Medical researchers often desire to categorize patients into monotonic response groups based on the relationship between continuous variables. Isotonic regression fits consist of level sets of increasing value, for which the estimated response is constant. However, the number of level sets obtained is often large, preventing simple description. This article introduces two new nonparametric methods called reduced isotonic regression and reduced monotonic regression, the latter being a two-sided extension of the former for use when the direction of the trend is unknown. Using a backward elimination algorithm, the new procedures reduce the number of level sets by combining those whose values do not differ greatly. For the statistical relations examined here, the reduced monotonic method averaged at most 30% of the number of level sets obtained for isotonic regression. The method is illustrated with an example that examines the relationship between risk factors for survival among children with leukemia. In simulation studies, the reduced monotonic method fits the data as closely as alternative methods that combine isotonicity and smoothing, while improving greatly on isotonic regression. The method is also related to changepoint models of normally distributed sequences.
The objective of this study was to examine the clinical and pathological features of squamous cell carcinoma of the Tongue and Buccal Mucosa and understand their differences. This is a retrospective analysis of prospectively collected data of 735 patients with squamous cell carcinoma of the tongue and 665 cases of carcinoma of the buccal mucosa treated by surgery at our hospital. Statistical analysis was done to examine clinical and pathological differences between carcinoma of the tongue and the buccal mucosa with regards to age, gender, clinical T stage/N stage, pathological T stage/N stage, overall stage, grade, thickness, perinodal extension (PNE), lymphovascular emboli (LVE) and perineural invasion (PNI). Statistically significant differences were found for factors like age (p < 0.001), gender (p < 0.001), clinical T staging (p < 0.001) and pathological stage (p < 0.001), grade of tumor (p < 0.001) and perineural invasion (p < 0.001) between carcinoma of the tongue and the buccal mucosa. Forty-eight percent patients in either subsite had pathologically proven node negative necks (pN0, p = 0.88). Multivariate analysis for occult nodal metastases revealed that predictive factors were different for the two subsites. There are significant differences between cancers of the tongue and buccal mucosa for various clinical and pathological factors. This may be a reflection of the underlying differences in their causation and pathophysiology. Squamous cell carcinoma in these two subsites should therefore be regarded as clinico-pathologically distinct entities.
Two hundred twenty cases of unilateral chronic suppurative otitis media (CSOM) with dry central perforation were chosen for this study and myringoplasty were done. Age group ranged from 13 to 48 years. Four types of autogenous tissues were used as graft material. Grafting was done by underlay technique when temporalis fascia, tragal perichondrium, areolar tissue were used as graft material and when fat graft was used the ear lobule fat was placed directly into perforation through transcanal route. Postoperative follow-up was carried out up to 6 months. In this study, it was found that the younger age group has less impairment of hearing and better chance of tympanic membrane perforation closure than the older age group in CSOM with central perforation. Anterior perforations has less impairment of hearing and better result in successful closure of tympanic membrane than posterior perforation group. It was also observed that larger the size of perforation greater is the hearing impairment preoperatively and postoperative hearing gain is also less compared to small perforation. Best hearing improvement occurred using temporalis fascia. Failure occurred may be due to postoperative infection, respiratory tract infection, neglected post-operative advice etc.
There is variation in the primary site that causes metastasis to the jaw bones depending on age, sex and geographic distribution. Jaw bone metastases are rare and can be the first site of metastasis. We get approximately four cases in a year with metastatic disease manifesting in the jaw bones. Metastasis to jaw bone is associated with poor prognosis.
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