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Improving health worldwide www.iceh.org.uk www.lshtm.ac.uk Calculation of CSR and CSC and visual acuity thresholds Improving health worldwide www.iceh.org.uk www.lshtm.ac.uk IAPB 9GA Hyderabad 2012 G V S Murthy
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Calculation of CSR and CSC and visual acuity thresholds

Feb 23, 2016

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Ahmed Akrout

Calculation of CSR and CSC and visual acuity thresholds. IAPB 9GA Hyderabad 2012. G V S Murthy. Improving health worldwide. Improving health worldwide. www.iceh.org.uk www.lshtm.ac.uk. www.iceh.org.uk www.lshtm.ac.uk. Institutional Affiliation. Reader, - PowerPoint PPT Presentation
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Page 1: Calculation of CSR and CSC and visual acuity thresholds

Improving health worldwidewww.iceh.org.uk www.lshtm.ac.uk

Calculation of CSR and CSC and visual acuity thresholds

Improving health worldwidewww.iceh.org.uk www.lshtm.ac.uk

IAPB 9GA Hyderabad 2012

G V S Murthy

Page 2: Calculation of CSR and CSC and visual acuity thresholds

Improving health worldwidewww.iceh.org.uk www.lshtm.ac.uk

Reader, International Centre for Eye Health, Department of Clinical Research, Faculty of Infectious and Tropical Diseases , London School of Hygiene and Tropical Medicine&

Director, Indian Institute of Public Health, Public Health Foundation of India, Hyderabad

Institutional Affiliation

Page 3: Calculation of CSR and CSC and visual acuity thresholds

Acknowledgements

• Dr Hans Limburg

• Dr B R Shamanna

Their inputs were critical to this presentation

Page 4: Calculation of CSR and CSC and visual acuity thresholds

Characteristics• Cataract Surgical Rate (CSR) uses the

population as the denominator

• Cataract Surgical Coverage (CSC) uses operated persons in the community as the denominator.

• Both can be used in conjunction to compare performance and pending workload at regional/ national level.

Page 5: Calculation of CSR and CSC and visual acuity thresholds

Cataract Surgical Rate (CSR) Number of cataract operations (eyes) conducted

per million population per year

• Indicator for output on cataract intervention• Denominator is total population while cataract occurs

mainly in people 50+• Who is operated? (age, sex, 1st or 2nd eye, VA?)• Depends on accuracy of data collection• Risk of over- or under-reporting

Page 6: Calculation of CSR and CSC and visual acuity thresholds

What data is needed to calculate CSR?

• Population of administrative area

• Quantum of cataract surgeries (operated eyes)

• Time period when above events occur – i.e.

specific year

• Usually obtained from secondary data sources.

Page 7: Calculation of CSR and CSC and visual acuity thresholds

Cataract Surgical Rate

No. of Cataract Surgeries/ Year x 106

Population in Defined Area

Cataract Surgeries refers to Operated Eyes

Page 8: Calculation of CSR and CSC and visual acuity thresholds

Cataract Surgical Coverage (CSC)Objective:• coverage indicator • measures accessibility & utilization of services• measures actual community level situation • independent of reporting system

Assumption:- VA at time of surgery not known: use VA threshold

conforming to surgical practice in survey area

Page 9: Calculation of CSR and CSC and visual acuity thresholds

Cataract Surgical coverage

Sources of Data:

– Surveys

– RACSS/RAAB

Page 10: Calculation of CSR and CSC and visual acuity thresholds

What data is needed to calculate CSC?

• No. of cataract blind/visually impaired

• Quantum of cataract surgeries (eyes/persons)

• Time period when above events occur – i.e. specific

year

• Valid data generally possible only from primary sources

in LMIC . i.e. RAAB

Page 11: Calculation of CSR and CSC and visual acuity thresholds

Defining CSC• Can be calculated at person level or operated eye level

• Can be calculated at different visual acuity levels (based on a country’s needs/ surgical practices)

– VA<3/60: cataract blind eye or person– VA<6/60: severely visually impaired cataract eye or

person– VA<6/18: visually impaired cataract eye or person

Page 12: Calculation of CSR and CSC and visual acuity thresholds

Calculating CSCCSC eyes: (a/a+b) x 100Where:a = no. (pseudo)aphakic eyesb = no. eyes with operable cataract (BCVA<3/60; <6/60; <6/18)

CSC persons: (x + y/x + y + z) x 100Where:x = persons with bilateral (pseudo)aphakiay = persons with 1 (pseudo)aphakic and 1 operable cataractz = persons with bilateral operable cataract (BCVA<3/60; <6/60; <6/18)

Page 13: Calculation of CSR and CSC and visual acuity thresholds

THANK YOU