Biomechanical properties of tendons during lower-leg lengthening in dogs using the Ilizarov method

Ten dogs were provided with a circular fixator. Segment resection of the fibula and tibial osteotomy in the right lower leg was performed. 5 days after surgery, a lengthening of the right lower leg by 2.5 cm was performed on 6 dogs using a distraction rate of 0.5 mm, twice per day. 3 dogs with leg lengthening and 2 dogs of the control group without leg lengthening were sacrificed at the end of the distraction phase of 25 days and the remaining dogs after another 25 days. Postmortally the tendons of the tibialis anterior, extensor digitorum longus, peroneus longus and the achilles tendon were taken from the operated right side and the left non-operated control side and were examined biomechanically in cyclic tests. The control group without lengthening showed no changes in the biomechanical properties in the tendons of either side nor in those of the unlengthened left side of the operated dogs. In contrast the biomechanical tests revealed a marked decrease of the elastic modulus, an increase of distraction length and an increase of modulus reduction on the lengthened side compared to the non-operated left side.

Technical factors in early amniocentesis predict adverse outcome. Results of the Canadian Early (EA) versus Mid-trimester (MA) Amniocentesis Trial

The purpose of this study was to identify risk factors for fetal loss and other pregnancy complications associated with genetic amniocentesis. Data were acquired in the Canadian Early Amniocentesis Trial (CEMAT), a multicentered (12) prospective, randomized trial comparing continuous ultrasound-guided early amniocentesis (EA) and mid-trimester amniocentesis (MA) (CEMAT Group, 1998). Details of the procedure were recorded and analysed by allocation (EA versus MA), operator and centre, and correlated with pregnancy outcome. A total of 62 spontaneous pregnancy losses occurred between the procedure and 20 weeks' gestation among the 3691 patients who received their procedures within the allocated window (EA=53/1916, MA=9/1775). Technical factors correlating with these losses included procedures 'judged to be difficult' by the operator, and post-procedure amniotic fluid leakage or bleeding. Maternal risk factors included maternal hypertension (fetal loss 11. 1 per cent, compared with non-hypertensive women, 2.6 per cent) increased body mass index (BMI) and gravidity of three or greater. Allocation to EA was predictive of fetal loss, as well as failed procedure, multiple needle insertions, amniotic fluid leakage, failed culture and talipes equinovarus, in excess compared with MA. In conclusion, in this large prospective randomized trial evaluating amniocentesis, specific maternal, fetal and procedural variables were found to be predictive of fetal loss and adverse pregnancy outcome. Performing amniocentesis before 13 weeks' gestation (EA) was the major predictive factor for adverse outcome. These data suggest that first-trimester chorionic villus sampling (CVS) and MA will likely remain the invasive procedures of choice for evaluation of fetal karyotype.

Left ventricular mass index increase in early renal disease: impact of decline in hemoglobin

Cardiovascular disease occurs in patients with progressive renal disease both before and after the initiation of dialysis. Left ventricular hypertrophy (LVH) is an independent predictor of morbidity and mortality in dialysis populations and is common in the renal insufficiency population. LVH is associated with numerous modifiable risk factors, but little is known about LV growth (LVG) in mild-to-moderate renal insufficiency. This prospective multicenter Canadian cohort study identifies factors associated with LVG, measured using two-dimensional-targeted M-mode echocardiography. Eight centers enrolled 446 patients, 318 of whom had protocol-mandated clinical, laboratory, and echocardiographic measurements recorded. We report 246 patients with assessable echocardiograms at both baseline and 12 months with an overall prevalence of LVH of 36%. LV mass index (LVMI) increased significantly (>20% of baseline or >20 g/m2) from baseline to 12 months in 25% of the population. Other than baseline LVMI, no differences in baseline variables were noted between patients with and without LVG. However, there were significant differences in decline of Hgb level (-0.854 v -0.108 g/dL; P = 0.0001) and change in systolic blood pressure (+6.50 v -1.09 mm Hg; P = 0.03) between the groups with and without LVG. Multivariate analysis showed the independent contribution of decrease in Hgb level (odds ratio [OR], 1.32 for each 0.5-g/dL decrease; P = 0.004), increase in systolic blood pressure (OR, 1.11 for each 5-mm Hg increase; P = 0.01), and lower baseline LVMI (OR, 0.85 for each 10-g/m2; P = 0.011) in predicting LVG. Thus, after adjusting for baseline LVMI, Hgb level and systolic blood pressure remain independently important predictors of LVG. We defined the important modifiable risk factors. There remains a critical need to establish optimal therapeutic strategies and targets to improve clinical outcomes.

Cytogenetic aspects of the Canadian early and mid-trimester amniotic fluid trial (CEMAT)

Cytogenetic results from a large multicentre randomized controlled study of 2108 amniotic fluids obtained at 11+0-12+6 weeks (EA) and 1999 fluids at 15+0-16+6 weeks (MA) were compared. There was no statistically significant difference in the rate of chromosome abnormalities (EA =1.9 per cent; MA=1.7 per cent) or level III mosaicism (EA=0.2 per cent; MA= 0.2 per cent) between the groups. Level I and Level II mosaicism occurred more frequently in MA. Maternal cell contamination was not significantly different between the groups, but maternal cells only were analysed from one bloody EA fluid. The number of repeat amniocenteses because of cytogenetic problems was 2.2 per cent in the EA group compared with only 0.3 per cent in the MA group. On average, culture of EA fluids required one day more than MA fluids. Although both culture success (97.7 per cent) and accuracy (99.8 per cent) were high for patients randomized to the EA group, routine amniocentesis prior to 13 weeks' gestation is not recommended for clinical reasons including an increased risk of fetal loss and talipes equinovarus.

Predicting the time needed to achieve steady state if absorption and elimination constants are equal

A simple table is derived to facilitate the rapid estimation of the number of dose administrations needed to achieve a certain fraction of the steady-state plasma concentration in the case of one-compartment model with uniform multiple oral dosing and equal absorption and elimination constants.

Behavior of tendons during lower-leg lengthening in dogs using the Ilizarov method

Twenty-two dogs were provided with a circular fixator. Lengthening of the right lower leg by 2.5 cm was performed on 18 dogs 5 days after tibial osteotomy using a distraction rate of 0.5 mm, twice per day. Nine dogs with leg lengthening and two dogs of the control group without leg lengthening were sacrificed at the end of the distraction phase of 25 days and the remaining dogs after another 25 days. Post mortem, the tendons of the tibialis anterior, extensor digitorum longus, peroneus longus, and the Achilles tendon were taken from the operated-on right side and the left nonoperated-on control side and were analyzed histologically. The control group showed no histologic changes in the tendons of either side nor in those of the unlengthened left side of the operated-on dogs. Thirty-three tendons (41%) of dogs with leg lengthening were seen to have undergone histomorphological changes. An increase of the peritendinous connective tissue was seen, combined with chronic inflammatory cell infiltration in the tendons and/or the epitendinous tissues, edema, tendon fragmentation, necrosis, scarring of the tendons with dystrophic calcification and/or ossification, and broadening of the tenosynovial sheath. Furthermore, signs of histoneogenesis with growth in the tendons were found. Degenerative changes occurred far more often in the tendons of the ventral side of the lower leg and a slight pes equinus was regularly observed in the lengthened extremity. Therefore, pes equinus prevention and physiotherapy are important in the therapeutic use of lower-leg lengthening to minimize possible stress-induced damage of the ventral tendons.

Determinants of short- and long-term outcome in patients with respiratory failure caused by AIDS-related Pneumocystis carinii pneumonia

OBJECTIVES

To determine (1) predictors of in-hospital mortality and long-term survival in patients with acute respiratory failure (ARF) caused by acquired immunodeficiency syndrome-related Pneumocystis carinii pneumonia (PCP) and (2) long-term survival for patients with ARF relative to those without ARF.

METHODS

A retrospective medical chart review was conducted of all cases of PCP-related ARF for which the patient was admitted to the intensive care unit of a single tertiary care institution between 1991 and 1996. Data were extracted regarding physiologic scores, relevant laboratory values, and duration of previous maximal therapy with combined anti-PCP agents and corticosteroids at entry to the intensive care unit. Duration of survival was determined by Kaplan-Meier methods from date of first hospital admission and compared for patients with and without ARF.

RESULTS

There were 41 admissions to the intensive care unit among 39 patients, with 56.4% in-hospital mortality. Higher physiologic scores (Acute Physiology and Chronic Health Evaluation II [APACHE II], Acute Lung Injury, and modified Multisystem Organ Failure scores) were predictive of in-hospital mortality. Duration of previous maximal therapy also predicted in-hospital mortality (45% for patients with <5 days of previous maximal therapy vs 88% for those with > or =5 days of previous maximal therapy; P = .03). Combining physiologic scores and duration of previous maximal therapy enhanced prediction of in-hospital mortality. There was no difference in long-term survival between patients with PCP with ARF and those without ARF (P = .80), and baseline characteristics did not predict long-term survival.

CONCLUSIONS

In-hospital mortality of patients with acquired immunodeficiency syndrome-related PCP and ARF is predicted by duration of previous maximal therapy and physiologic scores, and their combination enhances predictive accuracy. Long-term survival of patients with ARF caused by PCP is comparable to that of patients with PCP who do not develop ARF, and determinants of in-hospital mortality do not predict long-term survival.

Predictors of survival and eradication of Mycobacterium avium complex bacteremia (MAC) in AIDS patients in the Canadian randomized MAC treatment trial. Canadian HIV Trials Network Protocol 010 Study Group

OBJECTIVE

To assess the importance of baseline characteristics including medical history, indicators of current disease status, therapeutic drug use, in vitro drug susceptibility, immune status and mycobacterial load on bacteriologic response and survival in HIV-positive patients with Mycobacterium avium complex (MAC) bacteremia.

DESIGN

An observational substudy of an open-label randomized controlled trial of two alternative therapeutic regimens for MAC.

SETTING

Twenty-four hospital-based HIV clinics in 16 Canadian cities.

MAIN OUTCOME MEASURES

The main outcome measures were survival and bacteriologic response, defined by consecutive negative blood cultures for MAC at least 2 weeks apart within 16 weeks of study entry.

RESULTS

Prior AIDS diagnosis, low Karnofsky score, active unstable AIDS-related conditions, absence of antiretroviral therapy and absence of Pneumocystis carinii pneumonia prophylaxis were associated with shorter survival by univariate regression using the proportional hazards model. On multivariate analysis, antiretroviral therapy was not an independent predictor of mortality, and previous rifabutin prophylaxis was independently associated with poor survival outcomes, a result consistent across study treatment. Using a logistic regression model, baseline quantitative mycobacterial load [relative odds of clearing, 1.97 for a decrease of 1 log10 colony forming count; 95% confidence interval (CI), 1.36-2.87; P < 0.001] and Karnofsky score were the only statistically significant univariate predictors of clearance, although previous prophylaxis with rifabutin was also a significant predictor in a multivariate model (relative odds of clearing, 0.39; 95% CI, 0.17-0.88; P < 0.05).

CONCLUSIONS

This study indicates that although the level of MAC bacteremia is an important predictor of clearance, it is not associated with survival.

A new X-ray based osteoporosis screening tool provides accurate and precise assessment of phalanx bone mineral content

Many devices currently available for the assessment of osteoporosis require a significant capital investment, are not portable, and require specially trained operators. The objective of this study was to assess the accuracy and precision of a new tabletop dual-energy computed digital absorptiometry (CDA) device (accuDEXA, Schick Technologies, Long Island City, NY) designed to automatically and instantaneously assess bone mineral content (BMC) and bone mineral density (BMD) of the middle finger. BMC and BMD of 26 cadaveric forearms were measured by dual-energy X-ray absorptiometry, radiographic absorptiometry (RA), and CDA. accuDEXA measurements were repeated five times with and without repositioning on 10 forearms. The portion of the finger evaluated by accuDEXA was then excised, measurements of the specimen were again obtained using the accuDEXA device, and the specimen was incinerated to determine ash weight. BMC assessed by accuDEXA and by RA were strongly correlated with ash weight of the excised phalanx specimens (r2 = 0.94 and r2 = 0.96, respectively). Short-term precision for BMD assessed by the accuDEXA device was 0.9% without repositioning, and 1.8% with repositioning. BMD determined by the accuDEXA device was strongly correlated with BMD of the hand and forearm (r2 = 0.56-0.69). Dual-energy CDA is a new bone densitometry technique that provides rapid, precise, and accurate measurements of the middle phalanx of the third finger. The technique may be useful for widespread testing of osteoporotic patients.

A randomized trial of N-acetylcysteine for prevention of trimethoprim-sulfamethoxazole hypersensitivity reactions in Pneumocystis carinii pneumonia prophylaxis (CTN 057). Canadian HIV Trials Network 057 Study Group

Hydroxylamine derivatives of sulfamethoxazole may be the reactive metabolites that cause adverse reactions to trimethoprim-sulfamethoxazole (TMP-SMX). The increased frequency of reactions observed in HIV-positive individuals is hypothesized to be due to systemic glutathione deficiency and a decreased ability to scavenge these metabolites. Two hundred and thirty-eight patients were randomized to receive or not receive N-acetylcysteine (3 g of the 20% liquid solution) 1 hour before each dose of TMP-SMX (trimethoprim 80 mg, sulfamethoxazole 400 mg) twice daily, which was initiated as primary Pneumocystis carinii pneumonia prophylaxis. Forty-five patients had to discontinue TMP-SMX within 2 months because of fever, rash, or pruritus including 25 of 102 patients (25%) who were receiving TMP-SMX alone and 20 of 96 patients (21%) who were randomized to TMP-SMX and N-acetylcysteine. The difference between treatment groups is 4% (95% confidence interval [CI]: -16%, +9%). No independent association was found with the hypersensitivity reaction and age, gender, race, HIV risk factor, prior AIDS, concurrent use of fluconazole, or baseline CD4. N-acetylcysteine at a dose of 3 g twice daily could not be shown to prevent TMP-SMX hypersensitivity reactions in patients with HIV infection.

Does in vitro susceptibility to rifabutin and ethambutol predict the response to treatment of Mycobacterium avium complex bacteremia with rifabutin, ethambutol, and clarithromycin? Canadian HIV Trials Network Protocol 010 Study Group

The in vitro susceptibilities of baseline Mycobacterium avium complex (MAC) blood isolates from 86 patients with AIDS who were treated with clarithromycin, ethambutol, and rifabutin were determined to examine whether these results predict bacteriologic response to treatment. No patient received prior prophylaxis with clarithromycin or azithromycin. Minimum inhibitory concentrations (MICs) of clarithromycin for all isolates were < or = 2 micrograms/mL. The median MIC of rifabutin was between 0.25 and 0.5 microgram/mL, and all isolates were susceptible to < or = 2 micrograms of rifabutin/mL. The median MIC of ethambutol was 4 micrograms/mL, and the MIC90 was 8 micrograms/mL. There was no correlation between ethambutol susceptibility and subsequent bacteriologic clearance. At all time points through week 12, bacteriologic clearance occurred more frequently in patients with isolates for which MICs of rifabutin were lower, but this difference was statistically significant only at week 2. Susceptibility testing for baseline MAC isolates from AIDS patients not previously treated with clarithromycin or azithromycin does not appear to be useful in guiding therapy.

Serum immunoreactive erythropoietin levels and associated factors amongst HIV-infected children

OBJECTIVES

To determine the spectrum of serum immunoreactive erythropoietin (SIE) levels amongst HIV-infected children aged < 13 years in relation to the levels among healthy children as well as those with renal failure; to examine the relationship between clinical and laboratory parameters and SIE levels.

DESIGN

A cross-sectional study with a descriptive non-interventional format. HIV-infected Canadian subjects were recruited through four tertiary Canadian and one Bahamian centre. Children with renal failure and healthy children were recruited from one of the Canadian centres.

METHODS

Study subjects had clinical and laboratory profiles determined at baseline and at each of five follow-up periods over 1 year. SIE levels were measured by radioimmunoassay with a normal range of 12-28 IU/I. Data handling and statistical functions were performed by the Canadian HIV Trials Network.

RESULTS

The study enrolled 133 HIV-infected subjects and 38 controls. Of these, 117 HIV-infected subjects, 24 healthy controls, and 11 controls with renal failure were eligible for analysis. The median age of infected subjects was 44 months, whereas that of healthy controls was 56 months, and 95 months for controls with renal failure. The median SIE levels were 14 and 11 IU/I for subjects with renal failure and healthy subjects, respectively. The median SIE level was 61 IU/I among zidovudine (ZDV)-treated subjects and 22 IU/I among ZDV-naive HIV-infected subjects. HIV-infected children almost invariably had SIE levels < 200 IU/I. The median SIE levels amongst HIV-infected subjects whose hemoglobin levels were < 100 g/l were 98 and 31 IU/I for ZDV-treated and ZDV-naive subjects, respectively (P = 0.002). This difference in median SIE levels between ZDV-treated subjects and ZDV-naive subjects was also observed among subjects whose hemoglobin levels were > 100 g/l (median, 58 and 15 IU/l, respectively; P < 0.001). Hemoglobin level was the most important predictor of log10 SIE (P < 0.01 for ZDV-treated and ZDV-naive subjects).

CONCLUSIONS

SIE levels amongst HIV-infected children were affected by HIV infection, use of ZDV, and presence or absence of anemia. SIE levels amongst HIV-infected children were generally lower than 200 IU/I. This characterization of SIE levels will facilitate clinical trials of exogenous recombinant human erythropoietin in HIV-infected children with anemia.

Clindamycin with primaquine vs. Trimethoprim-sulfamethoxazole therapy for mild and moderately severe Pneumocystis carinii pneumonia in patients with AIDS: a multicenter, double-blind, randomized trial (CTN 004). CTN-PCP Study Group

This double-blind, randomized, multicenter trial compared clindamycin/primaquine (Cm/Prq) with trimethoprim-sulfamethoxazole (TMP-SMZ) as therapy for AIDS-related Pneumocystis carinii pneumonia (PCP). Forty-five patients received clindamycin (450 mg four times daily [q.i.d.]) and primaquine (15 mg of base/d); 42 received TMP-SMZ (320 mg/1,600 mg q.i.d. if weight of > or = 60 kg or 240 mg/1,200 mg q.i.d. if weight of < 60 kg) plus placebo primaquine. Overall, the efficacy of Cm/Prq was similar to that of TMP-SMZ (success rate, 76% vs. 79%, respectively); Cm/Prq was associated with fewer adverse events (P = .04), less steroid use (P = .18), and more rashes (P = .07). These differences were even greater for patients with PaO2 of > 70 mm Hg (P = .02, P = .04, and P = .02, respectively). For patients with PaO2 of < or = 70 mm Hg (23 Cm/Prq recipients and 21 TMP-SMZ recipients), the efficacy of Cm/Prq was similar to that of TMP-SMZ (success rate, 74% vs. 76%, respectively); Cm/Prq was associated with similar adverse events (P = .57), steroid use (P = .74), and rashes (P = .78). This trial confirms that Cm/Prq is a reasonable alternative therapy for mild and moderately severe PCP.

Estimating the effect of treatment on quality of life in the presence of missing data due to drop-out and death

Quality of life was measured in a study of two multidrug regimens for mycobacterium avium complex MAC bactaeremia using the MOS-HIV questionnaire. The effect of treatment on quality of life was estimated at each follow-up time in three ways: (1) using only the observed data, (2) after assigning the worst possible quality of life scores for individuals who died, and (3) after imputing missing scores for patients who either died or dropped out of the study. The overall quality of life scores were also compared between treatment groups with categorical generalized estimating equation models and three-dimensional graphs. Of the 179 patients included in these analyses, 84 (47%) either died or dropped out during the 16 week study period. When the quality of life scores were compared between the treatment groups with the Wilcoxon rank sum test using only the observed data, there was no significant difference between the groups at 16 weeks of follow-up. When the worst possible quality of life scores were assumed for patients who had died, both the magnitude and the statistical significance of the difference in the quality of life scores between the groups increased. Imputing missing data for patients who either dropped out or died resulted in even larger differences in quality of life between the treatment groups. We conclude that ignoring missing data due to drop-outs and death can result in an underestimation of the treatment effect and overly optimistic statements about the outcome of the participants on both treatment arms due to the selective drop-out of participants with poorer quality of life. To obtain a valid assessment of the effect of treatment on quality of life, the experience of the patients who died or dropped out of the study must be considered.

Validation of the modified multisystem organ failure score as a predictor of mortality in patients with AIDS-related Pneumocystis carinii pneumonia and respiratory failure

STUDY OBJECTIVES

To validate a previously developed multisystem organ failure (MSOF) score with and without the addition of the lactate dehydrogenase (LDH) level as a predictor of survival to hospital discharge in patients with AIDS-related Pneumocystis carinii pneumonia (PCP) and acute respiratory failure (ARF).

DESIGN

Retrospective chart review between April 1, 1991, and September 30, 1996.

SETTING

University-affiliated tertiary care center in downtown Vancouver, British Columbia, Canada.

PATIENTS

All patients with PCP-related ARF admitted to the ICU of St. Paul's Hospital during the study period.

INTERVENTIONS

As putative prognostic instruments, data were extracted regarding the APACHE II (acute physiology and chronic health evaluation II), acute lung injury (ALI), AIDS, and modified MSOF scores, as well as LDH levels, at entry to the ICU. Patients were stratified based on an LDH level of < or > or = 2,000 U/L and this threshold was assessed in its predictability of outcome when added to each of the above scores. For APACHE II, the score was categorized in six groups and evaluated with and without inclusion of the LDH. Receiver operating characteristic curves were constructed for LDH and for each score with and without the LDH level to assess accuracy of prediction. The area under each curve was calculated and compared to estimate the statistical significance of observed differences.

MEASUREMENTS AND RESULTS

There were 40 admissions to the ICU of 38 patients with 52.5% mortality. The ALI and AIDS scores were not predictive of outcome. The modified MSOF and APACHE II scores were significant predictors of survival and the performance of both was enhanced by the addition of LDH.

CONCLUSIONS

Both the APACHE II and the modified MSOF scores were significant predictors of outcome in the patient population studied. These results validate the modified MSOF score as an effective predictor of survival to hospital discharge among patients with AIDS-related PCP who develop ARF and the performance of the score is enhanced by the addition of the LDH level.

Economic analysis of fluconazole versus amphotericin B for the treatment of candidemia in non-neutropenic patients

Fluconazole (FLU) is an alternative to amphotericin B (AMB) for the treatment of candidemia in non-neutropenic patients. This agent has similar clinical efficacy but significantly reduced adverse effects compared with AMB. Using the database from a Canadian randomised multicentre comparative trial of FLU versus AMB in the treatment of non-neutropenic patients with candidemia, an economic analysis of antifungal therapy was conducted from a Canadian hospital perspective. Patient records were examined for information containing hospital resource consumption. This included the costs for primary intravenous therapy with either AMB or FLU, laboratory tests, patient clinical monitoring and adverse effects management. The robustness of the baseline results were then tested by a comprehensive sensitivity analysis. The mean duration of therapy in the AMB and FLU arms was 17.1 and 23.7 days, respectively (p < 0.001). Assuming that all of the FLU was administered intravenously, the outcomes of the baseline economic analysis revealed that the treatment cost for patients randomized to receive FLU was approximately 50% higher than that for patients treated with AMB [AMB: $Can2370 vs FLU: $Can3578; p = 0.001 ($Can = Canadian dollars)]. In the sensitivity analysis, substitution to oral FLU after 7 days of intravenous therapy produced economic differences that were no longer statistically significant (AMB: $Can2370 vs FLU: $Can2705; p = 0.10). These results suggest that the FLU administration regimen used in the Canadian randomized trial for the treatment of candidemia in non-neutropenic patients may result in increased hospital costs compared with AMB. However, comparable expenditures could be realized if FLU is administered intravenously for the first 7 days and then orally in patients whose condition allows for reliable oral therapy.

Prospective randomized trial of two dose levels of interferon alfa with zidovudine for the treatment of Kaposi's sarcoma associated with human immunodeficiency virus infection: a Canadian HIV Clinical Trials Network study

PURPOSE

Interferon alfa alone has shown antitumor activity against Kaposi's sarcoma (KS), and phase I and II clinical trials showed that interferon and zidovudine could be administered safely to patients with human immunodeficiency virus (HIV)-associated KS. These observations led to our trial of zidovudine with two dose levels of interferon alfa.

METHODS

HIV-positive patients with KS were eligible if they were older than 18 years of age, had a performance status of 0 to 2, and were free of active infection. All patients received zidovudine 500 mg daily and were randomized to receive-interferon alfa 1 million U or 8 million U subcutaneously daily.

RESULTS

The 108 eligible and assessable patients were well balanced for known prognostic factors. Response was reported in 31% of high-dose therapy and 8% of low-dose therapy patients (P=.011). Response at both dose levels was higher for patients with CD4 counts greater than 150 x 10(9)/L. The median time to progression was longer for patients in the 8-million U arm (18 v 13 weeks; P=.002). Both hematologic and nonhematologic toxicities were higher in the high-dose arm; 50 of 54 patients who received 8 million U required dose alterations in the first 4 months compared with only 19 of 53 patients who received 1 million U (P=.0002). No significant differences were reported with respect to improvement in CD4 count, elimination of p24 antigen, or development of opportunistic infections.

CONCLUSION

Zidovudine and moderate-dose-interferon alfa may be combined safely for the treatment of HIV-associated KS, and both response to treatment and toxicity are dose related.

Determinants of rifabutin-associated uveitis in patients treated with rifabutin, clarithromycin, and ethambutol for Mycobacterium avium complex bacteremia: a multivariate analysis. Canadian HIV Trials Network Protocol 010 Study Group

Uveitis occurred in a substantial proportion of AIDS patients receiving rifabutin, 600 mg daily, together with clarithromycin and ethambutol for treatment of Mycobacterium avium complex bacteremia. A case-control study was undertaken to examine potential risk factors for developing uveitis. Of eight parameters examined, only baseline body weight predicted the development of uveitis by both univariate and multivariate analyses (P = .001). The incidence of uveitis was 14% in patients weighing >65 kg, 45% in patients between 55 and 65 kg, and 64% in patients <55 kg. Concomitant therapy with fluconazole, a drug known to raise serum rifabutin concentrations, was not associated with an increased incidence of uveitis. The risk of uveitis was markedly reduced when rifabutin was given at 300 mg daily in combination with clarithromycin and ethambutol.

Estimating sample size for continuous outcomes, comparing more than two parallel groups with unequal sizes

This paper contains a short generalization of a known method for sample size determination in the case of more than two parallel groups. The term 'set of allocation ratios' corresponding to the allocation ratio from the two-group design is defined. A formula using these ratios to determine the non-centrality parameter of the F distribution is deduced. It is shown that in case of more than two groups, equal group numbers does not constitute an optimal design. Two worked examples are presented.

Adherence to clinical guidelines for the therapeutic management of HIV disease

OBJECTIVE

To determine the knowledge of HIV-disease management and the adherence to contemporary guidelines among British Columbia physicians whose practices focused on HIV/AIDS.

DESIGN

Self-administered mail survey.

PARTICIPANTS

All 659 physicians registered in a province-wide HIV/AIDS drug treatment program.

OUTCOME MEASURES

Data on demographic and personal characteristics of respondents, level of HIV-related experience, use of preventive vaccinations and tests, and preferred approaches to the prophylaxis and treatment of common opportunistic infections. Knowledge scores in 4 areas of patient care, as well as an overall score, were computed by comparing respondents' answers with the therapeutic strategies recommended at the time of the survey. Associations between physician characteristics and knowledge scores were identified by linear regression analysis.

RESULTS

Of the 659 physicians surveyed, 65% returned responses: only 38% returned completed surveys while a further 27% returned a follow-up survey that asked nonrespondents about their demographic characteristics and HIV-related experience. Scores for specific areas of patient management ranged from 29% for the treatment of opportunistic infections to 62% for preventive measures, with a mean overall score of 47%. Physician knowledge in all areas of patient care was associated with the number of HIV-positive patients in the practice (p = 0.003 to p < 0.001). Physicians who were younger were more knowledgeable regarding preventive measures (p = 0.001); those whose practice location was in Vancouver had a greater knowledge of prophylaxis (p = 0.047); and those who had medical specialty training were more knowledgeable about the treatment of opportunistic infections (p = 0.009).

CONCLUSIONS

There is substantial disparity in how physicians approach the management of HIV and related conditions. Deviations from therapeutic guidelines are common and may be associated with physician characteristics, particularly lack of experience in managing HIV.

Physician concurrence with primary care guidelines for persons with HIV disease

An anonymous questionnaire was mailed to 3 groups of physicians in British Columbia: 659 registrants of a province-wide human immunodeficiency virus (HIV) drug treatment programme (Group 1); 765 who had had a patient test positive for HIV (Group 2); and a random sample of 484 (Group 3). Questionnaires provided data about: physician's demographic and personal characteristics; HIV-related patient care experience; and 12 knowledge-based items. Responses were received from 65% of Group 1, 68% of Group 2 and 70% of Group 3, with complete information received from 38% of Group 1 and 50% of Groups 2 and 3. Summary knowledge scores were computed by comparing physician responses to recommendations of contemporary guidelines. Regression techniques identified associations between physician characteristics and knowledge scores. Multivariate analysis revealed an inverse relationship between knowledge and physician age in all groups (all P < 0.01). Increased knowledge was associated with the number of currently active HIV-positive patients in Groups 1 and 2 (all P < 0.001), and lack of specialization in Groups 2 and 3 (both P < 0.001).

Stratification of prostate-specific antigen level and results of transrectal ultrasonography and digital rectal examination as predictors of positive prostate biopsy

OBJECTIVE

To determine which of several variables--age, serum level of prostate-specific antigen (PSA), findings of transrectal ultrasonography (TRUS) and findings of digital rectal examination (DRE)--are the best predictors of positive prostate biopsy results.

SETTING

An urban, university-affiliated tertiary care hospital.

PATIENTS

a cohort of 1330 consecutive men referred to the diagnostic imaging department for TRUS and TRUS-guided prostate biopsy. Each patient was referred after examination by a urologist because of clinical suspicion of prostate cancer.

METHODS

All of the men had undergone prior determination of serum level of PSA. Repeat DRE was performed at the time of imaging. The variables age, PSA level, TRUS findings and DRE findings were tested aline and in combination as predictors of positive biopsy results by means of logistic regression analysis. A summary of percentage risk for positive biopsy results was constructed for each combination of statistically significant variables, stratified for age.

RESULTS

Cancer was detected in 541 men (40.7%). A strong correlation was observed between serum PSA level and the likelihood of positive biopsy result (p < 0.001). Of 402 men with normal age-specific PSA, 109 (27.1%) had positive biopsy results. Of 403 men with PSA of 10 ng/mL or more, 233 (57.8%) had cancer. The level of serum PSA was also related to the number of prostate sextants harbouring cancer (p < 0.001). TRUS findings at the time of biopsy were a strong predictor of cancer of the PSA level was abnormal (p < 0.001). DRE results alone did not correlate with positive biopsy results, regardless of age, PSA level of TRUS findings.

CONCLUSIONS

Men in whom there is a clinical concern for prostate cancer should undergo prostate biopsy if there is any elevation of age-specific PSA, particularly if the findings of TRUS are also abnormal. Because DRE alone was not predictive of biopsy outcome, algorithms for prostate cancer detection that rely on abnormal DRE results to identify men who should undergo biopsy will miss a significant number of cancers.