The prognostic role of histomorphological subtyping in nonmetastatic papillary renal cell carcinoma after curative surgery: is subtype really irrelevant? A propensity score matching analysis of a multi-institutional real life data

BACKGROUND AND AIM

The role of histomorphological subtyping is an issue of debate in papillary renal cell carcinoma (papRCC). This multi-institutional study investigated the prognostic role of histomorphological subtyping in patients undergoing curative surgery for nonmetastatic papRCC.

PATIENTS AND METHODS

A total of 1,086 patients undergoing curative surgery were included from a retrospectively collected multi-institutional nonmetastatic papRCC database. The patients were divided into 2 groups based on histomorphological subtyping (type 1, n = 669 and type 2, n = 417). Furthermore, a propensity score-matching (PSM) cohort in 1:1 ratio (n = 317 for each subtype) was created to reduce the effect of potential confounding variables. The primary outcome of the study, the predictive role of histomorphological subtyping on the prognosis (recurrence free survival [RFS], cancer specific survival [CSS] and overall survival [OS]) in nonmetastatic papRCC after curative surgery, was investigated in both overall and PSM cohorts.

RESULTS

In overall cohort, type 2 group were older (66 vs. 63 years, P = 0.015) and more frequently underwent radical nephrectomy (37.4% vs. 25.6%, P < 0.001) and lymphadenectomy (22.3% vs. 15.1%, P = 0.003). Tumor size (4.5 vs. 3.8 cm, P < 0.001) was greater, and nuclear grade (P < 0.001), pT stage (P < 0.001), pN stage (P < 0.001), VENUSS score (P < 0.001) and VENUSS high risk (P < 0.001) were significantly higher in type 2 group. 5-year RFS (89.6% vs. 74.2%, P < 0.001), CSS (93.9% vs. 84.2%, P < 0.001) and OS (88.5% vs. 78.5%, P < 0.001) were significantly lower in type 2 group. On multivariable analyses, type 2 was a significant predictor for RFS (HR:1.86 [95%CI:1.33-2.61], P < 0.001) and CSS (HR:1.91 [95%CI:1.20-3.04], P = 0.006), but not for OS (HR:1.27 [95%CI:0.92-1.76], P = 0.150). In PSM cohort balanced with age, gender, symptoms at diagnosis, pT and pN stages, tumor grade, surgical margin status, sarcomatoid features, rhabdoid features, and presence of necrosis, type 2 increased recurrence risk (HR:1.75 [95%CI: 1.16-2.65]; P = 0.008), but not cancer specific mortality (HR: 1.57 [95%CI: 0.91-2.68]; P = 0.102) and overall mortality (HR: 1.01 [95%CI: 0.68-1.48]; P = 0.981) CONCLUSIONS: This multiinstitutional study suggested that type 2 was associated with adverse histopathologic outcomes, and predictor of RFS and CSS after surgical treatment of nonmetastatic papRCC, in overall cohort. In propensity score-matching cohort, type 2 remained the predictor of RFS. Eventhough 5th WHO classification for renal tumors eliminated histomorphological subtyping, these findings suggest that subtyping is relevant from the point of prognostic view.

Assessing the Performance of Chat Generative Pretrained Transformer (ChatGPT) in Answering Andrology-Related Questions

OBJECTIVE

The internet and social media have become primary sources of health information, with men frequently turning to these platforms before seeking professional help. Chat generative pretrained transformer (ChatGPT), an artificial intelligence model developed by OpenAI, has gained popularity as a natural language processing program. The present study evaluated the accuracy and reproducibility of ChatGPT's responses to andrology-related questions.

METHODS

The study analyzed frequently asked andrology questions from health forums, hospital websites, and social media platforms like YouTube and Instagram. Questions were categorized into topics like male hypogonadism, erectile dysfunction, etc. The European Association of Urology (EAU) guideline recommendations were also included. These questions were input into ChatGPT, and responses were evaluated by 3 experienced urologists who scored them on a scale of 1 to 4.

RESULTS

Out of 136 evaluated questions, 108 met the criteria. Of these, 87.9% received correct and adequate answers, 9.3% were correct but insufficient, and 3 responses contained both correct and incorrect information. No question was answered completely wrong. The highest correct answer rates were for disorders of ejaculation, penile curvature, and male hypogonadism. The EAU guideline-based questions achieved a correctness rate of 86.3%. The reproducibility of the answers was over 90%.

CONCLUSION

The study found that ChatGPT provided accurate and reliable answers to over 80% of andrology-related questions. While limitations exist, such as potential outdated data and inability to understand emotional aspects, ChatGPT's potential in the health-care sector is promising. Collaborating with health-care professionals during artificial intelligence model development could enhance its reliability.

Technical note: Energy dependence of the Gafchromic EBT4 film: Dose-response curves for 70 kV, 6 MV, 6 MV FFF, 10 MV FFF, and 15 MV x-ray beams

BACKGROUND

EBT4 was newly released for radiotherapy quality assurance to improve the signal-to-noise ratio in radiochromic film dosimetry. It is important to know its dose-response characteristics before its use in the clinic.

PURPOSE

This study aims to investigate and compare the dose-response curves of the Gafchromic EBT4 film for megavoltage and kilovoltage x-ray beams with different dose levels, scanning spatial resolutions, and sizes of region of interest (ROI).

METHODS

EBT4 film (Lot#07052201) calibration strips (3.5 × 20 cm2 ) were exposed to a 10×10 cm2 open field at doses of 0, 63, 125, 500, 750, 1000 cGy using 6 MV photon beam. EBT4 film strips from the same lot were then exposed to each x-ray beam (6 MV, 6 MV FFF, 10 MV FFF, 15 MV, and 70 kV) at six dose values (50, 100, 300, 600, 800, 1000 cGy). A full sheet (25 × 20 cm2 ) of EBT4 film was irradiated at each energy with 300 cGy for profile comparison with the treatment planning calculation. At two different spatial resolutions of 72 and 300 dpi, each film piece was scanned three consecutive times in the center of an Epson 10000XL flatbed scanner in 48-bit color. The scanned images were analyzed using FilmQA Pro. For each scanned image, an ROI of 2 × 2 cm2 at the field center was selected to obtain the average pixel value with its standard deviation in the ROI. An additional ROI of 1 cm diameter circle was also used to evaluate the impact of ROI shape and size, especially for FFF beams. The dose value, average dose-response value, and associated uncertainty were determined for each energy and relative responses were analyzed. The Student's t-test was performed to evaluate the statistical significance of the dose-response values with different color channels, ROI shapes, and spatial resolutions.

RESULTS

The dose-response curves for the five x-ray energies were compared in three color channels. Weak energy dependence was found among the megavoltage beams. No significant differences (average ∼1.1%) were observed for all doses in this study among 6 MV, 6 MV FFF, 10 MV FFF, and 15 MV beams, regardless of spatial resolution and color channel. However, a statistically significant difference in dose-response was observed up to 12% between 70 kV and 6 MV beams.

CONCLUSIONS

The dose-response curves for Gafchromic EBT4 films were nearly independent of the energy of the photon beams among 6 MV, 6 MV FFF, 10 MV FFF, and 15 MV. For very low-energy photons (e.g., 70 kV), a separate calibration from the same low-energy x-ray is necessary.

Effects of Flooring Types on Growth Performance, Behaviour and Health of Dairy Calves

In this study, perforated rubber mats (PRM), concrete floor bedded with long wheat straw (CLS and concrete floor bedded with wheat straw (CS) were compared as flooring types for dairy calves. Growth, feed efficiency ratio, gains in body measurements, some behavioural activities as well as faecal scores, bedding scores and calf’s cleanliness scores of the dairy calves were evaluated for 6 months. Overall growth rate differed significantly due to types of floor, and total weight gains of the dairy calves in PRM group was 7.0% and 16.0% higher than those of calves in CLS and CS groups respectively. However, differences with regard to the amount of dry matter of milk, concentrate as well as total dry matter of the feeds consumed per kg of weight gain during pre-weaning and post-weaning periods among the PRM, CS and CLS groups were not statistically significant. When, gains in linear body measurements were evaluated, total gains in height at withers, body length, chest depth and heart girth of the calves in PRM group were superior to those in CLS and CS groups. The calves in PRM group had high growth rate along with high percentage of time spent for lying behaviour which is one the most significant activities among the behaviours of the calves. The calves kept on PRM group exhibited 52.6% and 45.5% higher percentage of time spent for lying behaviour than those in CS and CLS groups respectively. Data regarding the bedding scores and calf's cleanliness scores also revealed that the PRM flooring was the cleanest and driest one compared to the other flooring types, and the calves in the PRM group were cleaner than those in CLS and CS groups. Calves in PRM group exhibited significantly (P<0.01) lover faecal consistency scores than those in CLS and CS groups. In conclusion, based upon growth rate, feed efficiency ratio, behavioural parameters as well as the bedding scores, calf's cleanliness scores and faecal consistency scores, PRM is preferable to CLS and CS floorings for individual dairy calves' pens.

How accurate is 68Gallium-prostate specific membrane antigen positron emission tomography / computed tomography (68Ga-PSMA PET/CT) on primary lymph node staging before radical prostatectomy in intermediate and high risk prostate cancer? A study of patient- and lymph node- based analyses

BACKGROUND AND AIM

Gallium-68 (68Ga)-Prostate Membrane Specific Antigen Positron Emission Tomography/Computed Tomography (68Ga-PSMA PET/CT) is an emerging diagnostic modality which is gaining importance in individualized prostate cancer (PCa) management era. This study aimed to investigate the diagnostic accuracy of ⁶⁸Ga-PSMA PET/CT on primary LN staging before radical prostatectomy (RP) in intermediate and high risk PCa.

MATERIALS AND METHODS

The retrospectively documented 49 patients with intermediate and high risk non-metastatic PCa who had ⁶⁸Ga-PSMA PET/CT before RP were enrolled into this study. The histopathology of dissected LNs was used as reference standard to evaluate the accuracy of ⁶⁸Ga-PSMA PET/CT on primary LN staging, both in per-patient (n = 49) and in per-node (n = 454) analyses. The diagnostic accuracy was investigated using sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV), and by area under the curve (AUC) provided using receiver operating curve (ROC) analysis.

RESULTS

Median age was 64 (48-79) years and, median and mean PSA values were 10 (1.31-138) ng/ml and 16.2 (±19.8) ng/ml, respectively. 22 (44.9%) and 27 (55.1%) of patients had intermediate and high risk PCa, respectively. A total of 5 (10.2%) patients had histopathologically proven LN metastasis and 3 (60%) of them was detected in ⁶⁸Ga-PSMA PET/CT. In per patient analysis, the sensitivity, specifity, PPV and NPV of ⁶⁸Ga-PSMA PET/CT on primary LN staging were 0.60, 0.96, 0.60 and 0.96, respectively. Among overall 454 LNs, 16 (3.5 %) of them were reported as metastatic in histopathology and, 13 (2.9%) of these metastatic LNs were detected in ⁶⁸Ga-PSMA PET/CT. In per-node analysis, the sensitivity, specificity, PPV and NPV of ⁶⁸Ga-PSMA PET/CT on primary LN staging were 0.82, 0.99, 0.87 and 0.99, respectively. The ROC analyses found AUCs for primary LN staging as 0.777 (95%CI:0.508-1.0) in per patient analysis and, as 0.904 (95%CI:0.790 - 1.0) in per node analysis, respectively.

CONCLUSION

The use of ⁶⁸Ga-PSMA PET/CT has promising diagnostic accuracy on primary LN staging before RP in intermediate and high risk PCa. However, the efforts should be taken to increase sensitivity of ⁶⁸Ga-PSMA PET/CT in individualized treatment era.

Indication for Y Chromosome Microdeletion Analysis in Infertile Men: Is a New Sperm Concentration Threshold Needed?

OBJECTIVE

To describe the prevalence of Y-chromosome deletions in patients with a sperm concentration of less than 5 million/mL. To also determine a new sperm threshold for Y-chromosome analysis in men with infertility.

METHODS

A total of 3023 patients who had a semen concentration of less than 5 million/mL included in this retrospective study. All of these patients had a genetic evaluation, hormonal evaluation, and 2 abnormal semen analyses.

RESULTS

Y-chromosome deletions were present in 116 (3.8 %) patients with sperm concentration <5 million/mL. The frequency of a Y-chromosome deletions was 6.8%, 1.0%, 0.15% in azoospermic men, in men with sperm concentrations of 0-1 million /mL, in men with sperm concentrations of 1-5 million/mL. Patients were divided into 2 groups regarding the determined new sperm threshold. The sensitivity and specificity of the Y-chromosome deletions test were 92.2.7% and 49.3 %, 99.1%, and 22.1% in patients with azoospermia and sperm concentrations <1 million/mL, respectively. If the sperm concentration thresholds of azoospermia or <1 million/mL, are applied, the number of tests decreased to 50.5% (1442 tests) and 23.1% (643 tests), respectively. Approximately $108,150 and $48,225 would be saved if the sperm thresholds were azoospermia and <1 million/mL, respectively CONCLUSION: The current threshold of sperm concentration for Y-chromosome deletions is controversial. The new proposed sperm threshold for genetic testing of 1 million/mL would increase sensitivity and more cost-effective compared to the current threshold.

Evidence for conjugated linoleic acid-induced embryonic mortality that is independent of egg storage conditions and changes in egg relative fatty acids

Three experiments were performed to determine the effect of conjugated linoleic acid (CLA) on embryonic development in the absence of vitelline membrane disruption. In experiment 1, when eggs from control and CLA (0.5%)-fed hens were stored at 21 or 15 degrees C for 48 h, mineral movement between the yolk and albumen was not observed (with the exception of Mg and Na). Also, it was found that CLA-induced changes in yolk fatty acid content (e.g., increased saturated fatty acids and CLA) had begun to change after 5 d of feeding hens CLA, and no differences were detected in fatty acid composition after 14 d. In experiment 2, the hatchability of eggs incubated directly after oviposition or stored 24 h at 21 or 15 degrees C was determined from hens fed control or 0.5% CLA diets. Regardless of storage conditions, CLA reduced hatchability. These data showed that CLA elicits negative effects on hatchability independent of vitelline membrane disruption or egg storage condition. In experiment 3, eggs were collected from hens fed 0 or 1% CLA daily for 3 wk, stored at 21 degrees C for 24 h, and incubated. Not only did CLA decrease hatchability, the data showed as the days of CLA feeding increased, the days of survival during incubation decreased. Average days of embryonic survival during incubation for the CLA group diminished to 18.0, 13.4, and 6.3 d for wk 1, 2, and 3 of CLA feeding, respectively, and control remained at 20.6, 20.8, and 19.8 for the 3 wk. These studies suggested that without the disruption of the vitelline membrane, hatchability and embryonic days of survival were significantly reduced by maternal CLA feeding in comparison to control-fed hens. Evidence that embryos die earlier the longer the hens are fed CLA, even though no additional changes in the fatty acid content of eggs were found, suggested that factors other than storage and egg yolk fatty acid composition played a role in CLA-induced embryonic mortality.

Migration of an ingested needle to the mesentery, causing intestinal necrosis

A case of an intra-abdominal sharp foreign body with migration to the mesentery vessels, causing intestinal necrosis in a 20-year-old patient is presented. Emergency surgery with 75 cm small bowel resection was performed.

Changes in collagen and elastic fiber contents of the skin, rectus sheath, transversalis fascia and peritoneum in primary inguinal hernia patients

BACKGROUND

It has been claimed that inguinal hernia is not a local disease; it is a local manifestation of a systemic disorder of collagen metabolism. Previous studies have shown that patients with inguinal hernia have some anomalies in collagen metabolism and changed ratio of collagen types.

AIM

To search the changes in collagen and elastic fiber contents of the skin, rectus sheath, transversalis fascia and peritoneum in primary inguinal hernia patients.

METHODS AND MATERIALS

Twenty patients operated on for inguinal hernia (HR) included in the study (11 direct and 9 indirect). Nine patients underwent open cholecystectomy served as the control group (CC). A 0.5 x 1 cm. tissue was sampled from skin, rectus sheath, transversalis fascia and peritoneum in HR group. Skin, rectus sheath and peritoneum samples were taken from the patients in CC group. The sections of those samples were submitted to two different staining methods: "Masson's trichrome" for collagen and "van Gieson" for elastin fibers and graded with light microscopy.

RESULTS

The rectus sheath samples of CC had higher staining scores for both collagen and elastin fibers in comparison with HR (p = 0.032 and p = 0.026, respectively). CC had a significantly higher score for collagen in peritoneum samples (p = 0.019). There were no statistically significant differences between the patients with direct and indirect inguinal hernias for collagen or elastin fibers scores in skin, rectus sheath, transversalis fascia and peritoneum samples.

CONCLUSIONS

These findings, which concur with most of the previous studies, support the theory that inguinal hernia may not be merely a local disease and can be more generalized, at least a regional connective tissue disorder. Regarding the difference between direct and indirect hernias, it could not be possible to report a certain answer, and this issue should be considered together with previous quantitative researches and more sophisticated studies may take place in the future (Tab. 2, Fig. 2, Ref. 23).

Uncommon content in groin hernia sac

Groin hernia may have very unusual sac content. Vermiform appendix, acute appendicitis, ovary, fallopian tube and urinary bladder have been rarely reported. We aimed to present our experience with these unusual hernia contents. Records of 1,950 groin hernia patients were retrospectively analyzed. Vermiform appendix was found in 0.51% and acute appendicitis was found in 0.10% of groin hernia sacs. The incidence of appendix in femoral hernia was 5%, while inguinal hernia sac contained ovary and fallopian tube in 2.9% of the cases. The incidence of groin hernias containing urinary bladder was 0.36%. We also had 1 patient with incarcerated bladder diverticula in an indirect hernia sac. Iatrogenic bladder injury occurred in 2 patients. Although rare, a groin hernia sac may contain vermiform appendix and exceptionally acute appendicitis. Tubal and ovarian herniation in inguinal hernias can be found in adult and perimenopausal women with an incidence as high as in children. Urinary bladder hernia occurs with a similar incidence of tuba-ovarian hernia, however, it requires special attention because of a high risk of iatrogenic bladder injury during the inguinal dissection. Every effort should be made to preserve the organ found in hernia sac for an uneventful postoperative period.

The effect of dietary conjugated linoleic acid on egg yolk fatty acids and hatchability in Japanese quail

Conjugated linoleic acid (CLA) increased the ratio of saturated fatty acids to monounsaturated fatty acids in yolk and caused embryo mortality. Our preliminary studies showed that CLA had less of an effect on hatchability of quail than chickens. Hence, the objective was to determine the effects of dietary CLA on quail egg fatty acid content and hatchability. Eight male-female Japanese quail pairs per group were randomly assigned to diets containing 0 (canola oil; CO), 0.25, 0.5, 1, 2, or 3% CLA for 8 wk. Eggs were collected, held at 15 degrees C for 24 h, and then incubated. Three eggs from each group were collected for fatty acid analysis on the 45th day. At the end of the 8 wk, all quail were euthanized. Liver samples from female quail were obtained for fatty acid analysis. Diet containing 3, 2, or 1% CLA caused 100% embryo mortality after 6, 10, or 12 d of feeding, whereas overall hatchabilities in groups 0, 0.25, and 0.5 were 84, 86, and 64%, respectively. As the dietary CLA increased, egg and hepatic CLA increased, C16:0 increased and C16:1(n-7) and C18:1(n-9) decreased, whereas C18:0 remained unchanged. Diets containing 1, 2, or 3% CLA decreased the C20:4(n-6) levels in yolk (significantly) and liver (inconsistently) lipids. Yolk CLA levels from 0, 0.25, 0.5, 1, 2, and 3% CLA were 0.31, 0.90, 1.48, 2.44, 5.88, and 11.2%, respectively. The ratios of C16:0/C16:1(n-7) in yolks from groups fed 0, 0.25, 0.5, 1, 2, or 3% CLA were 8.2, 16.3, 20.4, 24.6, 26.1, and 28.6, respectively. The ratios of C18:0/C18:1(n-9) in yolks from hens fed 0, 0.25, 0.5, 1, 2, or 3% CLA were 0.28, 0.40, 0.48, 0.49, 0.69, and 0.83, respectively. Quail fed 0.25% CLA had increased egg size, whereas quail fed 2 or 3% had reduced egg size compared with those fed CO. Liver sizes (%) in all of the groups were increased, except for the group fed 0.25% CLA. These data suggest that CLA may affect hatchability possibly by changing the fatty acid composition of the yolk.

Leiomyosarcoma of the small intestine found within an inguinal hernia sac: a case report

Inguinal hernias and intra-abdominal malignancy are both common phenomena and their co-existence cannot be rare. Colon carcinomas are reported to be the most common cause of both intrasaccular and saccular tumours (1) but the occurrence of small intestine carcinoma inside an inguinal hernia has not been reported. We describe the first case--a leiomyosarcoma of the ileum--which was also complicated by irreduction.

Olive oil prevents the adverse effects of dietary conjugated linoleic acid on chick hatchability and egg quality

Dietary conjugated linoleic acid (CLA) decreases yolk 18:1(n-9), induces chick embryonic mortality and alters egg quality. A study was conducted to determine whether olive oil would prevent these adverse effects of CLA. Hens (15 per treatment) were fed diets containing 0.5 g corn oil/100 g (CO), 0.5 g CLA/100 g (CLA), 0.5 g corn oil plus 10 g olive oil/100 g (CO + OO) or 0.5 g CLA plus 10 g olive oil/100 g (CLA + OO). After 74 d of feeding, hens were placed on CO for 10 d. Hens were artificially inseminated weekly. For hatchability studies, fertile eggs were collected daily, stored at 15 degrees C for 24 h and then incubated. After 6 d of feeding, embryonic mortality rates were 15, 100, 8 and 16% in the CO, CLA, CO + OO and CLA + OO groups, respectively. When CLA-fed hens were fed the CO diet, hatchability improved to that of the CO group within 7 d. For fatty acid analysis, three eggs were obtained at the 7 d of feeding. Relative CLA levels of yolk from CO-, CLA-, CO + OO- and CLA + OO-fed hens were 0.11 +/- 0.01, 1.91 +/- 0.16, 0.08 +/- 0.04 and 0.69 +/- 0.07 g/100 g fatty acids, respectively. The ratios of 16:0/16:1(n-7) and 18:0/18:1(n-9) of yolk from CLA-fed hens were approximately 1- and approximately 1.5-fold greater, respectively, compared with those fed CO. OO prevented CLA-induced increases in 16:0 and 18:0 and the decrease in 18:1(n-9) in yolk. Fertile eggs were stored at 4 degrees C for 2 or 10 wk and analyzed for pH or mineral levels. Dietary CLA caused abnormal pH changes of albumen and yolk when eggs were stored at 4 degrees C. The pH of yolk and albumen from CO-fed hens after 10 wk of storage was 6.12 +/- 0.12 and 9.06 +/- 0.03, respectively, versus 7.89 +/- 0.25 and 8.32 +/- 0.16, respectively, in eggs from CLA-fed hens. OO prevented CLA-induced abnormal changes in the pH of albumen and yolks. Eggs from CLA-fed hens had greater iron, calcium and zinc concentrations and lower magnesium, sodium and chloride concentrations in albumen relative to those from hens fed CO. OO prevented CLA-induced mineral exchange between yolk and albumen, presumably by reducing the yolk saturated fatty acids, which are believed to disrupt the vitelline membrane during cold storage. This study suggests that the adverse effects of CLA may be due to the increased level of saturated fatty acids. However, because the addition of olive oil also lowered egg CLA content, the direct role of egg CLA on egg hatchability and quality cannot be ruled out.

Investigation of AGFA-8E56HD photographic emulsion and relief hologram structures by atomic force microscopy

Relief holograms are obtained on Agfa 8E56HD holographic emulsions by a Russian chemical-processing technique that is developed for their PE-2 holographic emulsion. We have shown that the three-dimensional surface profiles can easily be visualized by applying atomic force microscopy to measurement of the relief depth and relief spacing on holographic emulsions. The relief depth and thus diffraction efficiency decreases with increasing exposure time.

Air pollution profile of Bursa

Rapid urbanization and industrial development are the most important causes of air pollution in Bursa. Smoke and sulfur dioxide concentrations were measured at five stations over a period of 20 months between 1986 and 1987; the concentrations of the total suspended particles were determined in the samples collected at two stations in June and October 1986. Some of the trace elements (Fe, Pb, Cd, Zn) were measured in October 1988 by atomic absorption spectroscopy of 28 samples from two stations. The first-order regression equations were calculated in order to find the relationship between the concentrations of smoke, sulfur dioxide, and meteorological conditions. The trends in the concentrations of measured air pollutants were compared by the long- and short-term limit values, as specified in the regulation.

Regional differences in hip fracture risk in Turkey

The aims of this study were to compare the incidence of hip fracture in different regions of Turkey and to investigate causes for potential differences. Hip fracture cases from two cities (Istanbul and Ankara) and three rural regions (Samsun, Erzurum and Diyarbakir) were compared with non-fractured controls from the same area with similar age and of the same sex. The risk of hip fracture was higher among persons living in rural areas than among persons living in urban areas, RR = 3.2 (p < 0.001) and 2.3 (p = 0.009) in men and women, respectively. Adjustment for differences in age and BMI between cases and controls did not substantially change these findings, RRadj = 2.7 (p < 0.001) and 2.1 (p = 0.036), neither did adjustment for exercise or differences in gonadal status in women. Education was the only adjustment factor that seemed to reduce differences between urban and rural areas, RRadj = 2.0 (p = 0.109) and 1.2 (p = 0.816). No difference in the risk of hip fracture could be detected between persons who migrated from rural to urban areas and persons born in urban areas. When restricting the analyses of differences between rural and urban areas to low-energy fractures, no difference in risk could be detected. When adjusting for differences in age and body mass index (BMI) the relative risks were RRadj = 0.8 (p = 0.873) and 1.2 (p = 0.852). The conclusion of these results is that the observed higher total risk of hip fracture in the rural areas of Turkey primarily can be explained by a larger proportion of high-energy fractures in the rural areas, whereas the risk of low-energy fractures seems to be similar.