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The matched group analysis method in prospective studies is a variation of matched pairs analysis with the advantage of sampling error avoided in the choosing of pairs of subjects. An example is shown in which comparisons are given of mortality in triads of cases classified by the tar and nicotine level of the cigarettes they smoked and matched on 10 variables. The method can also be used in retrospective and autopsy studies.
We report the results of a nonrandomized, matched group survival study comparing 29 patients with a choroidal or ciliary body melanoma managed by enucleation alone to 29 patients managed by enucleation following external beam ocular irradiation (20 Gy in five fractions over 5-7 days just prior to enucleation). Variables on which the patients in the two groups were matched included age at time of enucleation, largest linear tumor dimension, location of the anterior tumor margin relative to the equator and ora serrata, melanoma cell type, and extrascleral tumor extension. The cumulative 5-year survival in the enucleation alone group was 57.9% (SE = 9.9%), whereas that in the preenucleation radiation therapy group was 63.9% (SE = 12.2%). This difference is not statistically significant (p greater than 0.5, Mantel-Haenszel test). The authors discuss the strengths and limitations of their study and the implications of their results.
Osteolysis and component loosening secondary to polyethylene (PE) debris are of paramount concern to today's joint replacement surgeon. This retrospective clinical study measures linear wear in 568 implanted total hip prostheses in which three different metals were used as bearing surfaces (307 stainless steel T-28 [Zimmer, Warsaw, IN], 162 cobalt chrome Tr-28 [Zimmer], and 99 nonion implanted titanium Miami Orthopedic Surgical Consultants [Biomet, Warsaw, IN] prostheses) implanted by a single surgeon over an 8-year period. The acetabular component in all cases was nonmetal-backed compression-molded PE, and all components were cemented. Linear wear was measured using the radiographic technique described by Livermore et al. (The effect of femoral head size on wear of the polyethylene acetabular component. J Bone Joint Surg 72A:518, 1990) in which change in acetabular component thickness is determined from serial radiographs. A separate evaluation of this technique confirmed accuracy to within 0.18 mm. Radiographs were also evaluated for femoral and acetabular radiolucencies, femoral subsidence, and osteolysis. Patients were matched for sex, age, weight, and length of follow-up period to eliminate these retrospective variables for comparison of wear. The patient-matched groups consisted of 77 patients from each group (43 women, 34 men) with the following demographics: age, 66 years; weight, 158.9 lbs.; follow-up period, 7.9 years. Results revealed linear wear rates of 0.06 stainless steel, 0.05 cobalt chrome, and 0.08 titanium in the patient-matched groups.(ABSTRACT TRUNCATED AT 250 WORDS)
The results of 73 total knee arthroplasties in 67 patients after a high tibial osteotomy (HTO) were carefully reviewed at an average follow-up period of 73 months (range, 24-132 months). An extensive clinical as well as radiographic review was performed in an attempt to evaluate parameters that might portend more favorable or worse outcomes. Additional comparisons were made with two groups of 73 primary TKAs matched according to age, gender, diagnosis, prosthetic fixation, and length of follow-up period. The two comparison groups differed in that one (Group A) was additionally matched to deformity before TKA with a second comparison group (B) matched to pre-HTO deformity. On the basis of a 100-point knee rating scale, 36% of the study group patients had either a fair or poor result or required additional surgery. This was significantly greater than either comparison group (p < 0.01). Factors that prognosticated a worse outcome in the HTO patients (p < 0.01) included (1) workmen's compensation patient, (2) history of reflex sympathetic dystrophy after HTO, (3) early onset (less than one year) or no period of relief of pain after HTO, (4) multiple surgeries before HTO, and (5) an occupation as a laborer.
We report the results of a nonrandomized, matched-group, survival and visual preservation study of patients with a choroidal or ciliary body melanoma managed by microsurgical resection of the tumor versus cobalt-60 episcleral plaque radiotherapy. Each treatment group consisted of 30 patients. All patients were matched on a case-by-case basis in terms of tumor size (largest linear tumor dimension), location of the anterior tumor margin relative to the ora serrata, location of the posterior tumor margin relative to the equator, and age at the time of treatment. Although the estimated actuarial 5-year survival probability was slightly greater in the resection group (85.2%) than in the cobalt plaque group (81.8%), this difference was neither clinically impressive nor statistically significant. In contrast, there was a substantially higher rate of early posttreatment severe visual loss in the resection group (P = .0008, Mantel-Haenszel test).
Visual evoked cortical potentials (VECPs) to midperipheral stimulation of the visual field were elicited in age-matched groups of patients with unilateral chronic simple glaucoma or ocular hypertension and normal subjects. With a multimodal stimulus approach comprising transient and steady-state pattern reversal and transient onset-offset VECPs, 82.1% of the glaucoma group and 50.9% of the ocular hypertensives revealed significant abnormalities (p less than 0.01) in one or more of the electrophysiological features measured, i.e., latency, phase, amplitude, and contrast threshold.
The treatment process with two prototypic neuroleptics--haloperidol and chlorpromazine--and the nontherapeutic effects of trihexyphenidyl on this process were studied in carefully matched groups of ten schizophrenics each, using a "double-blind", repeated-measure, longitudinal research design. Measurements of various aspects of psychopathology, social participation and clinical indices of arousal were made periodically and objective test of cognition and attention were given. The two treatment groups were highly comparable in epidemiological and clinical terms and differed significantly during the baseline period in only one of the 39 parameters. Longitudinal nonparametric analyses showed that significant therepeutic changes tended to occur more quickly and involved a wider spectrum of schizophrenic phenomena with haloperidol than with chlorpromazine. Parametric analyses also indicated that at the completion of the study, haloperidol-treated patients had significant improvement in many more dimensions than the chlorpromazine-treated patients and that the changes with haloperidol were generally of greater magnitude. At the same time, chlorpromazine treatment seemed to be more susceptible to the antagonistic effects of trihexyphenidyl. No differential patterns of responses were noted for the two neuroleptics to provide any clinical validity to the distinction often made between "sedative" and "activating" neuroleptics. These data were in agreement with those from a previous comparative study which had a very different research design and a somewhat different type of schizophrenic population. The clinical and potency differences between the two neuroleptics were again explained on the basis of the fact that chlorpromazine has much stronger built-in anticholinergic properties, which may be acting in opposition to the antipsychotic activity. It was suggested that the degree of inherent anticholinergic activity may be an important determinant of potency differences among presently known neuroleptics. The possible role of cholinergic mechanisms in schizophrenia was discussed.
PURPOSE: Currently no randomized studies show the relative morbidity and mortality of the open and endoluminal methods of abdominal aortic aneurysm (AAA) repair. The aim of this study was to analyze the outcome of two matched groups of patients with AAA, one undergoing open repair and the other undergoing endoluminal repair. METHODS: Two groups of patients who had undergone repair of AAA by open technique (group 1) or by endoluminal methods (group 2) were compared. A historic control cohort of 27 patients was selected from 56 consecutive patients who underwent open repair of AAA between January 1991 and February 1992. Patients considered unsuitable for the endoluminal method on the basis of computed tomography and aortography were excluded (n=29). Between May 1992 and November 1994 prospective data were recorded for 62 consecutive patients who underwent endoluminal repair by tube or bifurcated endografts. Twenty-eight patients who had been specifically referred for endoluminal AAA repairs because of preexisting severe medical comorbidities were excluded. Six of the endoluminal cases had failure, requiring conversion to open operation, and were excluded for separate analysis, leaving 28 patients in group 2. Patients in both groups were thus fit and suitable for either open or endoluminal repair and were comparable in relation to age, sex, risk factors, dimensions, and form of AAA. RESULTS: The mean values for operation time, blood loss, intensive care stay, and hospital stay for group 1 and group 2 were 2.6 versus 3.1 hours, 1422 versus 873 ml,* 1.8 versus 0.7 days,* and 12.4 versus 11.1 days, respectively (*p<0.05). Local/vascular complications occurred in 15% of patients in group 1 compared with 25% in group 2 (p=0.55), whereas remote/systemic complications occurred in 37% and 29%, respectively (p=0.3). Five of 28 patients in the endoluminal group had complications requiring early operative repair (n=3) or late revision (n=2). When comparison was made on an intention-to-treat basis (with failed procedures included), the incidence of local/vascular complications was significantly greater for endoluminal repair (p=0.047). CONCLUSIONS: The incidence of systemic/remote complications was similar for the two groups in spite of significantly less blood loss and shorter intensive care unit stay with endoluminal repair. The incidence of local/vascular complications had a tendency to be higher for endoluminal compared with standard open method (and was significantly greater if failed procedures were included). In this early experience with prototype devices, patients who were medically suitable for open surgical procedures did not derive benefit from the less invasive endoluminal technique with respect to duration of operation, length of hospital stay, or perioperative morbidity and mortality. On the other hand, because they also did not have worse outcome, a randomized study is now justified in this group.
This paper compares attention deficit disorder (ADD) with hyperactivity (ADDH) and without hyperactivity (ADDWO). The literature is outlined, revealing the areas of possible differences to be not only the core symptoms, but also associated conduct and emotional symptoms, social relations functioning, learning, medical disorders, family history, and course and outcome of the disorder. Empirical data are presented comparing age and sex matched groups of children from a speech/language clinic sample with ADDH (N = 40) and ADDWO (N = 40). Although the methods of the present study are different from those of previous studies, they nonetheless support a number of previous findings, and, further, give support to the external validity of the ADDWO diagnostic category.
A young (X = 36.8 years) and an old (X = 52.9 years) group (n = 12) matched for physical fitness performed a graded exercise test at the beginning and after a 4-month physical fitness program consisting of calisthenics, jogging, and recreational activities. The purpose of the study was to determine if there were any differences in response to physical training in the two age groups of similar fitness. Sixteen physiological and four biochemical variables were measured. There was no significant difference in VO2 max between the young and old groups. Also, there were no significant differences between groups for serum total lipids, cholesterol, triglycerides, or glucose levels. The effects of the training program were similar for both the young and old groups.
An investigation, using a prospective cohort study, was performed to estimate the prolongation of hospital stay caused by nosocomial infections in surgical patients. An evaluation of the one-to-one matching method, as a model for similar studies was also undertaken. Between 1992 and 1994, 225 of 1482 surgical patients (15%) developed infection. Of these, 223 evaluable patients were compared with 1256 uninfected cases, in an unmatched analysis. In a further analysis, 151 infected cases were matched one-to-one with uninfected controls, and other factors such as age, length of preoperative stay, presence of malignancy or diabetes and presence of foley catheters or drains, were evaluated. Patients with infection were hospitalized for 10.6 days longer than the matched controls. In the unmatched analysis, infected patients appear to remain in hospital for a further 17 days. The difference in the prolongation of stay between matched and unmatched groups indicates the importance of matching as an essential model for such studies. In cases where matching cannot be performed, the median can be a good alternative measure to the arithmetic mean.
35 out-patient Ss with demonstrable psychosomatic symptoms were matched with 35 psychiatric out-patients with "milder" forms of psychopathology, i.e., neurosis, personality disorders and latent schizophrenia. The psychosomatic group showed significantly more anatomy responses on the Rorschach but there was much overlap, leading to the conclusion that anatomy does not directly reflect simply psychosomatic disturbances but, rather, is associated with psychodynamics which tend to underlie psychosomatic illnesses.
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A retrospective descriptive study was designed to assess the quality of life (QoL) and psychosocial adjustment in long-term BMT survivors compared with a group of patients with haematological malignancies receiving maintenance chemotherapy (MC), matched for age, post-treatment time, sociodemographic and disease characteristics. The sample consisted of 91 long-term BMT survivors and 73 MC patients from three teaching hospitals in the UK. The results indicated that most of the BMT subjects had a good to excellent quality of life and, in some domains, even better adjustment than the MC patients. However, 20% of the BMT subjects had failed to return to full-time employment at a mean post-BMT time of almost 40 months. A significant number of BMT subjects were also identified with symptoms of anxiety and depression. The physical symptomatology had an association with psychological status. Impotence-related difficulties, decreased sexual satisfaction and altered body image were the main characteristics of psychosexual dysfunction in the BMT group. Poorer quality of life was predicted by the presence of depressive symptoms, low affirmation, and impoverished social adjustment.
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BACKGROUND: Allocation of cadaver kidneys by graded human leukocyte antigen (HLA) compatibility scoring arguably has had little effect on overall survival while prejudicing the transplant candidacy of African-American and other hard to match populations. Consequently, matching has been proposed of deduced amino acid residues of the individual HLA molecules shared by cross-reactive antigen groups (CREGs). We have examined the circumstances under which compatibility with either method impacted graft survival. METHODS: Using Cox proportional hazards regression modeling, we studied the relationship between levels of conventional HLA mismatch and other donor and recipient factors on primary cadaver kidney survival between 1981 and 1995 at the University of Pittsburgh (n=1,780) and in the United Network for Organ Sharing (UNOS) Scientific Registry during 1991-1995 (n=31,291). The results were compared with those obtained by the matching of amino acid residues that identified CREG-compatible cases with as many as four (but not five and six) HLA mismatches. RESULTS: With more than one HLA mismatch (> 85% of patients in both series), most of the survival advantage of a zero mismatch was lost. None of the HLA loci were "weak." In the UNOS (but not Pittsburgh) category of one-HLA mismatch (n=1334), a subgroup of CREG-matched recipients (35.3%) had better graft survival than the remaining 64.7%, who were CREG-mismatched. There was no advantage of a CREG match in the two- to four-HLA incompatibility tiers. Better graft survival with tacrolimus was observed in both the Pittsburgh and UNOS series. CONCLUSIONS: Obligatory national sharing of cadaver kidneys is justifiable only for zero-HLA-mismatched kidneys. The potential value of CREG matching observed in the one-HLA-mismatched recipients of the UNOS (but not the Pittsburgh) experience deserves further study.
To test the feasibility of comparing epilepsy treatment policies and outcome, a secondary and a tertiary epilepsy care facility have been audited in a previous study (1). Marked differences were observed in the treatment policies and outcome and in the distribution of seizure types and duration of epilepsy. For this reason the patients of that study were matched according to seizure type and duration of epilepsy, resulting in two groups each of 32 patients per centre. The outcome of treatment was assessed by using clinimetrical indexes for seizure frequency and severity and toxicity of medication, resulting in the Composite Index of Impairments (CII), reflecting all treatment-related impairments. For the statistical analysis the X2-test and the Kruskal-Wallis test were used. Differences were found to be statistically significant when p < 0.05. No distinct differences were found in the treatment policies of both centres. However, differences were observed in the outcome of treatment. The toxicity ratings in this study were significantly higher for the Epilepsy Centre. Also the Composite Index of Impairments (CII) was significantly higher at the Epilepsy Centre. The number of patients with a CII score of > 100 did not differ significantly for both centres. The finding that pharmacotherapy is similar in both centres, suggests that pharmacotherapy is pushed to its limits in both, and that referral to a tertiary facility is mainly for the non-pharmacotherapeutic care modalities available. For the corroboration of this assumption the use of a quality of life index would be more appropriate than the CII.
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