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NB Paper Clarifies, As Far As Possible

posted Apr 28, 2015, 6:18 AM by Frank O'Brien   [ updated Jul 2, 2015, 5:10 AM ]
Don Quixote tilting at windmills
In some ways, the advice in Annex ZA from 
EN ISO 14971:2012 can seem a bit like Don Quixote tilting at windmills and dreaming the impossible dream.  Do we want to reduce risk until further reduction is impossible?

Annex ZA correctly reminds us that the the threshold of risk acceptability is not arbitrary, set from manufacturer to manufacturer, but instead a single threshold expected by society.  The threshold for risk acceptability must be compatible with the high level of protection of health and safety expected of society.  

Not clear from Annex ZA is a recognition that the threshold necessarily takes into account technical and economic limits.  The goal is to be free from unacceptable risk.  Delaying a medical device to make it safer than expected by society, can result in patient harm from lack of access, and additional economic costs.

Here's the background.  Annex ZA, of EN ISO 14971:2012, outlines the following key discords/incompatibilities between ISO 14971 and the Essential Requirements of the Medical Device Directive, 93/42/EEC
  1. Reduce risk as far as possible (AFAP) is not to include economic constraints;
  2. All individual risks and the overall risk, even those judged acceptable, need to be justified with benefit;
  3. Informing users of residual risks is not a risk control/reduction measure.

The Essential Requirements 1 and 2 of the Medical Device Directive, 93/42/EEC, say, "reduce risks as far as possible" (AFAP).  EN ISO 14971:2009, the European version of the Risk Management standard, ISO 14971:2007, has been considered the harmonized standard, which would allow presumption of compliance with these ER's.  With the release of EN ISO 14971:2012 this had come into doubt.

Here's what's new.  With the release of the "interim" Consensus Paper for the Interpretation and Application of Annexes Z in EN ISO 14971: 2012, Version 1.1, 13 October 2014, from the Notified Bodies Recommendation Group, we now have better guidance on these issues.  The paper clarifies Annex ZA:
  1. AFAP realistically takes into account technical and economic constraints (and opportunities). AFAP is dependent on Safety Principals, such as Regulations, Standards and the generally acknowledged state of the art (GASOTA), which take into account technical and economic constraints and improvements. 
  2. Individual acceptable risks do not need to be justified with benefit, but it is expected that the overall residual risk (of the cumulative individual residual risks) needs to be justified with benefit, which is not unusual for most medical devices.  
  3. Informing users of residual risk, for purposes of "disclosing risk" so doctors/patients/their families can make risk benefit decisions is not a risk control measure.  Providing "information for safety", such as marking on product, instructions, or training, is considered a risk control measure, when validated as part of a usability engineering process.

The paper indicates that Notified Bodies auditors will check that:
  1. Risk (including acceptable risk) is reduced AFAP consistent with safety principles.  Risk reduction must use a hierarchy of techniques: inherent design, protective measures, and last, information for safety.  
  2. Overall residual risk must be justified with benefit.
  3. Information for Safety must be validated as effective.  Where appropriate, disclosure of risk is provided.
Manufacturers need to review their risk policy and procedures to confirm consistency with these safety principals.  As long as risk acceptability decisions are based on safety principals, such as Regulations, Standards and GASOTA, in the context of AFAP, “possible”, “feasible” and/or “practicable” have the same meaning.  Standards that provide a presumption of acceptable risk include the medical electrical equipment safety standard, IEC 60601/ISO 80601.