experimental, 16.5% were descriptive-inferential, 6.8% were inferential, and 8% were clinical trials studies. Ten point two percent of the theses gained excellent quality score, 64.8 percent gained good quality score, 24.2 percent gained moderate quality score, and 0.6 percent gained poor quality score in writing and research methodology. More supervision should be placed on theses quality by supervisors. It is also suggested to encourage students towards inferential and experimental studies. Moreover, the need to train students in regard to research methodology and statistics is emphasized and it is recommended to develop a comprehensive guideline for writing theses

Effectiveness of Lawsonia inermis extract on cutaneous leishmaniasis lesion in BALB/c mice

Henna [Lawsonia inermis] leaf has long been used for industrial, commercial and medical purposes. The present study was performed to determine the efficacy of henna on cutaneous leishmaniasis lesion in BALB/c mice. Sufficient amount of henna leaves were prepared, grounded, and dissolved in 80% alcohol and the extract was prepared by percolation method. The dry extract was sterilized and prepared in ointment base at 40, 60, and 80% concentrations. At the same time, 40 mice [BABL/c, 8 weeks old] were infected by Leishmaniasis Major [MRHO/IR/75/ER] through the injection of 0.1 ml promastigotes subcutaneously in their tail base. Then animals were divided into one control group [without receiving any drug] and three experimental groups receiving respectively 40, 60, and 80% concentrates of henna extract every two days and immediately after the appearance of the lesion. Weekly monitoring of weight and lesion diameter was recorded. Data analysis was done through SPSS software. In regard to the mean weight the groups receiving 40% extract and 60% extract showed significant difference with each other [P = 0.000] but not with the group receiving 80% extract. There was also no significant difference between control group and case groups in mean weight. Lesion diameter in 40% extract group had significant difference comparing to the control group and 60% and 80% extract groups. Mean lesion size of the mice receiving 40% henna extract compared with mice receiving 60% extracts showed significant difference [P = 0.000]. Totally, henna extract reduced the rate of weight decrease but it was not significant. However, the mean lesion size of mice receiving'henna extract was significantly reduced as compared with that of control group

[Assessment of two evaluation methods in cognitive domain for dental students in orthodontic department: CBT versus PBT]

The computer-based testing [CBT] is now an accepted tool for assessment in fields of higher education but there is a lack of empirical research in the usefulness of computer in evaluation of medical sciences. The purpose of this study was to compare the dental students' performance test scores with computerized and paper-based testing [PBT]. This analytical study was carried out on 46 dental students at orthodontic department of Yazd University of medical sciences in 2004. The new software with selected questions and commercial paper-based testing were used for CBT and PBT, respectively. Analysis of data was carried out using t-test and correlation test of Spearman. There was a significant correlation between CBT and PBT for students' scores [r=0.6, p=0.000], however, no statically significant correlation was found between mean scores obtained for CBT and PBT. Our results indicated that the CBT could be reliably used for the purpose of student ranking but care should be taken in using it for grading

[Comparison of life expectancy levels of men and women in Yazd province in 1996 and 2003]

Life expectancy at birth is an indicator of the mean age that a new born will live and this indicator is one of the criteria for evaluation of the heath, economic and social conditions. In this descriptive study, the life expectancy table of men and women in Yazd state is calculated on the basis of probability of death in different age groups during the years 1996 and 2003. In 1996, the life expectancy at birth of women and men were 74.5 and 71.9 years, respectively, while these figures in2003 were 79.5 and 71.9 years, respectively. In 1996, the most and the least life expectancies were in Taft and Mehriz, while in 2003, the most and the least life expectancies were in Mehriz and Yazd city. The results show that the life expectancies of both man and women has increased in Yazd and this increase was more marked in women than men

[Comparison of topical EMLA cream with oral glucose on pain reduction at venipuncture in ichteric newborns]

A number of studies have shown that orally administered sweet-tasting solutions reduce signs of pain during painful procedures. The topical anesthetic cream EMLA has recently been shown to be safe for use in neonates. This study compared the pain-reducing effect of EMLA cream with that of orally administered glucose during venipuncture in newborns. A randomized controlled, double-blind study including 220 newborns undergoing venipuncture for clinical purposes was performed. One hundered and six newborns received EMLA on the skin and orally administered placebo [sterilized] and 114 received glucos- 30% orally and placebo [Vit A+D] on the skin. Symptoms associated with pain at venipuncture were measured with the Neonatal/ Infant Pain Scale [NIPS]. Crying time was recorded. The results showed that the NIPS scores were significantly lower in the glucose group [mean: 1.89] compared to the EMLA group [mean: 2.81]. The duration of crying in the first 2 minutes was significantly lower in the glucose group [median=2 seconds] than in the EMLA group [median=9 seconds]. There were significantly fewer patients in the glucose group who were scored having pain [defind as NIPS scores above 3], 12.3% compared with 29.2% in the EMLA group. We found that glucose is effective in reducing symptoms associated with pain from venipuncture in newborns. Our results showed that glucose is more effective than the local anesthetic cream EMLA

survey of the educational needs on hygenic problems of puberty in girls

In this descriptive study, 250 students aged 12-14 were studied by random sampling. Data were gathered by interview and questionnaire. The results indicated that the subjects possessed a poor knowledge on puberty health [mean of 3.61 from 10]. The most important sources of acquiring relevant information were: the subjects, mothers [68.4], friends [11.2], health instructors [12%], books and journals [4.4%] and others [4%]. There was a relationship between the students, age and knowledge [p=0.0001]. 41.2% of the students enjoyed a poor knowledge on menstruation. The age average of the girls for menarche was 12.5. The finding suggests instructing mothers in the first place to convery useful and proper information to their offspring. Also instructors can have a forceful role in conveying the related information. Incorporating the information into the students' textbooks before puberty can also yeild useful results

Clinical evaluation of caries removal in primary molars using Carisolv and rotary instruments

Employing conservative procedures and considering patient comfort are of great importance, especially for dental treatment in paediatric patients. The aim of this study was to compare the efficacy of the Carisolv system with high-speed excavation of caries using rotary instruments, in primary molars. Twenty-five children with a mean age of 7.02 +/- 1.64 years were included in this clinical trial. Each patient had at least two contralateral primary molars with comparable caries and approximately equal-size access to lesions [N=50]. Caries were removed using the Carisolv system and rotary instruments. The efficiency of caries removal was judged on the basis of clinical criteria. Length of working time, need of local anesthesia, and level of patient cooperation were recorded for both methods. Statistical analysis was performed using the MCNemar and paired t-tests. The Carisolv and rotary systems removed 88% and 100% of the caries, respectively [p=0.0001], Working time with the chemomechanical method was prolonged when compared with the mechanical method [P =0.0001], but it did not negatively affect the childrens' cooperation. 92% of the patients found Carisolv treatment more acceptable than the highspeed excavation system. Furthermore, the chemomechanical method reduced the need for administration of local anesthesia for cavity preparations [0% versus 28%] [P=0.002]. Carisolv is an effective clinical alternative treatment for the removal of caries in primary molars. It is also more conservative of dental tissue and appears to be more comfortable for most patients

Urinary tract infection in infants and children with diarrhoea

To determine when children with acute diarrhoea should be investigated for urinary tract infection [UTI], we studied 120 patients and 120 healthy age- and sex- matched controls aged 4 weeks to 5 years. In those with positive or suspicious urine cultures, bacteriuria or pyuria, urine culture was repeated. We detected UTI in 8 patients [all < 2 years] and 1 boy in the control group. In those with UTI, invasive diarrhoea was observed in 1, fever in 7 and vomiting in 5 patients. In children with acute diarrhoea, investigation for UTI is only recommended for febrile, female infants aged 5- 15 months

Bone mineral density in children with relapsing nephrotic syndrome

Given the high relapse rate of disease in children with steroid dependent nephrotic syndrome and the osteoporotic effect of long periods of steroid therapy, this survey was performed to find the bone mineral status of these patients. Bone mineral density and content [BMD and BMC] were measured using Dual energy X-ray absorptiometry in 37 nephrotic children, six girls and 31 boys aged from four to 21- yrs, as patient group and 37 age and sex-matched healthy individuals as control group. Historical data were collected by chart review. As compared to the control group, the patients were shorter in stature. The percentage of BMC of lumbar and BMD of femoral bones of the patients was significantly lower than control group. According to the Warner method, 12% of the patients were osteoporotic and the BMD of their femoral and lumbar bones was inversely correlated with cumulative steroid dose. Bone loss can occur in some steroid-dependent nephrotic patients, especially those with low age of onset and those with longer duration of the disease and higher cumulative dose of steroid. Therefore, measurements of BMD and BMC could be recommended, at least, for the selected patients

[Comparison of Ag NORs count in exfoliative cytology of normal oral mucosa in smokers and non-smokers]

A strong causal relationship exists between cigarette smoking and development of oral squamous cell carcinoma, so oral screening using exfoliative cytology has been recommended to facilitate the early diagnosis of cellular alterations in oral mucosa and silver staining [AgNOR technique] has been proven to be of value in the detection of incipient cellular alterations. The purpose of this study was to compare the argyrophilic nucleolar regions [AgNORs] count of cells collected from normal mucosa of cigarette smokers with that obtained from non- smokers. In this cross-sectional study, cytologic smears of normal tongue, buccal mucosa and floor of the mouth from 19 smokers and 19 non- smokers were stained for AgNORs. The AgNORs count was established on 100 cells. The count value of groups were compared and analyzed using the Levens, Paired T, Student and Factorial tests. Using P<0.05 as the limit of significance. The AgNORs were round and had a clustered distribution in both groups. The mean AgNORs count was statistically higher in cells of smokers than non- smokers [P<0.05]. There was a significant difference between smears from the floor of the mouth and other anatomical sites in both groups. In this study, no correlation was found between AgNORs count and gender. Analysis of AgNORs suggests that there might be a correlation between the smoking habit and an increased rate of cellular proliferation in the oral mucosal cells

Effect of betamethasone with or without gentamicin on renal scarring in rat model of pyelonephritis

To evaluate the effect of betamethasone in preventing renal scarring in rat model of pyelonephritis. Material and Sixty three female Sprague-Dawley rats were divided into seven equal groups [A-G]. After exposing the left kidney under general anesthesia, direct inoculation of colonies of mannose-sensitive E.coli was done in groups C-G and normal saline in group B. No injection was done in group A. After 48 hours of bacterial inoculation, intramuscular [IM] injections of gentamicin [3 mg/kg/ day for 10 days] was used in groups C, E and F. Betamethasone [0.3 mg/kg/day IM] was used after two days [group D and E] and 5 days [group F] of bacterial inoculation. Normal saline as daily IM injections for 10 days in group B and no IM injection in group G was done. After 8 weeks of bacterial inoculation, the rats were sacrificed and the volume of renal scar was determined using a point- counting technique. Changes in the weight and volume of the kidneys were not statistically significant. No scar was detected in group A, but all the other groups with intrarenal injections [including group B with no bacterial inoculation] had scarring. The volume density and absolute volume of the scar in groups C-G were significantly more than group B [p < 0.001], but no statistically significant difference was observed in groups C-G. Betamethasone with or without gentamicin, when used 48 hours or more after induced pyelonephiritis is not effective to prevent renal scar

Nephrotic syndrome in a girl with vesicoureteral reflux and situs inversus

In this case report a five year old girl is presented with steroid-responsive nephritic syndrome who had bilateral Vesicoureteral Reflux [VUR] and situs inversus. A combination of situs inversus, nephritic syndrome and VUR has been reported previously

Primary vesicoureteral reflux in children in southern Iran

Experience with vesicoureteral reflux [VUR] differs in different centers and there is plenty of controversies. To evaluate the outcome of primary VUR complications and the rate of recurrence of UTI. In a retrospective study, the medical charts of all infants and children with primary VUR who were followed up by one nephrologist were reviewed. During 16 years, 271 patients [226 females, 45 males] with 401 refluxing ureters were followed up as primary VUR. The patients' age at diagnosis was 4 days to 16 years [Mean: 4.4 years] and the mean duration of follow-up was 4.2 years. Urinary tract infection [UTI] was the presenting symptom in 97% and fever was recorded in 30% of cases. Frequencies of different grades of VUR at initial investigation were 6.5%, 52%, 23.4% and 18.1% for grades I to IV, respectively. The responsible microorganism in 90% of the first episodes of UTI was E. coli. Scarring or small size kidney was present in 63 patients. Recurrence of UTI in VUR of grades I to IV, were 68.7%, 51%, 60.1% and 46.8%, respectively. Follow-up voiding cystourethrogram revealed resolution of VUR in 52%, improvement in 31%, no change in 11%, and deterioration in 6%. Complications such as chronic renal failure, hypertension and renal tubular acidosis were observed in 11, 10 and 9 patients, respectively. Symptomatic primary VUR is more common and has better prognosis in girls. Recurrence of UTI is not related to the grade of VUR

Relapse Rate in Daily Single-Dose Prednisolone Therapy for Children with Primary Nephrotic Syndrome

Most current references recommend divided doses of prednisolone for the initial treatment of idiopathic minimal change nephrotic syndrome in children, with relapse occuring in the majority of them, but there is little experience concerning single-dose prednisolone therapy, especially considering the relapse rate. In this prospective study on 36 consecutive children with primary nephrotic syndrome, prednisolone [2 mg/kg/day] was used as a single daily dose in 17 patients [SD group], or divided into 3 doses in 19 cases [DD group] who were randomly selected, and relapse rates were compared. The mean age of the patients was 6 years [range 15 months-13 years] and there was no statistically significant difference between the two groups considering age, sex, clinical presentation, laboratory findings at the time of admission and prednisolone side effects. After 4 weeks of full dose prednisolone therapy, the drug was changed to 2 mg/ kg as a single dose every other day in both groups, irrespective of the response. During the third month of therapy, the drug was reduced to 1 mg/kg every other day and it was discontinued after 4 weeks. Relapse rate was compared in steroid responsive patients in both groups [14 in the SD and 11 in the DD group] who were matched for age, sex and paraclinical findings. During the first year of follow-up, in those who were initially steroid responsive, 2 patients in the SD and 6 in the DD group had no relapse. The number of total relapses/year in the SD and DD group were 19 for 12 patients and 8 for 5 patients respectively [p<0.02]. In conclusion, daily single-dose prednisolone therapy in childhood nephrotic syndrome can be effective for induction of remission and is tolerated well by patients but increases the relapse rate significantly