You’ve seen the five-star badges. Maybe you’ve picked a plan because it had a shiny 4.5 on a government or industry site. But beneath those public stars live quieter — and often more useful — signals: complaint indices, claims- and prior-authorization-denial rates, accreditation details and regional satisfaction surveys. Those “hidden” ratings often expose the insurers that consistently frustrate members, deny claims, or make care harder to access — long before price or marketing gives them away.

This guide walks you through the full scoreboard: what the different ratings actually measure, how to find the red flags, and how to use that intelligence to avoid the insurers with the worst performance for your needs. I researched the official metrics and independent surveys so you can cut through the marketing and shop like someone who knows where insurers hide their worst numbers.

Quick links (used in the post)

• Learn how Medicare star ratings work: CMS — Medicare Advantage & Part D Star Ratings (2025). (Centers for Medicare & Medicaid Services)
• See state-level complaint/complaint-index data: NAIC — Health Complaint Index (sample report). (Government of India)

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TL;DR — What you should know right away

• Official five-star systems (CMS, NCQA) matter — but they’re not the whole story. They measure specific plan types and quality domains; they don’t capture everything members experience. (Centers for Medicare & Medicaid Services)
• Complaint indices and complaint ratios (NAIC and state DOI reports) are a blunt — and highly valuable — signal of trouble. They often reveal plans with chronic customer-service issues even when star scores look okay. (Government of India)
• Claims and prior-authorization denial rates are among the strongest real-world indicators that a plan will be difficult to use; denial rates vary widely by insurer and by plan. (KFF)
• No single data point is decisive. Use a quick checklist: star ratings (if applicable), NCQA report card, complaint index, prior authorization/denial data, J.D. Power or member-satisfaction surveys, and local provider feedback. (J.D. Power)

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Why these ratings are “hidden” — and why that matters

When people say “star ratings,” they usually mean the big, visible systems:

• Medicare Advantage & Part D stars (CMS) for Medicare plans. (Centers for Medicare & Medicaid Services)
• NCQA’s Health Plan Ratings (HEDIS + CAHPS) that show quality for commercial, Medicaid and Medicare plans. (NCQA)

But beyond those are operational and regulatory metrics insurers rarely promote:

• Complaint Index / Complaint Ratio (NAIC & state departments of insurance): counts complaints relative to company size and premium — a normalized “how many people complain per dollar size” metric. (Government of India)
• Claims denial rates (initial denials, overturned appeals): if an insurer denies a high share of claims, you’ll likely see surprise bills and long appeals. (Health Affairs)
• Prior authorization denial rates: insurers vary — some deny a few percent of requests, others deny double-digit shares; that affects access to diagnostics, procedures and medications. (KFF)
• Regional satisfaction and experience scores (J.D. Power, CAHPS): reveal service problems not captured by clinical metrics. (J.D. Power)

These secondary metrics are “hidden” because they’re technical, scattered across government reports and regulator data, or buried behind paywalls. But they’re often better predictors of daily headaches than a single “overall” star.

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How each major rating works (and what its weaknesses are)

Below I break down the main public and hidden measures you’ll encounter and what they actually tell you.

1. CMS Medicare Advantage & Part D Star Ratings — what they are

• Who they cover: Medicare Advantage (Part C) and Part D prescription drug plans. Not directly relevant for most commercial or Medicaid plans. (Centers for Medicare & Medicaid Services)
• What they measure: dozens of measures across clinical outcomes, prevention, member experience (CAHPS) and customer service; scores are aggregated into 1–5 stars. (Centers for Medicare & Medicaid Services)
• Why they matter: they determine bonus payments to plans, affect enrollment tools and are widely used by beneficiaries to compare plans. (Centers for Medicare & Medicaid Services)
• Weaknesses: star ratings change annually based on methodology; a plan’s star can drop due to measurement changes rather than service changes. Legal disputes over methods are not unusual. (Reuters)

2. NCQA Health Plan Ratings — what they are

• Who they cover: commercial, Medicare and Medicaid managed care plans. The score combines HEDIS clinical measures and CAHPS member-experience results; accreditation adds bonus points. (NCQA)
• What they measure: clinical quality (immunizations, chronic-disease control, screenings) and member experience. (NCQA)
• Why they matter: NCQA is often used by employers, state purchasers, and consumer advocates to judge plan quality. (NCQA)
• Weaknesses: NCQA scores don’t show how the insurer handles claims, prior authorization fights, or the member-service phone experience in minute detail.

3. NAIC Complaint Index & state DOI complaint reports — the regulator’s scoreboard

• Who they cover: every insurer subject to state regulation; NAIC aggregates complaint volumes and produces a complaint index that normalizes complaints by company size. (Government of India)
• What they measure: consumer complaints by category (claims, billing, denials, customer service), normalized for company premium. High complaint index = more complaints than expected for size. (Government of India)
• Why they matter: complaints are direct, unfiltered signals from customers and providers. Repeated patterns across states are revealing. (Government of India)
• Weaknesses: raw complaints are not adjudicated findings — but state DOIs often report “confirmed” complaints after investigation.

4. Member satisfaction / private surveys (J.D. Power, consumer research)

• Who they cover: commercial and Medicare populations; surveys sample members on specific experience dimensions (customer service, claims, provider access). (J.D. Power)
• What they measure: member-reported satisfaction and real-world experience — the things people care about (ease of claims, access, clarity of bills). (J.D. Power)
• Why they matter: measures the lived experience not captured in clinical metrics. (J.D. Power)
• Weaknesses: sample sizes and regional differences mean an insurer can rank high in one state and low in another.

5. Claims and prior authorization denial data — the most operational measure

• What they measure: how often plans deny requests (PA denials) or initial claims, and how often denials are overturned on appeal. High denial rates = hassle and delays. (KFF)
• Why they matter: a plan that denies a lot of claims is functionally harder to use, even if its preventive care scores are fine. (Commonwealth Fund)
• Weaknesses: denial is sometimes appropriate for fraud control or incorrect billing, so context matters — but very high denial rates are a legit red flag. (American Hospital Association)

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The scoreboard: compare the metrics at a glance (table)

This table shows the key rating types, what they measure, where to look, a simple “red flag” threshold, and an example or two drawn from recent reports/sources.

Metric	What it measures	Where to find it	Red-flag threshold (quick rule of thumb)	Example / note
CMS MA & Part D Star Ratings	Quality & member experience for Medicare plans (1–5 stars)	CMS Star Ratings fact sheets / Medicare Plan Finder.	≤ 3.0 stars for a contract = worry, especially <2.5.	Large carriers’ averages vary; Centene had the lowest average among largest insurers in 2025 data. (Centers for Medicare & Medicaid Services)
NCQA Health Plan Ratings	HEDIS clinical measures + CAHPS member experience	NCQA Health Plan Ratings page & report cards.	≤ 2 stars (NCQA) indicates poor performance on clinical & experience measures.	In 2024, 13 of 1,019 plans scored ≤2 stars. (NCQA)
NAIC Complaint Index / State DOI complaints	Consumer complaints normalized by premium/company size	NAIC complaint index reports & state DOI complaint PDFs.	Complaint index significantly >1 (or “top of list” by count) = consistent trouble.	NAIC lists companies with high complaint indices (see NAIC sample report). (Government of India)
Prior authorization denial rate	Share of PA requests denied (full or partial)	KFF analyses / CMS disclosures / research articles	Denial rate > ~10% (varies) = problematic for access.	KFF reported insurer denial rates from ~3.5% (Humana) up to 13.6% (Centene) in 2023. (KFF)
Initial claims denial rate	% of initial claims denied before appeal	Industry reports, Health Affairs, AHA, provider surveys	Initial denial rate > ~12% is concerning (industry averages vary).	Recent studies show initial denial rates rising into low-teens for many payers. (Health Affairs)
Member satisfaction surveys	Member-reported experience (ease, communication, claims)	J.D. Power, CAHPS reports	Scores far below regional average, or consistent bottom quartile	J.D. Power shows meaningful satisfaction gaps across carriers and regions. (J.D. Power)

(Notes: “Red-flag thresholds” are practical rules of thumb, not hard thresholds — thresholds vary by region, market and the specific measure methodology.)

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Real examples — where the data pointed to problems

Rather than accuse companies wholesale, look for consistent signals across multiple metrics. Here are representative, cited findings that illustrate how the hidden ratings expose weak performers:

• Centene and lower Medicare averages: among the largest insurers, Centene’s portfolio had the lowest average Medicare Advantage star rating in the 2025 CMS data — a sign that some of its contracts perform substantially below peers. (Becker’s Payer Issues | Payer News)
• High prior-authorization denial rates reveal access friction: KFF’s 2023 analysis showed wide variation in prior authorization denial rates across Medicare Advantage carriers — Humana denied about 3.5% of PA requests while Centene denied ~13.6%, indicating very different experiences for members depending on carrier. High PA-denial insurers can create repeated care delays. (KFF)
• Plans with low NCQA scores exist: NCQA’s 2024 ratings identified plans with very low ratings (13 plans scored 2 stars or less), demonstrating that some plans perform poorly on both care quality and member experience. (NCQA)
• Complaint data signals chronic problems: NAIC/state DOI complaint indices sometimes show a small number of companies with many complaints relative to their size — an immediate red flag for customer-service or claims issues. (See NAIC complaint index sample.) (Government of India)

Those examples show the pattern: an insurer might look OK on one public score but reveal problems when you dig into operational metrics. That’s why it pays to consult more than one signal.

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How to use these ratings when you’re choosing a plan (step-by-step)

If you’re shopping health plans (Medicare, Marketplace, employer, or Medicaid managed care), use this checklist so you don’t get blindsided:

1. Start with the appropriate official rating
   • Medicare: check the CMS star ratings and Medicare Plan Finder. (Centers for Medicare & Medicaid Services)
   • Commercial/Medicaid: check NCQA report cards. (NCQA)
2. Check complaint data
   • Search the NAIC complaint index or your state DOI’s complaint reports for the carrier/plan. A high complaint index or many complaint types (especially claims/billing) = caution. (Government of India)
3. Look up prior-authorization and denial statistics
   • For Medicare Advantage and many employer plans, KFF and other analyses publish PA and denial rates. If a carrier denies >10% of PA requests, count that as a red flag for access friction. (KFF)
4. Scan member-satisfaction surveys
   • If J.D. Power or local CAHPS surveys rank the insurer in the bottom region, that’s meaningful on customer service and claims handling. (J.D. Power)
5. Ask local providers about networks & denials
   • Call a few doctors’ offices in your area and ask which insurers are hardest to work with or have the slowest claims turnaround. Providers often see denial patterns before consumers do.
6. Read plan materials for prior authorization “strings”
   • Look for broad PA requirements, narrow drug-formulary carve-outs, and limited specialist access clauses. If many core services require prior auth, expect more fights.
7. Check appeals success rates if available
   • Some analyses show what share of denials are overturned on appeal. Low overturn rates plus high denial rates = trouble.
8. Consider financial strength and accreditation
   • NCQA accreditation, AM Best financial ratings and CMS “special enrollments” signals add context. A plan with good financials but poor service might change behavior slowly; a weak financial rating suggests risk of future provider access problems.

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A short guide to interpreting complaint-index numbers

Complaint indices look intimidating, but here’s how to read them quickly:

• What the index does: it adjusts raw complaint counts for company size (premium volume). A small company with 10 complaints could look worse than a giant with 100 — the index normalizes that. (Government of India)
• What a high index means: more complaints than expected for a company of that size. It doesn’t mean the company is guilty — but repeating high indexes across years or across states is a clear warning. (content.naic.org)
• Where to find details: state Department of Insurance websites and the NAIC consumer complaint search tools publish complaint codes (e.g., claims handling, denials, billing). Those codes tell you the type of problems consumers report. (content.naic.org)

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Red flags (quick checklist to avoid the worst providers)

Watch for any of these signals — one is worth caution, a cluster means you should probably switch plans:

• High complaint index in your state or nationally (NAIC/state DOI). (Government of India)
• Low NCQA rating (≤ 2) or consistently poor HEDIS/CAHPS scores. (NCQA)
• CMS star rating ≤ 3 for Medicare Advantage contracts you’d consider. (Centers for Medicare & Medicaid Services)
• Prior authorization denial rates in double digits (or a carrier near the top of denial lists). (KFF)
• Claims denial rates well above industry averages (initial denials into the teens). (Health Affairs)
• Persistent negative results in member satisfaction surveys (J.D. Power, CAHPS). (J.D. Power)
• Local provider reports that the plan is slow to pay or routinely requires appeals.

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How insurers “hide” problems from the average shopper (and the fixes)

Insurers use several tactics — intentionally or not — that make shopping by price alone risky:

• Narrow networks and selective plan offerings: a plan with great preventive-care scores may still have a very narrow network in your ZIP code, forcing out-of-network care or referrals. Always check the actual provider list. (Investopedia)
• Fragmented metrics across product lines: a carrier can have a 4-star Medicare plan and simultaneously run lower-quality Marketplace or Medicaid plans; data are often reported by plan contract, not at the parent-company level, so averages can hide poor performers. (Becker’s Payer Issues | Payer News)
• Methodology changes that mask decline: rating agencies periodically change cut points or measures (CMS has updated MA star methodology in 2024–2025), so a drop might reflect new rules rather than sudden service failure — but repeated or large drops are meaningful. (Centers for Medicare & Medicaid Services)
• Low appeals visibility: some insurers make appeals difficult (complex forms, slow processing), which suppresses overturned denials and hides true denial harm. Look for data on appeal volumes and overturn rates. (KFF)

Fixes: regulators are starting to force more transparency (CMS disclosures, insurer commitments to publish PA data), and advocacy groups push for simpler appeals. But until full transparency arrives, your best defense is triangulating several sources.

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Step-by-step: how I would evaluate a specific insurer (example workflow)

If I were choosing a plan tomorrow in my county, I’d do this:

1. Select the plan type (Medicare/Marketplace/Employer/Medicaid). Different rating systems apply.
2. Check the top-level public score: CMS stars (Medicare) or NCQA (commercial/Medicaid). Note year and any recent methodology changes. (Centers for Medicare & Medicaid Services)
3. Run a NAIC/state DOI complaint search for that carrier and plan contract — look for repeated complaint themes (claims, preauth, coverage). (Government of India)
4. Look up denial metrics (KFF, Health Affairs, AHA analyses) for the carrier — check prior authorization and initial-claim denial rates. (KFF)
5. Read NCQA HEDIS/CAHPS detail — are there glaring gaps (e.g., poor chronic care control)? (NCQA)
6. Check region-specific J.D. Power or CAHPS — satisfaction differences by region are common. (J.D. Power)
7. Ask two local providers whether they find the insurer easy to work with — are claims paid timely, prior auth realistic, appeals manageable?
8. Decide: pick the insurer that balances quality metrics and access — often the “best” local network with decent complaint/denial numbers beats a national 5-star plan that doesn’t cover your doctors.

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Common consumer myths — busted

• Myth: A top star rating means no problems.
  Reality: high stars are good signals but don’t guarantee low denials or excellent customer service in every local plan. Always check operational metrics too. (Centers for Medicare & Medicaid Services)
• Myth: Complaints are just noisy and meaningless.
  Reality: a pattern of similar complaints (claims, denials, billing) across states and years is one of the best predictors of future headaches. Regulators use these patterns to open investigations. (Government of India)
• Myth: If a plan is the cheapest, it’s a bargain.
  Reality: low premiums can reflect narrow networks, weak coverage of specialty drugs, tougher prior authorization, and higher denial friction — which can cost you time, stress and money later. (American Hospital Association)

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What the regulators and researchers are saying (short synthesis)

• CMS continues to refine star methods and uses them for bonuses and beneficiary tools — but methodology shifts mean year-to-year comparisons require context. (Centers for Medicare & Medicaid Services)
• NAIC / state DOI: complaint indices are public and powerful; use them to spot patterns of consumer grievances. (Government of India)
• KFF and Health Affairs: researchers show big differences in prior authorization and denial rates across carriers — a practical daily measure of plan behavior. (KFF)
• Industry analysts & surveys (J.D. Power): member satisfaction often diverges from clinical measures, underscoring the need to consider both. (J.D. Power)

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What to do if you’re already stuck with a “bad” plan

1. Document everything: save denial letters, explanation of benefits (EOBs), preauthorization numbers, and dates of service.
2. File internal appeals right away (follow your plan’s timetable and keep copies). Many denials are overturned on appeal. (Health Affairs)
3. File complaints to your state DOI and the NAIC complaint portal — regulators track patterns and can pressure insurers. (Government of India)
4. Ask for an external review if your state or ERISA plan permits it — independent reviewers sometimes reverse denials.
5. Talk to your provider — often hospitals/physicians can help with appeals or peer-to-peer reviews. Providers overturn a surprising share of denials. (American Hospital Association)
6. If you’re on Medicare Advantage, check for special enrollment or switching windows — sometimes poor star ratings can trigger plan changes or special enrollments. (Centers for Medicare & Medicaid Services)

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A final word: how to think like a regulator (and outsmart the worst insurers)

Regulators look for patterns over time: repeated complaints, persistent denial rates, and poor quality scores across multiple measures. You can do the same — don’t be dazzled by one shiny number. Think in layers:

• Clinical quality (NCQA/HEDIS) → Are preventive and chronic-disease measures good?
• Member experience (CAHPS, J.D. Power) → Are people satisfied?
• Operational friction (complaints, denial rates) → Will the plan make care hard to access?
• Local network & providers → Will your doctors accept the plan and get paid quickly?

If a plan fails on operational friction (denials, appeals, complaints), it will feel bad to use, no matter how many clinical checkboxes it ticks. Focus on both quality and usability.

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Useful resources & where to look first

• CMS Star Ratings & technical notes (Medicare Advantage & Part D). (Centers for Medicare & Medicaid Services)
• NCQA Health Plan Ratings and report cards. (NCQA)
• NAIC complaint index and state DOI complaint reports (search your state DOI for breakdowns). (Government of India)
• KFF analyses on prior authorization, denial rates and marketplace research. (KFF)
• J.D. Power U.S. Commercial Member Health Plan Study for member satisfaction. (J.D. Power)

(I linked to the CMS star-ratings fact sheet and a sample NAIC complaint-index PDF earlier — use those two anchors as your quick starting points.) (Centers for Medicare & Medicaid Services)

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Short checklist you can copy/paste when shopping (one-page summary)

• Is the plan type covered by CMS or NCQA reports? (If Medicare → CMS; commercial/Medicaid → NCQA.) (Centers for Medicare & Medicaid Services)
• Does the plan have a complaint index or DOI complaint history that’s elevated? (Search NAIC & state DOI.) (Government of India)
• Prior authorization denial rate: is it > ~10%? If yes, dig deeper. (KFF)
• Initial claims denial rate: is it well above ~12%? If yes, consider alternatives. (Health Affairs)
• Do local providers accept and like the plan? (Call two offices.)
• Does the plan cover your regular medications without burdensome PAs?
• Are preventive and chronic-care measures reasonable on NCQA/HEDIS? (NCQA)

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Closing: star badges are helpful — but the hidden numbers keep you safe

Stars are shorthand. They’re useful, but they are not the complete story. The hidden numbers — complaints, denials, prior-authorization friction and member satisfaction — often tell you which insurers will make your life harder when you’re sick or need a claim paid.

If you only take one thing from this post: triangulate. Look at the public star scores, then check operational metrics (complaints, denials, appeals) and local provider feedback. That’s how you find the insurers that look good on paper but are actually the worst to use — and how you avoid them.

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References (sources used for facts and figures in this post)

• CMS — 2025 Medicare Advantage & Part D Star Ratings fact sheet and technical notes. (Centers for Medicare & Medicaid Services)
• NAIC / state DOI complaint index sample reports (example PDF). (Government of India)
• NCQA — Health Plan Ratings and 2024 release notes. (NCQA)
• J.D. Power — U.S. Commercial Member Health Plan Study (2024/2025 releases). (J.D. Power)
• KFF (Kaiser Family Foundation) analysis of prior authorization and denial rates for Medicare Advantage and marketplace plans. (KFF)
• Health Affairs and other peer-reviewed studies on claims denial rates. (Health Affairs)
• Becker’s Payer/Healthcare industry reporting on lowest-rated plans in NCQA 2024. (Becker’s Payer Issues | Payer News)
• Reuters reporting on insurer disputes and industry reaction to star ratings. (Reuters)