ObjectiveTo investigate the factors correlated with the visual outcome of idiopathic macular holes (IMH) after vitreoretinal surgery. MethodsA total of 57 eyes of 57 patients with IMH were included. There were 43 females (43 eyes) and 14 male (14 eyes), mean age was (60.46±4.79) years. All the eyes underwent best corrected visual acuity (BCVA), slit-lamp microscope, three-mirror contact-lens and optical coherence tomography (OCT) examinations. BCVA were examined with interactional visual chart and recorded with logarithm of the minimum angle of resolution (logMAR) acuity. The minimum diameter and base diameter of macular holes and central retinal thickness (CRT) were detected by OCT. The average logMAR BCVA of 57 eyes was 0.98±0.41. The minimum diameter and base diameter of macular holes were (479.53±164.16) μm and (909.14±278.65) μm. All the patients underwent pars plana vitrectomy combined with phacoemulsification cataract extraction and intraocular lens implantation. The mean follow-up period was (173.44±147.46) months. The relationships between final BCVA and these parameters were examined by single and multiple regression analysis. The valuable influence factors were filtrated and formulated using multiple linear regression models. ResultsAt the final follow-up, the logMAR BCVA of 57 eyes was 0.44±0.31, the CRT was (158.79±86.96) μm. The final BCVA was positive related to minimum diameter of macular holes and preoperative BCVA (r=0.420, 0.448; P=0.001, 0.000), negative related to postoperative CRT (r=-0.371, P=0.004). There was no relationship between the final BCVA and base diameter of macular holes, age and follow-up (r=0.203, -0.015, 0.000; P=0.130, 0.913, 0.999). The incidence of preoperative BCVA for postoperative BCVA was bigger than preoperative minimum diameter of macular holes (P=0.008, 0.020). ConclusionThe preoperative minimum diameter of macular holes and BCVA are related to postoperative BCVA in IMH eyes.
ObjectiveTo observe and analyze the risk factors related to vitreous re-hemorrhage (PVH) after anti-VEGF drugs combined with vitrectomy (PPV) in patients with proliferative diabetic retinopathy (PDR).MethodsRetrospective analysis study. From April 2017 to July 2018, 100 eyes of 87 PDR patients who were diagnosed in Jiaxing Eye Hospital and received anti-VEGF drugs combined with 25G PPV were included in the study. Among them, there were 44 eyes in 38 males and 56 eyes in 49 females. The age ranged from 26 to 83 years, with an average age of 57.72±8.82 years. All patients were type 2 diabetes, with an average duration of diabetes 10.84±6.03 years. All affected eyes were assisted by the same doctor with a non-contact wide-angle lens under the standard three-channel 25G PPV of the flat part of the ciliary body. Five to 7 days before the operation, intravitreal injection of ranibizumab or conbercept 0.05 ml (10 mg/ml) was performed. The incidence of PVH was observed. The age of PVH patients, duration of diabetes, vision before operation, average fasting blood glucose and average postprandial blood glucose before operation, systolic blood pressure and diastolic blood pressure before surgery, laser treatment before surgery, lens removal during operation, intraocular filling during operation, retinal laser points during operation, and fundus lesions during operation (hyperplasia film, Retinal hemorrhage, vascular occlusion, proliferative retinal traction, retinal hiatus, retinal detachment, exudation, neovascularization) were analyzed to find out the cause of PVH. Spearman bivariate correlation analysis and binary logistic regression analysis were performed on the data.ResultsOf the 100 eyes of 87 patients, PVH occurred in 17 eyes (17%). There were statistically significant differences in the number of eyes with vascular occlusion and proliferative traction during surgery in patients with and without PVH (χ2=5.741, 8.103; P<0.05). There was no significant difference in age (t=-1.364), duration of diabetes (t=0.538), preoperative vision (t=1.897), preoperative fasting blood glucose level (t=1.938), preoperative postprandial blood glucose level (t=1.508), preoperative systolic blood pressure (t=-0.571), preoperative diastolic blood pressure (t=0.275), whether received laser treatment (χ2=2.678), the number of laser points during operation (t=0.565), whether received lens removal during operation (χ2=0.331), whether found new blood vessels during operation (χ2=2.741) and whether received intraocular filling during operation (χ2=0.060) between the patients with and without PVH (P>0.05). Spearman's bivariate correlation analysis showed that patients with low vision, poor control of fasting blood glucose levels, vascular occlusion and proliferative retinal traction during the operation were related risk factors for PVH (rs=0.208, 0.229, 0.240, 0.285; P<0.05). Binary logistic regression analysis showed that fundus vascular occlusion and hyperplastic retinal traction may be independent risk factors for PVH during surgery (OR=5.175, 13.915; P<0.05).ConclusionFundus vascular occlusion and retinal traction caused by fibrovascular membrane hyperplasia in PPV may be independent risk factors for PVH in patients with PDR after anti-VEGF drugs combined with PPV.
ObjectiveTo observe the dynamic characteristics of visual acuity after vitrectomy in different sizes of idiopathic macular hole, and analyze the influencing factors.MethodsA retrospective study. From August 2016 to June 2018, 302 patients (302 eyes) with monocular idiopathic macular hole who underwent 25G vitrectomy combined with the internal limiting membrane peeling in Tianjin Eye Hospital were included in the study. There were 130 males and 172 females, with the mean age of 63.36±6.91 years. There were 158 left eyes and 144 right eyes. The logMAR BCVA was 1.13±0.45. The minimum diameter (422.92±211.73 μm) and basal diameter (835.47±366.42 μm) of macular hole and choroid thickness under fovea (244.84±60.68 μm) were measured by OCT. According to the minimum diameter, the holes were divided into small hole group (≤250 μm), middle hole group (>250 μm and ≤400 μm) and large hole group (>400 μm). The logMAR BCVA at 1, 3 and 6 months after surgery in 3 groups were observed. Two-factor repeated measure ANOVA was used to compare the visual acuity of the 3 groups. The generalized estimation equation (GEE) was used to analyze the influencing factors of postoperative visual recovery.ResultsOne month after surgery, all the holes were closed. One, 3 and 6 months after surgery, the logMAR BCVA were 0.33±0.25, 0.23±0.18, 0.16±0.17 in the small hole group; the logMAR BCVA were 0.46±0.25, 0.35±0.26, 0.27±0.28 in the middle hole group; the logMAR BCVA were 0.81±0.51, 0.61±0.48, 0.53±0.37 in the large hole group. Through repeated measurement variance analysis of two factors, it was found that there was an interaction between different groups and different time nodes (F=23.133, P<0.01). All data were segmented and one-way repeated measure ANOVA was performed. The results showed that there was a statistically significant difference in visual acuity between the small hole group and the middle hole group among preoperative and 1 month after surgery (P<0.05), while there was no statistically significant difference in visual acuity between 1, 3 and 6 months after surgery (P>0.05). In the large hole group, among preoperative, 1 months after surgery, 3 months after surgery, the visual acuity difference was statistically significant (P<0.05), while the visual acuity difference between 3 months after surgery and 6 months after surgery was not statistically significant (P>0.05). The results of GEE analysis showed that hole size (χ2=4.17, P=0.04), basal diameter (χ2=7.25, P=0.01), disease course (χ2=19.26, P=0.00), and choroid thickness (χ2=4.19, P=0.04) were the influencing factors of postoperative visual acuity.ConclusionsAfter vitrectomy of macular holes of different sizes, the visual recovery trend is different. The visual recovery of small holes and middle holes is faster and basically restored at 1 month. The large holes requires a slow recovery process and stabilizes vision at 3 months. Hole size, basal diameter, course of disease and choroid thickness are the influencing factors of visual acuity recovery.
Objective To observe the short-term intraocular pressure after 25G+ pars plana vitrectomy (PPV) and analyze the possible influencing factors in rhegmatogenous retinal detachment (RRD) and proliferative diabetic retinopathy (PDR) eyes. Methods This is a retrospective case-control study. A total of 160 patients (163 eyes) of RRD and PDR who underwent 25G+ PPV were enrolled in this study. There were 88 males (89 eyes) and 72 females (74 eyes), with the mean age of (50.37±13.24) years. There were 90 patients (92 eyes) with RRD (the RRD group) and 70 patients (74 eyes) with PDR (the PDR group). Best corrected visual acuity (BCVA) and intraocular pressure (IOP) were performed on all the patients. The BCVA was ranged from hand motion to 0.6. The average IOP was (12.61±4.91) mmHg (1 mmHg=0.133 kPa). There were significant differences in crystalline state (χ2=9.285, P=0.009), IOP (χ2=58.45, P=0.000), history of PPV (χ2=4.915, P=0.027) and hypertension (χ2=24.018, P=0.000), but no significant difference in sex (χ2=0.314, P=0.635) and age (χ2=5.682, P=0.056) between the two groups. A non-contact tonometer has been used to measure IOP on postoperative day 1 and 3. The postoperative IOP distribution has been divided into five groups: severe ocular hypotension (≤5 mmHg), mild ocular hypotension (6 - 9 mmHg), normal (10 - 21 mmHg), mild ocular hypertension (22 - 29 mmHg), severe ocular hypertension (≥30 mmHg). Logistic regression analysis has been used to analyze the risk and protective factors. Results On the first day after surgery, there were 21 eyes (12.9%) in mild ocular hypotension, 96 eyes (58.9%) in normal, 22 eyes (13.4%) in mild ocular hypertension and 24 eyes (14.7%) in severe ocular hypertension. On the first day after surgery, there were 18 eyes (11.0%) in mild ocular hypotension, 117 eyes (71.7%) in normal, 23 eyes (14.1%) in mild ocular hypertension and 5 eyes (3.1%) in severe ocular hypertension. There was no significant difference of IOP distribution between the two groups (Z=−1.235, −1.642; P=0.217, 0.101). The results of logistic regression analysis showed that silicone tamponade was a risk factor for ocular hypertension in PDR eyes on the first day after surgery [odds ratio (OR)=15.400, 95% confidence interval (CI) 3.670 - 64.590; P<0.001], while intraocular lens was the risk factor for ocular hypotension in PDR eyes on third day after surgery (OR=19.000, 95%CI 1.450 - 248.2; P=0.025). As for RRD eyes, the ocular hypotension before surgery was a risk factor for ocular hypertension on the third day after surgery (OR=3.755, 95%CI 1.088 - 12.955; P=0.036). For all eyes, silicone tamponade (OR=0.236, 95%CI 0.070 - 0.797), air tamponade (OR=0.214, 95%CI 0.050 - 0.911) and inert gas tamponade (OR=0.092, 95%CI 0.010 - 0.877) were protective factors for ocular hypotension on the first day after surgery (P=0.020, 0.037, 0.038); silicone tamponade was protective factor for ocular hypotension on the third day after surgery (OR=0.249, 95% CI 0.066 - 0.94, P=0.040); while aphakic eyes was the risk factor for ocular hypotension on third day after surgery (OR=7.765, 95% CI 1.377 - 43.794, P=0.020). The ocular hypotension before surgery was a risk factor for ocular hypertension on the third day after surgery (OR=4.034, 95% CI 1.475 - 11.033, P=0.007). Conclusions The abnormal IOP is common after 25G+ PPV with a rate from 28.3% to 31.1%. Silicone tamponade, air tamponade and inert gases tamponade are protective factors for postoperative ocular hypotension, aphakic eye is risk factor for postoperative ocular hypotension. Ocular hypotension before surgery and silicone oil tamponade are risk factors for postoperative ocular hypertension.
Objective To investigate the prevalence and related factors of diabetic retinopathy (DR) among residents with type 2 diabetes mellitus (T2DM) in Culai Town of Tai'an City in Shandong Province. Methods According to the DM management file database for community, 785 patients with T2DM were randomly selected by cluster sampling method. The questionnaires, routine general examinations, visual and fundus-free fluoroscopy were performed on all the patients. DR diagnosis and classification was according to the guidelines for clinical diagnosis and treatment of DR in China (2014). Both monocular and binocular DR were selected as DR patients, and the worse eye for binocular DR were treated as the DR classification of the patient. The patients were grouped by presence or absence of DR. GraphPad Prism 6, SigmaPlot 12.5, SPSS 20.0 and Excel were used to achieve data analysis. Also, SPSS 20.0 was used for multi-factor logistic regression analysis. Results A total of 699 patients (89.04%) were actually recorded. There were 122 eyes of 63 patients (9.01%) with DR (DR group), 1272 eyes of 636 patients (90.99%) without DR (NDR group). Among the 122 eyes of DR, there were 19 (15.57%), 17 (13.93%), 70 (57.38%), 10 (8.20%), 6 (4.92%) eyes in stage Ⅰ, Ⅱ, Ⅲ, Ⅳ, Ⅴ, respectively. The differences of mean age (t=15 290, P=0.002), DM duration (t=9075, P<0.000) and diastolic blood pressure (t=15 810, P=0.006) between the two groups were statistically significant. There were 23 (36.51%) and 394 (61.95%) patients with hypertension history in the DR group and the NDR group, with the significant difference ( χ2=15.42, OR=0.35, 95%CI 0.21-0.60). There were 57 (90.48%) and 500 (78.62%) patients with fasting blood glucose larger than 6.11 mmol/L in the DR group and the NDR group, with the significant difference (OR=2.51, 95%CI 1.06-5.95, P=0.031). Logistic regression analysis showed that the age, fasting blood glucose and DM duration were influencing factors for DR (OR=1.039, 0.864, 0.898; P=0.021, <0.000, <0.000). Conclusion The prevalence of DR in patients with T2DM in Culai Town of Tai'an City is 9.01%. Age, DM duration, fasting blood glucose are associated to DR. Those with a history of hypertension may have a lower risk of DR than those without a history of hypertension.
ObjectiveTo analyze the status and influencing factors of awareness of diabetic retinopathy (DR) knowledge in diabetics in Funing County, Jiangsu Province. MethodsThis is a cross-sectional study. In 2021, a total of 2 125 residents with diabetes in Funing County, Jiangsu Province were recruited using cluster random sampling methods. General examinations were performed and ophthalmological evaluation were conducted including visual acuity in daily life, slit lamp microscope with preset lens, digital non-mydriatic fundus photography. Clinical assessment and classification of DR were according to the international standard clinical classifications of diabetic retinopathy in 2019. DR was classified into no obvious DR, mild non-proliferative diabetic retinopathy (NPDR), moderate NPDR, severe NPDR and proliferative diabetic retinopathy (PDR). Field questionnaire surveys were conducted to show the awareness rate of DR knowledge. Then Chi-square test and Logistic regression analysis were used to investigate influencing factors. ResultsAmong 2 125 subjects, 762 (35.86%, 762/2 125) residents were male and 1 363 (64.14%, 1 363/2 125) residents were female. A total of 444 (20.89%, 444/2 125) subjects were diagnosed as DR. Among which, 438 (20.61%, 438/2 125) subjects were NPDR, 6 (0.28%, 6/2 125) subjects were PDR. A total of 419 (19.72%, 419/2 125) subjects were diagnosed as cataract. The topic awareness rates were all below 45.00%. The overall population awareness rate was 19.45% (4 959/25 500). Awareness rate was correlated with age, visual acuity in daily life, education level, family history of diabetes, diabetic retinopathy grades and the type of treatment for diabetes (P<0.001). Logistic regression analysis showed that the knowledge rate of prevention and treatment of DR Decreased significantly in patients aged 60-79 compared with those aged under 50 (P<0.05). Compared with those with visual acuity<0.1 in daily life, the knowledge rate of DR prevention and treatment in those with visual acuity≥0.1 was significantly decreased (P<0.05). While primary school to college education, with family history of diabetes, with DR, oral hypoglycemic agents and/or insulin treatment were associated with higher awareness rate (P<0.05). ConclusionsThe DR knowledge level is low among diabetics in Funing County, Jiangsu Province in 2021. Age, visual acuity in daily life, education level, family history of diabetes, with DR and receiving drug treatments are main influencing factors for diabetic’s awareness.
ObjectiveTo observe the effect of intravitreal injection of conbercept in the treatment of retinopathy of premature (ROP) and to analyze the factors related to the therapy.MethodsA retrospective study. A total of 57 patients (57 eyes) with pre-threshold type 1 (30 patients, 30 eyes), threshold ROP (21 patients, 21 eyes) and acute aggressive posterior ROP (APROP, 6 patients, 6 eyes)) from premature infants by retinal screening in Henan Provincial People’s Hospital during October 2017 and June 2018 were enrolled in this study. All children were received routinely intravitreal injected 10 mg/ml conbercept 0.025 ml (0.25 mg) within 24 hours after diagnosis. Fundus examination was performed 7 days after injection. The interval of examination was 1−3 weeks according to fundus conditions. The mean follow-up was 30.1±4.6 weeks. For patients with relapse or no response to treatment, repeated intravitreal injection of conbercept or laser photocoagulation therapy was given. The retinal blood vessels of the affected eyes were observed. Logistic stepwise regression analysis was used for the correlation test of multiple factors.ResultsAmong 57 eyes, 49 eyes and 8 eyes were treated with 1 or 2 times of intravitreal injection of conbercept. After 24 weeks of treatment, in 57 eyes, 26 eyes were cured (45.6%), 22 eyes improved (38.6%), 8 eyes relapsed (14.0%), and 1 eye aggravated (1.8%). The recurrence time was 12.9±4.5 weeks after the first injection, and the corrected gestational age was 49.0±6.7 weeks. There were significant differences in initial injection time, lesion range among the cure, improved and recurrence eyes (F=5.124, 7.122; P<0.01, <0.01). Parameters of ROP condition, including ROP diagnosis (pre-threshold type 1, threshold and APROP), zone (zone 1 and 2), stage (stage 2 and 3) and plus lesions, were significant different among the cure, improved and recurrence eyes (χ2=11.784, 14.100, 6.896, 9.935; P<0.01, <0.01, <0.05, <0.01). Logistic stepwise regression analysis showed that the recurrence rate was correlated with ROP zone, more likely recurrence at zone 1 than zone 2 (Wald=9.879, OR=27.333, P=0.002). No injection-related complications such as endophthalmitis, cataract and glaucoma were found during treatment and follow-up period.ConclusionsIntravitreal injection of conbercept is effective in the treatment of ROP without obvious adverse reactions. Lesion zoning is associated with recurrence after treatment.
ObjectiveTo observe and preliminary investigate the influencing factors of exudative retinal detachment in patients with severe preeclampsia (S-PE) and its influence on pregnancy outcome.MethodsA total of 89 patients of S-PE patients diagnosed in Department of Obstetrics in The Third Central Hospital of Tianjin from July 2018 to June 2020 were included in this study. According to whether the patients were complicated with exudative retinal detachment, they were divided into retinal detachment group (43 cases) and non retinal detachment group (46 cases). All patients underwent direct ophthalmoscopy, and those with suspected or definite retinal detachment underwent optical coherence tomography or B-mode ultrasonography. The age, course of disease, body mass index, systolic blood pressure, diastolic blood pressure, laboratory serum albumin level, 24 h urinary protein, platelet count, mean platelet volume, platelet distribution width and serum uric acid content were collected. The average age (t=−1.01), body mass index (t=−1.799), course of disease (t=−1.657) and constituent ratio of primipara and multipara in the two groups were compared (χ2=1.411), the difference was not statistically significant (P>0.05). The end of pregnancy time, systemic complications, fetal outcomes and neonatal Apgar scores were analyzed, retrospectively. Independent sample t test was used to compare the quantitative data between the two groups; Chi square test was used to compare qualitative data. Binary logistic regression analysis to screen the influencing factors of exudative retinal detachment in S-PE.ResultsSystolic blood pressure and diastolic blood pressure were higher in the retinal detachment group than in the non retinal detachment group, and the difference was statistically significant (t=2.087, 2.810; P=0.040, 0.006). Serum albumin (t=−10.404), 24-hour urinary protein quantification (t=6.401), blood uric acid (t=3.910), platelet count (t=−6.124) and platelet distribution width (t=2.992) were compared between the two groups, and the differences were statistically significant (P<0.05). There were 30 (69.77%, 30/43) cases in retinal detachment group and 14 (30.43%, 14/46) cases in non retinal detachment group with severe systemic complications; The average time of ending pregnancy was 34.66±3.29 and 38.25±1.62 weeks; The average Apgar scores at birth were 7.28±3.40 and 9.46±1.59. The incidence of severe systemic complications in two groups (χ2=13.755), the end of pregnancy time (t=−6.448), Apgar score at birth (t=−3.824), the differences were statistically significant (P=0.000、0.000、0.000). Fetal distress and death were 8 (18.60%, 8/43), 7 (16.28%, 7/43) and 7 (15.22%, 7/46), 1 (2.17%, 1/46) in retinal detachment group and non retinal detachment group respectively. There was no significant difference in the incidence of fetal distress between the two groups (χ2=0.182, P=0.670). The difference of fetal mortality was statistically significant (P= 0.027). Logistic regression analysis showed that serum albumin and uric acid were associated with exudative retinal detachment in patients with S-PE (P<0.05).ConclusionsSerum albumin and uric acid are the influencing factors of exudative retinal detachment in patients with S-PE. Patients with exudative retinal detachment are prone to adverse pregnancy outcomes.
Objective To investigate the factors associated with short-term elevation of intraocular pressure after ranibizumab intravitreal injection. Methods 292 eyes of 292 patients who were diagnosed retinopathy and suitable to receive ranibizumab intravitreal injection were enrolled in this prospective clinical study. There were 157 males and 135 females. 193 patients diagnosed with age-related macular degeneration and 99 other retinopathy patients. Mean age of patients was 62.75±13.74 years. All subjects underwent systemic and comprehensive ophthalmology examinations. The mean BCVA was 0.68±0.47 logMAR. Mean basal intraocular pressure was 18.1 mmHg (1 mmHg=0.133 kPa). All patients received intravitreal injection with 0.05 ml of ranibizumab (0.5 mg). The intraocular pressure were measured by non-contact tonometer at 10, 30, 120 minutes and 1 day after injection in a sitting position. The patients were grouped by the changes of intraocular pressure 10 minutes after injection. The elevation was more than 10 mmHg as elevation group and less than 10 mmHg as stable group. Analyze the possible related factors with elevation of intraocular pressure after ranibizumab intravitreal injection by comparing the different datum of two groups. Results The mean intraocular pressure were 23.8, 20.5, 19.9 and 17.4 mmHg at 10, 30, 120 minutes and 1 day after injection. The significant elevation level were 5.8, 2.4, 1.8, −0.7 mmHg compared with basal intraocular pressure. Among 292 eyes, intraocular pressure elevation in 68 eyes and stabled in 224 eyes. The age (Z=−0.732), gender (χ2=1.929), right or left eye (χ2=2.910), BCVA (Z=−0.039), diseases (χ2=2.088) were no significant difference between two groups (P>0.05). The injection number (Z=−2.413, P=0.001), basal intraocular pressure (Z=−3.405, P=0.016) and elevations after injection (Z=−11.501, −8.366, −5.135, −3.568; P<0.01) were significantly different comparing two groups (P<0.05). By logistic regression analysis, basal intraocular pressure was positively correlated with the elevation of intraocular pressure 10 minutes after injection (B=−0.844, OR=0.43, 95%CI 0.24−0.76, P=0.004). Patients with higher basal intraocular pressure may occur intraocular pressure elevation after ranibizumab intravitreal injection much probably. Conclusions The factors associated with short-term elevation of intraocular pressure after ranibizumab intravitreal injection were basal intraocular pressure. The higher basal intraocular pressure, the higher risk to gain elevation of intraocular pressure after injection.
Objective To analyze the causes for day surgery cancellations before admission or on the same day of operation, and put forward targeted measures to improve the medical resource utilization and patient satisfaction. Methods The basic information and clinical data of patients who had been scheduled for surgery in the Day Surgery Center of West China Hospital, Sichuan University between January 2018 and September 2021 were collected. The reasons for the surgery cancellations before admission or on the same day of operation were analyzed. Results From January 2018 to September 2021, a total of 45176 patients were successfully scheduled for day surgery, and 44300 patients completed surgery as planned. A total of 876 operations (1.94%) were cancelled after being scheduled, including 546 (1.21%) before admission and 330 (0.73%) on the surgery day. Ranked from high to low according to the cancellation rates, the top five departments were Department of Dermatology, Department of Vascular Surgery, Department of Hepatobiliary Surgery, Department of Otorhinolaryngology, Head and Neck Surgery, and Department of Gastroenterology, with a cancellation rate of 3.38% (8/237), 2.90% (25/863), 2.85% (101/3548), 2.48% (171/6893), and 1.91% (260/13578), respectively. In the reasons for cancellations, patient factors accounted for 57.31% (502/876) and medical management factors accounted for 42.69% (374/876). Conclusions The cancellations of day surgery mainly occur before admission, and are mainly caused by patient factors. It is necessary to strengthen the preoperative education for day surgery patients, and enhance the communication and cooperation between surgery physicians, nurses and technicians, in order to reduce the operation cancellation rate and make reasonable and efficient use of medical resources.