title: Assessment of cataract surgical outcomes in settings where follow-up is poor: PRECOG, a multicentre observational study.
abstract: BACKGROUND
  Poor follow-up after cataract surgery in developing countries makes assessment of operative quality uncertain. We aimed to assess two strategies to measure visual outcome: recording the visual acuity of all patients 3 or fewer days postoperatively (early postoperative assessment), and recording that of only those patients who returned for the final follow-up examination after 40 or more days without additional prompting.
  
  
  METHODS
  Each of 40 centres in ten countries in Asia, Africa, and Latin America recruited 40-120 consecutive surgical cataract patients. Operative-eye best-corrected visual acuity and uncorrected visual acuity were recorded before surgery, 3 or fewer days postoperatively, and 40 or more days postoperatively. Clinics logged whether each patient had returned for the final follow-up examination without additional prompting, had to be actively encouraged to return, or had to be examined at home. Visual outcome for each centre was defined as the proportion of patients with uncorrected visual acuity of 6/18 or better minus the proportion with uncorrected visual acuity of 6/60 or worse, and was calculated for each participating hospital with results from the early assessment of all patients and the late assessment of only those returning unprompted, with results from the final follow-up assessment for all patients used as the standard.
  
  
  RESULTS
  Of 3708 participants, 3441 (93%) had final follow-up vision data recorded 40 or more days after surgery, 1831 of whom (51% of the 3581 total participants for whom mode of follow-up was recorded) had returned to the clinic without additional prompting. Visual outcome by hospital from early postoperative and final follow-up assessment for all patients were highly correlated (Spearman's rs=0·74, p<0·0001). Visual outcome from final follow-up assessment for all patients and for only those who returned without additional prompting were also highly correlated (rs=0·86, p<0·0001), even for the 17 hospitals with unprompted return rates of less than 50% (rs=0·71, p=0·002). When we divided hospitals into top 25%, middle 50%, and bottom 25% by visual outcome, classification based on final follow-up assessment for all patients was the same as that based on early postoperative assessment for 27 (68%) of 40 centres, and the same as that based on data from patients who returned without additional prompting in 31 (84%) of 37 centres. Use of glasses to optimise vision at the time of the early and late examinations did not further improve the correlations.
  
  
  CONCLUSIONS
  Early vision assessment for all patients and follow-up assessment only for patients who return to the clinic without prompting are valid measures of operative quality in settings where follow-up is poor.
  
  
  BACKGROUND
  ORBIS International, Fred Hollows Foundation, Helen Keller International, International Association for the Prevention of Blindness Latin American Office, Aravind Eye Care System.
authors.affiliation: Preventive Ophthalmology and State Key Laboratory, Zhongshan Ophthalmic Centre, Sun Yat-sen University, Guangzhou, China; ORBIS International, New York, NY, USA. Electronic address: ncongdon1@gmail.com.
authors.forename: Nathan
authors.initials: N
authors.lastname: Congdon
authors.affiliation: Preventive Ophthalmology and State Key Laboratory, Zhongshan Ophthalmic Centre, Sun Yat-sen University, Guangzhou, China.
authors.forename: Xixi
authors.initials: X
authors.lastname: Yan
authors.affiliation: International Agency for the Prevention of Blindness/VISION 2020 Latin America Regional Office, Miami, FL, USA.
authors.forename: Van
authors.initials: V
authors.lastname: Lansingh
authors.affiliation: ORBIS International, New York, NY, USA.
authors.forename: Alemayehu
authors.initials: A
authors.lastname: Sisay
authors.affiliation: Fred Hollows Foundation, Sydney, NSW, Australia; WHO Western Pacific Region Office, Manila, Philippines.
authors.forename: Andreas
authors.initials: A
authors.lastname: Müller
authors.affiliation: Brien Holden Vision Institute, Sydney, NSW, Australia.
authors.forename: Ving
authors.initials: V
authors.lastname: Chan
authors.affiliation: Preventive Ophthalmology and State Key Laboratory, Zhongshan Ophthalmic Centre, Sun Yat-sen University, Guangzhou, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Jin
authors.affiliation: Preventive Ophthalmology and State Key Laboratory, Zhongshan Ophthalmic Centre, Sun Yat-sen University, Guangzhou, China.
authors.forename: Mirjam E
authors.initials: ME
authors.lastname: Meltzer
authors.affiliation: Lions Aravind Institute of Community Ophthalmology, Aravind Eye Care System, Madurai, India.
authors.forename: Sasipriya M
authors.initials: SM
authors.lastname: Karumanchi
authors.affiliation: Fred Hollows Foundation, Sydney, NSW, Australia.
authors.forename: Chunhong
authors.initials: C
authors.lastname: Guan
authors.affiliation: ORBIS International, New York, NY, USA.
authors.forename: Quy
authors.initials: Q
authors.lastname: Vuong
authors.affiliation: International Agency for the Prevention of Blindness/VISION 2020 Latin America Regional Office, Miami, FL, USA.
authors.forename: Nelson
authors.initials: N
authors.lastname: Rivera
authors.affiliation: ORBIS International, New York, NY, USA.
authors.forename: Joan
authors.initials: J
authors.lastname: McCleod-Omawale
authors.affiliation: Preventive Ophthalmology and State Key Laboratory, Zhongshan Ophthalmic Centre, Sun Yat-sen University, Guangzhou, China; Helen Keller International, New York, NY, USA.
authors.forename: Mingguang
authors.initials: M
authors.lastname: He
mesh_terms: D000328:Adult; D000359:Aftercare / Q000706:statistics & numerical data; D000368:Aged; D002387:Cataract Extraction / Q000592:standards*; D003906:Developing Countries / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011182:Postoperative Care / Q000592:standards*; D014792:Visual Acuity